fire safety design in buildings - canadian wood council · title: fire safety design in buildings...

Fire SafetyDesign inBuildings

A reference for applying the

National Building Code of

Canada fire safety requirements

in building design

Fire SafetyDesign inBuildings




in building design

Canadian ConseilWood canadienCouncil du bois

Fire Safety Design inBuildings




in building design

Canadian ConseilWood canadienCouncil du bois

1996 CopyrightCanadian Wood Council Conseil canadien du boisOttawa, Ontario Canada

ISBN 0-921628-43-9

Printed in Canada

2.5M796, 2.5M91

Photograph Credits

Beinhaker/Irwin Associates 226Byrne Architects 2Graham F. Crockart Architect 133CWC 5, 31, 43, 57, 78, 80, 130, 201, 215, 217, 229, 305, 313, 314, 320, 323, 326Dalla-Lana/Griffin Architects 192Ivan G. Dickinson, Architect 73Fire in America 3, 9, 11Harold Funk Architect 294Gauthier, Guité, Daoust, Lestage Architectes 28, 32Griffiths, Rankin, Cook Architects 270Hemingway, Nelson Architects 266Henriquez Partners 70The Hulbert Group 50, 198IBI Group Architects 283NRCC 15Ottawa Citizen 63, 302Allan Rae Architect 144, 181F.J. Reinders & Associates 221Tolchinsky and Goodz Architect 61Lubor Trubka Architect 193

The Canadian Wood Council(CWC) is the national federationof forest product associations.CWC is responsible for the development and distribution oftechnical information includingcodes and standards, and fire safety design for buildings.

Fire Safety Design in Buildingsis one of the CWC publications*developed to assist designers. It isintended to help designers applythe fire safety requirements of the National Building Code ofCanada for all buildings. This is a companion, explanatory document to the NBCC.

Fire Safety Design in Buildingscompliments the Wood DesignManual, Wood ReferenceHandbook and other CWC publications. Together they pro-vide a comprehensive family ofreference material for profession-als involved with building design.

The Canadian wood industrydevotes considerable resources for fire research programs toimprove the understanding of theperformance of wood products infire. This fire research will beused to support a Canadianapproach to a world-wide trendtoward building codes based on performance instead of prescriptive requirements.

The Board of Directors, members,and staff of the Canadian WoodCouncil trust this book will assistyou in designing with wood - therenewable resource.

Kelly McCloskeyPresident

*For more information on CWC design tools callthis toll free number: 1-800-463-5091

Foreword i

Foreword

ii Fire Safety Design In Buildings

In a recent survey of buildingspecifiers, the majority perceivedwood to be the most environmen-tally friendly building material.Compared to other major buildingmaterials, this is due mainly to:

• the renewability of wood• the low energy consumption

required for production• the low levels of pollutant

emission during manufacture

Lately, environmental con-siderations have acquired moreimportance in the specificationof materials. Technical and

economic aspects of buildingmaterials have always been primary considerations for specifiers. Increasingly, however,they are considering the environ-mental effects when selectingappropriate building materialsfor their designs.

Architects, engineers and design-ers require accurate informationto assess the true environmentalconsequences of the materialsthey specify.

The environmental impacts ofvarious building materials havebeen examined by a CanadianResearch Alliance using theinternationally accepted methodcalled Life-Cycle Analysis (LCA).The Alliance consists ofresearchers from the wood, steel and concrete industries as well as university groups and consultants.

Life-cycle analysis evaluates thedirect and indirect environmentaleffects associated with a product,

process or activity. It quantifiesenergy and material usage andenvironmental releases at eachstage of a product’s life cycleincluding:

• resource extraction• manufacturing• construction• service• post-use disposal

One product of this three yearlife-cycle project is a computermodel, AthenaTM , that facilitatescomparative evaluation of the environmental effect of building assemblies.

In addition to those familiar qualities that have made woodsuch a dominant material inNorth America, the Life-CycleAnalysis methodology confirmswood products to be a wise choicefor designers from an environ-mental standpoint.

The reasons for this are explainedin the following information:

RESOURCE EXTRACTION:

The environmental effects ofresource extraction are the mostdifficult to quantify because ofthe variability of extractionmethods and the variability inthe ecology of different sites.

The study made the followingobservations:

• There are three dimensions tothe extraction process: exten-siveness, intensiveness, andduration.

The Environmental Benefits of Building with Wood iii

The Environmental Benefits of Building with Wood

• All extraction creates signifi-cant ecological impacts.

• Mining extractions are moreintensive and endure longerthan forest extractions.

• Forest extractions are moreextensive in terms of land areaaffected.

Of all the phases of the life-cycle,extraction is the most subjective.The ecological impacts of forestcutting can differ by severalorders of magnitude from bestpractice to worst practice.

Similarly, the differences betweenthe worst practices and the best practices of each extractiveindustry may well be greater than the differences betweenthose industries. This does notoffer a definitive conclusion, buthighlights the importance ofCanada’s leadership in practisingsustainable forestry.

MANUFACTURING:

During the manufacturing stage, raw resources are convert-ed into usable products. The manufacturing stage is the mosteasily quantifiable stage as allthe processes are under humancontrol, and the stage where theenvironmental advantage ofusing wood is most apparent.

Wood requires much less energy to manufacture and causes muchless air and water pollution thansteel or concrete.

The AthenaTM model was used to compare the environmental

effects of a non-loadbearing steel-stud wall to a wood-stud wall.Compared to the wood-stud wall,the steel-stud wall:

• used three times more energy• produced three times more CO2

• used twenty five times morewater

• had a much greater impact onthe quality of the water and air

The wood wall, by requiring muchless energy to manufacturereduces the use of fossil fuels.Fossil fuels are non-renewableand their use is linked to globalwarming, thinning of the ozonelayer and acid rain.

CONSTRUCTION:

The construction stage includeson-site construction as well astransportation of the materialsfrom local plants or suppliers.

The major impacts at the con-struction stage are caused by theenergy used for transportationand construction equipment andthe solid waste generated duringconstruction. Comparison ofbuilding materials in this life-cycle phase showed no major differences in energy use.

However, the study did determinethe wood-framed wall generatedone third more waste on the jobsite than the steel-framed wall. The quantity of solid wastegenerated from wood framingdepends greatly on the construc-tion system used and builder’sattention to material use.

iv Fire Safety Design In Buildings

Changing economics are reducingconstruction waste from woodframe construction and redirect-ing it to other uses than landfill.

SERVICE:

The service phase of the life-cycleis the period when the materialperforms its function as part ofthe structure.

Framing materials do not presentenvironmental impacts when theyare in service since they consumeneither energy nor resources.However, the choice of buildingmaterials can significantly affect the energy requirements for heating and cooling.

When compared with steel, wood isa much better thermal insulator.Thus, wood-frame structures con-sume far less energy for heatingand cooling than steel-frame structures for the same quantity ofinsulation. For more informationon the insulating properties ofwood and steel frame construction,please consult the Canadian WoodCouncil publication, The ThermalPerformance of Light-FrameAssemblies.

POST-USE DISPOSAL:

The last stage of the life-cycle,post-use disposal, is difficult toassess because it takes place far inthe future – at the end of the use-ful life of the product.

Steel is better established as arecyclable material with facili-ties in place. The wood recycling

industry in Canada is still in itsinfancy but is expanding rapidly.Several large centres in Canadahave wood recycling facilities thatuse wood scrap to produce horti-cultural mulch or wood chips forhardboard.

Recycling is a return to the man-ufacturing stage, and as woodrecycling increases, the environ-mental advantage of wood duringthis stage will be apparent.Where wood recycling facilitiesare not available, wood productsare biodegradable and return tothe earth and ultimately arerenewed through new growth.

CONCLUSION:

In spite of scientific analysesthat demonstrate many environ-mental advantages for woodbuilding materials, the publicstill has concerns about wood.This is due in part to the highlyvisible effects of wood resourceextraction.

To address these concerns, theCanadian Forest Industry, inaddition to adopting enhancedforest management techniques, is actively supporting the devel-opment of Sustainable ForestryCertification Standards by theCanadian Standards Association(CSA). Certification assures consumers that the products theybuy are made from wood thatcomes from an environmentallysound and sustainable forestryoperation.

The Environmental Benefits of Building with Wood v

The preceding information formsthe basis for responsible choicesby specifiers - choices which arenot always easy or straightfor-ward. Some products are simplybetter suited for particular applications.

Specifying a product that comesfrom a renewable resource, that is energy conservative in

manufacture and use, and thatcan be easily recycled or reused,minimises the environmentalimpact and makes sustainabledevelopment an achievable goal.

Wood is an extraordinary material that offers these environmental advantages.

vi Fire Safety Design In Buildings

Table of Contents vii

Table of Contents

11.1 The National Building Code

of Canada 31.2 Fires that Shaped the Code 91.3 Development of the NBCC 171.4 CCBFC Strategic Plan

and Objective Based Codes 23Chapter Summary 26

2.1 General Information 292.2 Structural Systems in Wood 312.3 Wood in Noncombustible Buildings 39

Chapter Summary 48

3.1 General Information 513.2 The NFPA Fire Safety

Concepts Tree 533.3 Limiting Fire Growth 553.4 Containing the Fire 613.5 Suppress the Fire 653.6 Managing the Exposed 67

Chapter Summary 68

4.1 General Information 714.2 Classification of Buildings 734.3 Determining Construction

Requirements 834.4 Sprinkler Protection 914.5 Storeys Below Ground 95

Chapter Summary 96Design Requirements Tables 97-127

5.1 General Information 1315.2 Fire Separations 1335.3 Fire-Resistance Ratings 1475.4 Alternative Methods for Determining

Fire-Resistance Ratings 1575.5 Fire-Resistance Rating

Requirements in the NBCC 1755.6 Fire Protection Requirements for

Mezzanines and Atriums 1855.7 Fire Stops 1895.8 Sprinkler Alternatives 193

Chapter Summary 195

Building Regulations in Canada

Building with Wood

The NBCC:Assumptions andObjectives

ConstructionRequirements

Structural FireProtection

2

3

4

5

viii Fire Safety Design In Buildings

66.1 General Information 1996.2 Determining Flammability 2016.3 Interior Finishes 2076.4 Fire-Retardant Treated Wood 2136.5 Roof Assemblies 217

Chapter Summary 223

7.1 General Information 2277.2 Objectives and Assumptions 2297.3 Limiting Distance 2337.4 Exceptions to Spatial Requirements 2437.5 Exposure Protection Within

a Building 2457.6 Examples of Spatial Separation

Calculations 251Chapter Summary 264

8.1 General Information 2678.2 Occupant Load 2698.3 Fire Alarm and Detection Systems 2738.4 Means of Egress 2818.5 Safety within Floor Areas of

Specific Occupancies 2938.6 Service Spaces 297

Chapter Summary 299

9.1 General Information 3039.2 Access to Buildings 3059.3 Fire Protection Systems 311

Chapter Summary 317

10.1 General Information 32110.3 Fire Safety in High Buildings 323

Chapter Summary 328

Information Sources 331Index of Tables and Figures 337Bibliography 341Index 345Index of Code References 355

7

8

9

10

Flame Spread ofMaterials

Fire Spread BetweenBuildings

Fire Safety within Floor Areas

Provisions forFirefighting

High Buildings

Appendix

Every effort has been made to ensure the data and information in this document is accurate and complete. The Canadian Wood Council does not, however,assume any responsibility for error or omissions in the document nor for engineering designs or plans prepared from it.

1BuildingRegulations in Canada1.1 The National Building Code of Canada . . . . . . . . . . . . . . . . . . . 3

The Origin of Building Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

The Modern NBCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Division of Building Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

National Fire Protection Association . . . . . . . . . . . . . . . . . . . . . . . 6

The NBCC and This Document . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.2 Fires that Shaped the Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Cocoanut Grove Nightclub . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Laurier Palace Theatre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Catastrophic Hotel Fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

High Rise Fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.3 Development of the NBCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Standing Committees of the CCBFC . . . . . . . . . . . . . . . . . . . . . . 18

Canadian Codes Centre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Code Change Cycles and Public Input . . . . . . . . . . . . . . . . . . . . 19

Relationship between the NBCC

and the NFCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.4 CCBFC Strategic Plan and Objective Based Codes . . . . . . . . .23

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

The National Building Code ofCanada (NBCC) is widely acclaimed,not only in Canada, but also in othercountries. This is because it is a consensus-based structure for pro-ducing a model set of requirementswhich provide for the health andsafety of the public in buildings.

By historical standards, theNBCC is fairly young but, like itsmany counterparts around theindustrialized world, it draws onthe experience of several centuriesof tragic incidents and attemptsby legislators to provide safe-guards against the ever-presentthreat of fire.

THE ORIGIN OF BUILDING CODES

Building construction regulationsare not a new phenomenon. Theearliest recorded legislation governing building constructionis attributed to Hammurabi, Kingof Babylon, around 1700 BC.

His decree placed the responsibilityfor the structural sufficiency of a

building on the builder, based onthe principle of “an eye for an eye.”A builder would be executed if thehouse he built collapsed andcaused the death of the owner. Inaddition, early Roman laws showthat legislators sought to prohibitconstruction of dense clusters ofmulti-storey wood structures thatmade it impossible to confine theeffects of fire to a single property.

Throughout history, fire has beenthe most common form of disasterto human settlements. Thoughincendiary acts during wartimeprobably accounted for the great-est devastation, sources of fire forcooking, lighting and heatingconstituted a constant hazard. Intimes past, these have destroyedentire villages and towns.

Hence, early building ordinanceswere almost always developed to control sources of fire, and frequently included fines as adeterrent against carelessness.But the gravest threat remainedarson. Throughout the 17th, 18th

Canadian building regulations provide forextensive woodstructures

The National Building Code of Canada 3

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1.1 The National Building Code of Canada

FIGURE 1.1

The BostonFire in 1872was one ofseveral majorcity fires thatidentified theneed for newfire regulations

and 19th centuries, arson was ascourge that defied every ounceof vigilance. Eventually, itbecame clear that the construc-tion and location of buildingsneeded to be addressed.

Conflagrations such as the GreatFire of London in 1666, whichdestroyed some 13,000 properties,led to the introduction of theLondon Building Act. This is con-sidered the first comprehensivebuilding code.

This law, written under the guidance of Sir ChristopherWren, defined four classes ofbuildings and specified how andwhere they were to be built.Critical aspects included:

• prohibition of thatched roofsand timber chimneys

• specific requirements for wallconstruction

• limits on building heights

The Great Fire of London alsoheralded the establishment of fire insurance companies whichwould often become catalysts inthe production of standards forfire safety in buildings.

In the United States, buildingconstruction regulations dateback to the 17th century. InBoston, laws were passed thatprohibited thatched roofs andwooden chimneys and requiredstone or brick walls on buildingsafter two fires destroyed majorparts of the city in 1631 and 1679.

Throughout the 17th and 18th centuries, many other communitiesenacted similar ordinances in the aftermath of major fires.

Although these laws containedspecifications on building con-struction, most requirements still concerned ways to limit the spreadof fire and the availability of firefighting means. These types ofrequirements form today’s fire pre-vention codes such as the NationalFire Code of Canada (NFCC), discussed later in this chapter.

The promulgation of modernbuilding codes essentially beganin the US and Canada at the turnof the century after some majorconflagrations.

Quebec City (1866), Chicago(1871), Boston (1872), Saint John (1877), Ottawa-Hull (1900),Baltimore (1904), Toronto (1904)and San Francisco (1906) all suffered disastrous fires whichleft many thousands homeless.These fires served as lessonswhich led to the introduction of regulations governing:• distances between buildings• limitations on building height• the use of combustible materials

such as cladding on buildings

There were also tragic incidentsinvolving single buildings such asthe Iroquois Theatre fire inChicago in 1903, where 602 died,and a number of other fires in hospitals and schools that resultedin extensive loss of life.

In Canada and the US, municipalby-laws spread across the country.Even though the regulation ofbuilding construction is a provincialresponsibility under the constitu-tion of Canada, provinces usuallydelegated this authority to munici-palities prior to the 1970s.

4 Fire Safety Design In Buildings

In the 1930s, there were probablyas many different building codesin Canada as there were munici-palities with sufficient construc-tion activity to warrant some formof regulation. All of these variedgreatly in technical content andsophistication.

Because of the lack of engineeringdata upon which fire protectioncould be based, some codes required excessive fire protectionat great cost while others did notadequately address the fire risk.This created a very confusing situation for designers, buildersand manufacturers.

In 1918, J. Grove Smith fullyexplored the Canadian situation in a report of the Commission of Conservation, Fire Waste inCanada. He advocated the develop-ment of uniform standards forbuilding construction and fire control. The report emphasized tothe regulating authorities theneed for better controls in build-ing construction and contributed

to Smith’s appointment as the firstDominion Fire Commissioner. Italso influenced those responsiblefor the creation of Canada’s firstmodel building code.

THE MODERN NBCC

The National Housing Act (NHA)was originally created to promotethe construction of new houses, therepair and modernization of exist-ing homes and the improvement ofhousing and living conditions.

When it was introduced in the1930s, it was recognized that itsimplementation would be greatlyfacilitated by the adoption of uniform house construction stan-dards throughout the country. Italso became apparent that othertypes of building constructionwould benefit from a uniform setof construction requirements.

As a result, the Department ofFinance, then responsible forapplication of the NHA, enlisted

FIGURE 1.2

NationalBuilding Codeof Canada,1941, 1953,1995


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the help of the National ResearchCouncil of Canada (NRC) to developa set of model regulations whichcould be adopted by any enablingjurisdiction in Canada. Jointly,they produced the first edition ofthe NBCC, released in 1941.

DIVISION OF BUILDING RESEARCH

Subsequent to this first effort, itwas acknowledged that a buildingcode must be updated to respond to economic and technologicalchanges in the field of construc-tion. Furthermore, as buildingswere growing in size and heightthrough advances in structuraldesign, new materials and heatingand ventilating equipment, a num-ber of questions arose regarding:• the spread of fire within and

between buildings• structural sufficiency under

fire exposure• structural sufficiency under

severe loads such as earthquakes• human behaviour during

emergencies

These considerations and a call byprovincial fire enforcementauthorities for more research per-tinent to the Canadian context ledthe NRC to create, in 1947, theDivision of Building Research(DBR). This was a research andtechnology information service forthe Canadian industry which isnow known as the Institute forResearch in Construction (IRC).

The DBR was also responsible forproviding technical and secretarialsupport to the Associate Committeeon the National Building Code

(ACNBC), established in 1948 tooversee the development of theNBCC. In 1991, the ACNBC and the Associate Committee of theNational Fire Code were replacedby a single committee, theCanadian Commission on Buildingand Fire Codes (CCBFC).

The CCBFC is one of many com-mittees the NRC uses to bringtogether specialists from acrossthe country to guide its activitiesso that it may better respond tonational concerns.

By the 1970s, responsibility forthe application of building regu-lations had shifted from local toprovincial governments. TheProvincial Advisory Committee,composed of representatives fromthe provincial building standardsdepartments, was formed toensure that provincial concernswere taken into account in thedevelopment of the NationalBuilding Code of Canada.

In 1990, this committee wasreplaced by the Provincial/Territorial Committee onBuilding Standards (PTCBS)which brought together higherlevel representatives to ensure aneven greater provincial commit-ment to the national model code.

NATIONAL FIRE PROTECTION ASSOCIATION

The first edition of the NBCC was,for the most part uniquelyCanadian, with account taken ofUS experiences. The subsequentelaboration of the NBCC was morestrongly influenced by fires in the


US, particularly through the par-ticipation of Canadian fire officialsin the work of the National FireProtection Association (NFPA).

This organization, based in theUnited States, plays an importantrole in the development of codesand standards through the investi-gation, analysis and reporting offindings from fires, as well as thepublishing of standards.

Canada’s participation in NFPAdates back to 1912 when a CanadianCommittee of the association wasformed. A recent joint investigationby NFPA and NRC into the fire atthe Forest Laneway Apartments inNorth York , Ontario demonstratesthat co-operation between US andCanadian fire authorities is stillstrong. (Figure 1.6)


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THE NBCC AND THIS DOCUMENT

The National Building Code of Canada contains 9 Parts. Only twoparts relate to fire safety in buildings: Parts 3 and 9.

Part 3 applies to:• all places of assembly• all care and detention facilities such as hospitals, nursing homes

and detention centers• all high hazard industrial buildings• all other types of buildings over three storeys or 600m2 in area

Part 9 applies to buildings of three storeys or less up to 600m2 inarea, except for assembly, care and detention or high hazardindustrial buildings.

This document deals essentially with Part 3 of the NBCC thoughreferences are made to Part 9 from time to time.

The basic fire safety objectives of the NBCC are explained as wellas the rationale for:• compartmentation • fire-resistance ratings• flame-spread ratings • spatial separation• means of detection and alarm • fire suppression systems• means of egress • provisions for firefighting

Code references are indicated throughout as ]3.2.2.26]. OfficialCode Definitions of terms are indicated by underlining the termand the definition is in quotation marks.

Special emphasis is given to the use of wood and wood productsin buildings of all types, including those required to be of non-combustible construction.

After 1904, the year of the BayStreet fire in Toronto, improve-ments in building construction andfirefighting equipment appeared tostem the rash of fires which haddestroyed downtown districts.

The building codes in effect atthe beginning of the centuryreflected an understanding of the need for fire-resistive con-struction and the protection ofopenings.

FIGURE 1.3

Fire claimed492 lives atBoston’sCocoanutGrove in thefall of 1942. Ithad a signifi-cant impact on regulationsfor exits andinterior finishes

Fires that Shaped the Code 9

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1.2 Fires that Shaped the Code

Further refinements in buildingcodes evolved from single propertytragedies. Contributing factorstypically included:• inadequate building construction• lack of egress facilities• poor or non-existent alarm

systems

COCOANUT GROVE NIGHTCLUB

The notorious fire at Boston’sCocoanut Grove in 1942 had asignificant impact on public consciousness.

At the time of the fire, theCocoanut Grove nightclub wascrowded far beyond capacity. Theofficial seating capacity of thelounges and bars was about 600,but about 1,000 people occupied theone-storey building. In the base-ment, the Melody Lounge was alsoover full.

The walls and low ceiling of thelower lounge were covered with acotton fabric and decorated withflammable artificial coconutpalms. At about 10 p.m., some-thing ignited as a bus-boy wasreplacing a light bulb near one ofthe artificial trees. Fire sweptover the heads of the patrons withincredible speed as it caught thedecorations. Within seconds,flames filled the only visiblemeans of exit, a stairway at therear of the lounge.

Flames soon reached the groundfloor, swept across the ceiling andenveloped each room with suchspeed that people had no time toreact. Most tried to escapethrough a revolving door whichsoon jammed under the pressure.

Several other doors throughwhich people could have escapedwere locked or hidden from view.As smoke filled the building, peo-ple were overcome by the noxiousfumes; some died sitting at theirtables. By the time it was over, 492 people had lost their lives.

The contributing factors in thistragic incident in a meeting placeare obvious:• it was overcrowded• decorations were highly

combustible• exits were few, poorly lit,

unmarked, locked or blocked• exits did not open in the

direction of exit travel

These same contributing factorsplayed as significant a role in asimilar tragedy which occurred in 1977 in Kentucky. The BeverlyHills Supper Club fire was theworst multiple-death buildingfire in the United States since theCocoanut Grove fire, resulting inthe loss of 164 people.

LAURIER PALACE THEATRE

Another fire incident, whichoccurred in Montreal on January9, 1927, claimed fewer casualtiesthan the Cocoanut Grove fire.However, with one exception, allwere children under the age of 16.

At the time of the fire, the LaurierPalace Theatre was filled to capac-ity. The fire station was directlyacross the street. When the alarmsounded, firefighters went intoaction immediately. On enteringthe building, they discovered, totheir horror, that bodies were piled


in a solid mass in one of the nar-row stairways leading from the balcony.

The stairs were steep, enclosed by walls and narrowed at the bottom. One of the children hadobviously stumbled and causedthe others, rushing toward theexit, to trip and fall. Smoke keptdriving people down the stairs

and the pile grew bigger andbecame more solidly wedged inthe passageway.

In the end, 78 children had died,52 died of asphyxiation, 25 werecrushed to death and 1 burned. Forthe next 40 years or so, childrenwere prohibited from motion pic-ture theatres in the province ofQuebec.

FIGURE 1.4

A fire on theground floor of Chicago’s22-storeyLaSalle Hotel,considered tobe a “fire-resistive”building, senthot gasesthrough theventilation system to the upperfloors, forcingevacuation.


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CATASTROPHIC HOTEL FIRES

In 1946, three major hotels in theUS suffered severe fires whichcost many lives:• the Lasalle Hotel in Chicago• the Canfield Hotel in Dubuque• the Winecoff Hotel in Atlanta

These fires increased awareness ofthe safety problems inherent tothese occupancies in tall build-ings, and the unpredictablebehaviour of people in cases ofdire emergency.

The LaSalle was considered a fire-resistive hotel. The 22-storeybuilding was constructed of pro-tected-steel frame and reinforcedconcrete, with brick exteriorwalls and 3-inch plastered hollowtile partitions. It even featuredthree enclosed noncombustiblestairways, though they did notopen directly to the outside atground level.

Unfortunately, the building’sweaknesses came to light in June,1946, when a fire broke out in thecocktail lounge on the groundfloor. The exhaust ventilationfrom the lounge discharged intothe elevator shaft, sending hotgases directly to the upper floors.The lobby and mezzanine weredecorated with walnut veneerpanelling and were connected toan open stairway to the upperfloors. In addition, the bedroomdoors had transom windows, andmany were open at the time of the fire.

One of the disturbing aspects ofthis fire was the way in whichpeople reacted. Many fell to theirdeath by jumping from windowsor trying to escape by climbingdown bed sheets tied together.Similar behaviour was seen inlater fires including one at theTaeyonkak Hotel in Seoul, SouthKorea, in 1971.

FIGURE 1.5

A welder’storch ignitedcombustibleinsulationmaterial in thebasement ofthe highriseCIL House,Montreal in1962


1 1 1 2

3

6

BankLobby

Shops5

4

Ramps

7 8Parking

ParkingParking

Parking

Storage

Restaurants

North South

Partial Elevation(Schematic only), Fire area darkened

1. Elevators2. East Service shaft3. Trust Co. elevator4. Machinery room, origin of fire5. Escalator6. Stairway7. Service elevator8. Service stairway

Smoke from fire that fed on combustible insulation on pipes and ducts in a service shaft forced 3,000 people in this 36-storey building to leave. The fire was confined to the shaft and did not get above the fourth-storey level.

Source: NFPA Quarterly — October 1963

Similarly, at the Canfield andWinecoff hotels, a lack of com-partmentation hastened thespread of smoke, heat and flamesup open staircases and throughopen transom windows into guestrooms. Another significant factorwas a delay in alerting occupantsto the fire.

At the Winecoff Hotel, where 122people lost their lives, there wasno automatic alarm system inthe building. It is estimated thatthe fire burned for at least halfan hour before the fire depart-ment was notified.

More recent fire losses in hoteloccupancies include:• MGM Grand Hotel in Las

Vegas in 1980 (84 deaths)• Dupont Plaza Hotel in San Juan,

Puerto Rico in 1986 (96 deaths)

Both fires originated in and aroundthe casinos on the lower floors ofthe building. Lack of sprinklersand unprotected floor openingswere cited as major factors in thespread of smoke and fire into highrise portions of the building.

HIGHRISE FIRES

In the latter part of the 1960s andthe early 1970s, attention focusedon the fire safety of highrisebuildings.

Though usually of fire-resistiveconstruction, these buildings had anumber of design deficiencies.These centred around the verticalshafts required for building ser-vices, such as elevators, stairs,pipes, ducts and electrical cables.

These shafts are subject to what iscalled the “stack effect.” In coldweather, the heating of a buildingdraws air into the building at lowlevels and out at upper levels. Thenatural movement of warmer airfrom bottom to top is caused bypressure differentials from tem-perature differences at the exteriorboundaries of the building.

In addition, taller buildings housea larger number of people whohave a longer route to evacuation.Studies by NRC and the USNational Bureau of Standards(now National Institute ofStandards and Technology) showthat evacuation of tall buildingscan take up to two hours.

The fire at the CIL House inMontreal in December, 1962, typified the potential for disasterin highrise structures.

At about 10 a.m., welders workingon ducts in a service area on thesecond basement level acciden-tally set fire to combustible pipesor duct coverings. The small firequickly spread upward because ofthe natural draft in the serviceshaft, and smoke began spreadingthroughout the structure as thefire consumed the combustibleinsulation and coverings withinthe shaft.

The alarm system which soundedthroughout the entire building atone time, proved inadequate.Evacuation was delayed as floormanagers far removed from thestart of the fire, and unaware ofthe reason for the alarm tried toassess the situation.


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Eventually, employees were toldto evacuate. The almost simulta-neous evacuation of all floorsresulted in crowded, smoke-filleddarkened stairwells with noemergency lighting. Fortunately,there were no casualties.

Other fires in highrise buildingsattracted attention and had moretragic outcomes.

The fire at Dale’s PenthouseRestaurant in Montgomery,Alabama, killed 25 peopleAlthough the structure was only10 storeys, the occupants of therestaurant on top of the buildingwere beyond the reach of firedepartment ladders.

Another fire in the Rault Center inNew Orleans, Louisiana, resulted insix deaths. Five women in a beautysalon on the 15th floor becametrapped, while a man died of smokeinhalation in an elevator. Againthe fire began on a floor that couldnot be reached by aerial ladders.

A recent fire at the ForestLaneway high-rise apartments inNorth York, Ontario resulted insix deaths. Stack effect is believedto have contributed to the loss.The fire originated and wasmainly contained to the fifthfloor yet all the casualties werelocated above the 20th floor.(Figure 1.6)

Tall buildings remain controver-sial today. The question, “Whowould dream of constructing abuilding over 500 feet long, hous-ing several thousand people, butwith exits only at one end?” isstill heard.

Intensive pioneering research atIRC has resulted in elaboraterequirements for smoke ventingwhich are referenced in theNBCC. Though it is acknowledgedthat these measures for smokecontrol are sometimes difficult toachieve, the research has con-tributed to the understanding ofproblems of smoke movement intall buildings.

LESSONS LEARNED

From the 1950s to the early 1970s,a number of tragic fires in hospi-tals, schools and nursing homesheightened public awareness ofthe potential for disaster in suchbuildings. Hospitals were (andare) particularly vulnerablebecause of the difficulty of moving patients. Furthermore,many of the buildings were of anolder design, with open stairways,corridors and vertical shafts, nosprinklers, and no automatic firedetection and alarm systems.

The lessons learned from these andother past fires had a direct impacton the shaping of building codes.Both in Canada and the US, exist-ing regulations were revised andaugmented to prevent recurrenceof such tragedies. Over the yearsthese revisions have included suchthings as:

• noncombustible constructionbeing stipulated for somebuildings

• limits being placed on the flam-mability of building materials

• introduction of compartmenta-tion concepts


• requirement for fire alarmsand means of fire detection

• improvements in means ofegress

Many older buildings violatedmany of the fire safety principleswhich now form the basis of theNBCC. These principles are dis-cussed in detail in Chapter 3.

FIGURE 1.6

Recent firescontinue toemphasize thefire hazards of high-risestructures


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Once a closed process, the develop-ment of the NBCC and its associateddocuments has become much moreopen in recent years, allowing forinput from all segments of thebuilding community.

In preparation of the 1995 Code,the former Associate Committeeof the National Building Codewas merged in 1991 with theAssociate Committee of theNational Fire Code to form the Canadian Commission onBuilding and Fire Codes (CCBFC).

This Commission is composed of30 to 35 leading Canadian citi-zens in the field of construction.It gives policy guidance to anumber of Standing Committeeswhich are responsible for thetechnical aspects of one or moreparts of the NBCC. TheCommission, in turn, receivesguidelines on matters relating tothe NBCC from provincial andterritorial code authoritiesthrough the Provincial/Territorial Committee onBuilding Standards (PTCBS).

TABLE 1.1

NBCC StandingCommittee onFire Protection

Development of the NBCC 17

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1.3 Development of the NBCC

Interest to be Minimum Number Sources to be Reflected of Members Drawn From

Regulatory

Building Officials 3 Provincial, territorial and municipal regulatory authorities

Fire Officials 2 Provincial and territorial fire marshals’ or fire commissioners’ staffs, municipal fire services (fire chiefs or fire prevention officers)

Federal agencies 1 Federal agenciesenforcing buildingregulationsSub-total 6IndustryBuilding owners or 1 Building owners or developers with technical developers capability and an awareness of costConstruction 1 Construction managers or building managers or contractors with a knowledge of building building contractors materials and construction methodsManufacturers, 4 Major material interestsfabricators or theirassociationsSub-total 6General InterestArchitects 2 At least one from the private sectorEngineers 2 At least one from the private sectorResearch and 2 Testing and inspection agencies includingtesting provincial and municipal laboratories Total 18

Source: Canadian Commission on Building and Fire Codes Policies and Procedures, 1992.

Efforts by the CCBFC and IRChave made the National BuildingCode of Canada (NBCC) the basisfor most provincial and municipalbuilding regulations in Canada.The NBCC has demonstratedclearly the validity of the consen-sus approach through which it isdeveloped and maintained.

The NBCC is not a federal docu-ment produced by the NationalResearch Council of Canada.However, NRC is its publisherand maintains copyrights. TheNBCC is a national model codeand its content is the sole respon-sibility of the CCBFC.

STANDING COMMITTEES OF THE CCBFC

Between 1990 and 1995, there werenine active Standing Committees.The composition of each StandingCommittee follows a matrix established by a NominatingCommittee of the CCBFC.

Each matrix tries to ensure anappropriate mix of expertise bydrawing from every major sectorof the construction industry. TheNominating Committee makesevery effort to obtain as wide ageographical distribution as possible in filling the positions,thus making the NBCC a trulynational document (see Table 1.1).

Members of Standing Committeesare appointed on the strength oftheir knowledge and professionalinterest, and not as direct representatives of a particularindustry, association or interestgroup. This approach keeps dis-cussions as free and uninhibited

as possible. Members give theirtime and expertise without remu-neration; they are reimbursedonly for traveling expensesincurred to attend meetings.

Standing Committees oftenappoint task groups to help withthe task of evaluating informa-tion. These committees of expertsaddress specific questions whichrequire specialized knowledge.The reports of these task groupsoften lead to changes in the Code.

For example, in preparing the pro-posed changes for the 1995 NBCC, aspecial task group was created tostudy all aspects of the use of auto-matic sprinkler systems. As a resultof this task group’s work, signifi-cant changes related to sprinklerswere adopted in the 1995 NBCC.

Over 250 individual members con-tributed to the 1995 NBCC at anestimated personal cost of over $6million. Those who feel they haveknowledge to contribute to thisongoing process should contact theSecretary of the Commission (seeaddress in the list of organizationsat the back of the book).

CANADIAN CODES CENTRE

The effectiveness of CodeCommittees depends, of course,on the contribution of its mem-bers and on good technical andsecretarial support. The primaryfunction of IRC’s CanadianCodes Centre (formerly the CodesSection) is to provide such sup-port. The Centre ensures that theCommittees have the informa-tion to enable them to makeenlightened decisions.


The Centre co-ordinates input fromthe Research Sections of IRC, suchas the Acoustics Laboratory and theNational Fire Laboratory, and fromother sources. Committees also relyon technical staff at the Centre to:• review public inquiries• draft proposed code revisions• draft new requirements in the

code• review public comments on

proposed changes

This ensures that valuable time isnot wasted by the Committees incollective drafting and to ensureuniformity. The final responsi-bility for the technical content of the Code, however, rests withthe Committees.

The Codes Centre provides secretarial support by preparingagendas and minutes and isresponsible for editing, translatingand printing documents.

CODE CHANGE CYCLES AND PUBLIC INPUT

The NBCC and its associated documents, such as the NationalFire Code of Canada and theCanadian Plumbing Code, havebeen published every five years.During any five-year code-revisioncycle, there are many opportunitiesfor the Canadian public to con-tribute to the process.

Correspondence is the primarymechanism through which inputis made to the Committees.Anyone who encounters difficul-ties in applying NBCC require-ments can write to the Secretaryof the CCBFC.

The proponent is required to outline the problem and includeproposed code change language insufficient detail so that it can beproperly evaluated by staff andCommittees. The public proposalsare brought to the attention ofthe relevant Committee, unless it is a straightforward issue thatcan be addressed by staff. The correspondent is subsequentlyinformed of any decisions made by the Committee as a result ofthe inquiry.

Members of the public are alsowelcome to attend meetings, asobservers or participants, subjectto rules of order. An observer cannot be party to discussions buta participant is permitted to make a presentation and answerquestions from the Committee.Participants are invited at theprerogative of the Chairman whowill usually base his or her choiceon the relevance of the subject.

The most inclusive vehicle forcontribution is the Public ReviewProcess. At least twice during thefive-year cycle, proposed changesto the Code are published and thepublic is invited to comment. Thisprocedure is crucial as it allowsinput from all those concernedand broadens the scope of exper-tise of the Committees.

Thousands of comments arereceived and examined by theCommittees during each cycle. Aproposed change may be approvedas written, modified and resub-mitted for public review at alater date, or rejected entirely.Those who submit comments areinformed of Committee decisions.


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RELATIONSHIP BETWEEN THE NBCC AND THE NFCC

The National Building Code ofCanada (NBCC) and the NationalFire Code of Canada (NFCC) aredeveloped as companion documents.The relationship between the twodocuments can be better understoodwhen their respective purposes areconsidered.

The NBCC establishes minimumstandards for the health and safe-ty of the occupants of new build-ings. It also applies to the alter-ation of existing buildings, includ-ing changes in occupancy.

The NBCC is not retroactive: inother words, a building constructedin conformance with a particularedition of the NBCC, in effect atthe time of its construction, is notautomatically required to conformto the next edition of the NBCC.That building would only berequired to conform to the new regulations if it were to undergo achange in occupancy or alterationswhich invoke the application of thenew NBCC in effect.

In 1993, the document, Guidelinesfor the Application of Part 3 of theNational Building Code ofCanada to Existing Buildings, waspublished by NRC. It providesguidelines on the intent of therequirements of the NBCC and howthose requirements might beapplied to existing buildings.

A huge proportion of Canadianbuilding stock was constructedbefore modern building codeswere in effect. Upgrading thesebuildings poses a challenge

because conformance with newCode requirements can be veryexpensive.

To make renovations financiallyfeasible authorities having juris-diction may sometimes considertrade-offs or alternatives whichwill provide an equivalent level ofsafety. This forces the authority toassess the intent and objective ofrequirements, a process whichwill inevitably be reflected in the evaluation of requirements fornew buildings.

The requirements in the NFCC,on the other hand, are intendedto ensure the level of safety ini-tially provided by the NBCC ismaintained. With this objective,it regulates:

• the conduct of activities causingfire hazards

• the maintenance of fire safetyequipment and egress facilities

• limitations on building content, including the storageand handling of hazardousproducts

• the establishment of fire safetyplans

Major revisions to the 1995 editionof the NFCC involved changesrelated to the indoor and outdoorstorage of various commodities andprotection of indoor hazardousprocesses.

The NFCC is intended to beretroactive with respect to firealarm, standpipe and sprinklersystems. In 1990, the NFCC wasrevised to clarify that such systems “shall be provided in


all buildings where required byand in conformance with therequirements of the NationalBuilding Code of Canada.”

This ensures that buildings areadequately protected against theinherent risk at the same level asthe NBCC would require for a newbuilding. It does not concern otherfire protection features such assmoke control measures or fire-fighter’s elevators. The NFCC alsoensures that changes in buildinguse do not increase the riskbeyond the limits of the originalfire protection systems.

The NBCC and the NFCC arewritten to reduce to a minimumthe possibility of conflict in theirrespective contents. They are com-plementary: the NFCC takes overfrom the NBCC once the buildingis in operation. In addition, olderstructures which do not conformto today’s fire safety standardscan be made safer through therequirements of the NFCC.

It is important that building andfire officials be familiar with bothcodes. This will help ensure that allknown hazards have been consideredand that a satisfactory standard offire safety achieved.


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The Canadian Commission onBuilding and Fire Codes (CCBFC) isshifting away from prescriptiverequirements to a greater emphasison an “objective-based” approach tobuilding design in the NBCC.

Prescriptive requirements describeprecisely the types of material andassembly to be used in particularcircumstances. Such requirementsmake alternative design solutionsdifficult because the enforcementofficial has no indication of thereason for the requirement.

On the other hand, performance-based requirements, set forthobjectives which must be met toachieve a given level of safety.This provides the greatest level of

flexibility since authorities canmeasure the solution provided bythe designer against the givenobjectives. The 1995 NBCC stillcontains a large number of pre-scriptive requirements but theemerging trend is toward perfor-mance criteria.

This move to objective-baseddesign will help in the introduc-tion of new materials, systemsand processes. Those responsiblefor their evaluation will be ableto measure these solutions againstclear statements of intent ofNBCC requirements. The evalua-tion process will be further facili-tated through the CanadianConstruction Materials Centre

CCBFC Strategic Plan and Objective Based Codes 23

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1.4 CCBFC Strategic Plan and Objective Based Codes

CCMC

The Canadian Construction Materials Centre (CCMC), at the National Research Council in Ottawa, offers a nationalevaluation and listing service for innovative or previouslyuncertified products. Manufacturers submit products fortesting at an approved laboratory to meet the criteria ofeither a CCMC Evaluation Directive if there is an existingapplicable standard, or a CCMC Technical Guide written fornew products for which no standards exist. Products coveredby a certification program recognized by the StandardsCouncil of Canada are not evaluated by CCMC.

The CCMC publishes and distributes evaluations and listingsin separate volumes. The listings are renewed annually andreviewed a minimum of once every three years. The reviewscover in-plant quality control programs, installation andmaintenance instructions, guarantees and warranties as wellas product identification and performance. However, CCMCdoes not carry out ongoing in-plant inspection and qualityassurance checks.

(CCMC) which, under the man-agement of IRC, has a more directinput into the NBCC developmentprocess.

During the last two years of the1995 code-change cycle, concernsarose within the CCBFC regard-ing a number of issues affectingthe future of model codes inCanada. These included:

• international trade and itseffect on manufacturers andregulators

• need to expand scope of codes to include such things as envi-ronmental and other societalissues, commissioning and lifecycle considerations

• need to limit scope of the code tothe basics of health and safetyand structural sufficiency

• increasing complexity of codes

• impact of codes on cost toindustry and the public

In 1995, the CCBFC approved astrategic plan intended to dealwith Canadian needs for buildingand fire regulations.

As a result, there were six majorgoals identified for the CCBFC.These are (in order of priority):

• Goal 1. To provide national andmodel codes that meet the needsof all code users in Canada

• Goal 2. To have future nation-al model codes adopted withoutmodification by all authoritieshaving jurisdiction in Canada

• Goal 3. To have uniform inter-pretation and understanding ofcode requirements throughoutCanada

• Goal 4. To have a responsive,objective and effective codedevelopment system

• Goal 5. To strengthen theCommission’s role

• Goal 6. To be substantially self-funding

As part of the strategy aroundthe first goal, it was agreed thatone major objective should bethat “all model codes be current,understandable, justifiable, logi-cal, flexible and co-ordinated.” To achieve this objective, it wasfurther agreed that an “objective-based code structure, reflectingidentified needs” be developed. Atarget date of the year 2001 waschosen.

A CCBFC task group on Objective-Based Codes began its work inearly 1996 on the development ofthe plan for transforming thenational model codes into anobjective-based framework.

As part of this transformation,the activities of all the currentStanding Committees have beensignificantly curtailed to onlyaddress issues having significanteconomic or safety implications.Where such issues arise, changesin the current 1995 NBCC wouldbe considered.

New Standing Committee struc-tures developed by the task groupwill be in place by the Fall of 1996.The goal is to have a set of interimsupport documents in 1998 that willbe based on the intent of the current(1995) Codes and identify the majorobjectives and sub-objectives of theCode. In 2001 the objective-basedcode document will be completed by


identifying functional require-ments and the various approvedsolutions which could includeeither prescriptive or performancesolutions (see insert).

For complete information on thetopic and work by the CCBFCtoward this objective-based code,readers may obtain copies of thefollowing documents from theSecretary of the CCBFC:

BUILDING THE FUTURE TheStrategic Plan of the CanadianCommission on Building andFire Codes 1995 - 2000

Possible Measures to Implementthe Strategic Plan of the CCBFC

Objective Based Codes: A NewApproach For Canada

CCBFC Strategic Plan and Objective Based Codes 25

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Sample Glossary of Terms

Objective-based Code — A code with a structure based on a hierarchy of objectives and sub-objectives.

Objective — A statement of the outcome that compliance with acode or part thereof is expected to achieve.

Sub-objective — One of a group of related objectives, the satisfactionof which contributes to satisfying a related higher level objective.

Functional Requirement — A detailed sub-objective at the highestlevel in the hierarchy at which the objective can be expressed inquantitative terms.

Approved Solution — An expression of one or more means deemed to satisfy a functional requirement or higher level objective. Such expression may be in the form of a prescriptive solution or a performance solution.

Prescriptive Solution — A specific statement of building elements(materials, components, assemblies, systems or equipments) thatcan be used and/or procedures that can be carried out to satisfy theterms of a functional requirement.

Performance Solution — A statement of the level of performancethat a building element (material, component, assembly, system or equipment) or procedure must provide to satisfy the terms of afunctional requirement. A performance solution specifies theaspect of the element’s performance that is being established, themethods that are used to measure performance and the criteriathat are used to evaluate success or failure.Source: Objective Based Codes; A New Approach For Canada, NRCC, Institute for Research in Construction, Ottawa, February, 1996.


Chapter Summary

The National Building Code of Canada is a highly regardedmodel building code. Its origins are deeply entrenched withinCanadian history and culture and a need to house the growingpopulation of Canada safely and economically.

Historical events have shaped many of the health and safetyrequirements of the NBCC.

Worldwide, codes are moving toward more performance-basedrequirements. The NBCC is working toward an objective-basedcode by the year 2001. This approach will allow the implementa-tion of various design and construction methods as long as theycan meet the clearly stated objectives. The code will still detailprescriptive solutions that comply with these objectives.

2Building with Wood2.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.2 Structural Systems in Wood . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Wood-Frame Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Heavy Timber Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.3 Wood in Noncombustible Buildings . . . . . . . . . . . . . . . . . . . . 39

Wood Furring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Fire Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Window Sashes and Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Combustible Cladding and Fascias . . . . . . . . . . . . . . . . . . . . . . . 42

Millwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Flooring Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Wood Partitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Stairs and Storage Lockers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Wood Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Wood was one of the earliest materials used in construction. Its advantages are obvious. Inaddition to being in ample supply,wood’s advantages include:• renewable supply• strength in both tension and

compression (stronger thansteel by weight)

• easily worked with simple tools• extremely flexible• unparalleled warmth and

beauty

Wood has another inherent property: it burns.

After some of the conflagrationsexperienced during the last century,legislators sought to limit the use ofwood-frame construction in favorof fire-resistive stone or brick con-struction. However, as J. GroveSmith pointed out in his 1918report of the Commission ofConservation, Fire Waste inCanada:

The typical “fireproof”building, having merelyincombustible floors, roofsand walls, cannot control a conflagration any morethan can an ordinary brickbuilding with a good roof. Aconflagration moves laterallyand a “fireproof” building inits path, as evidenced inmany of the larger fires, ismerely a crate which holdsup the fuel contents in posi-tion for free burning. Thecontents in buildings makeup the bulk of property loss,and repeated experience

shows that no building canwithstand the heat due tothe burning of a large quan-tity of merchandise.

Early building regulations wereintended to protect property onpurely economic grounds; ownerswanted to protect their invest-ment against fire in adjacentproperties. As buildings grewtaller, this became imperative.The idea of a building like theEmpire State collapsing on adja-cent properties understandablyraised concern.

Initially, structural fire resistancewas given paramount importance.Later, the safety of the occupantsand firefighters became a primaryobjective of building regulations.

Even materials that do not sustainfire do not guarantee the safety ofa structure. Steel, for instance,quickly loses its strength whenheated and its yield point decreasessignificantly as it absorbs heat,endangering the stability of thestructure (Figure 2.1). An unpro-tected, conventional open-web steeljoist system will fail in less than 10 minutes under standard fireexposure test methods, while a con-ventional wood joist floor systemcan last up to 15 minutes.

Even reinforced concrete is notimmune to fire. Though concretestructures have rarely collapsed,concrete will spall under elevatedtemperatures, exposing the steelreinforcement and weakeningstructural members.

Many varietiesof wood componentscreate structuralforms

General Information 29

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2.1 General Information

It is recognized then, that there isreally no such thing as a fireproofbuilding. Fires can occur in anytype of structure. The severity of afire, however, is contingent on theability of a construction to:• confine the fire• limit its effects on the sup-

porting structure• control the spread of smoke and

gases

To varying degrees, any type ofconstruction can be designed as asystem, that is, a combination ofconstruction assemblies, to limitthe effects of a fire. This allows

occupants sufficient time to escapethe building and for firefightersto safely reach the seat of the fire.

Occupant safety also depends onother parameters such as detectionand exit paths, and the use of auto-matic fire suppression systemssuch as sprinklers. These conceptsform the basis of the NBCC andare further explored in Chapter 3.

This chapter discusses the mostcommon types of wood structuresused in Canada as well as the uses of wood in noncombustiblebuildings.

FIGURE 2.1

Steel losesstrength at elevated temperatures


1.0

0.8

0.6

0.4

0.2

200 400 600

Temperature T(˚C)

Rat

io o

f st

ress

or

mo

du

lus

of

stee

l at

T˚C

to

th

e sa

me

at 2

0˚C

800 1000

yield stress ratio

modulus ofelasticity ratio

Source: Fire Engineering Design Guide, University of Canterbury, New Zealand, 1994

Structural systems in wood can be divided into wood-frame andheavy timber construction.

These two types of constructionhave important differences. Theyrelate to:• the size of the wood members• the methods of assembly• the degree to which they

must be combined with othermaterials to achieve fire-safeconditions

The type of construction permitted,wood-frame, heavy timber or non-combustible depends on buildingsize and use. Chapter 4 describesbuilding classification according tooccupancy, building height and area.

WOOD-FRAME CONSTRUCTION

Most houses in Canada are wood-frame construction. This methodof construction uses lumber38mm thick, in depths from89mm to 286mm, and membersare spaced at a maximum of600mm on centre.

Wood-frame construction is gen-erally regulated by Part 9 of the NBCC, Housing and SmallBuildings. However, it can also be used for Part 3 buildings permitted to be of combustibleconstruction.

In such cases, the span tables inPart 9 cannot be used since Part 3requires structures to be engineered

FIGURE 2.2

Wood-frameconstruction

Structural Systems in Wood 31

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2.2 Structural Systems in Wood

in accordance with Part 4, StructuralDesign. Part 4 requires wood struc-tures to be designed in accordancewith Canadian StandardsAssociation (CSA) Standard O86.1,Engineering Design in Wood —Limit States Design. For designmethods and tables see the WoodDesign Manual by the CanadianWood Council.

The span tables in Part 9 are calculated based on criteria devel-oped from years of experience.

[A-9.23.4.2.(2)] In the 1990 NBCC,a vibration control criteria wasadded to the strength and deflec-tion criteria for the span tables.Vibration control is based on thefloor as a system and takes into

account practices such as bracingand gluing. This criteria wasdeveloped to reduce the likelihoodof springy floors. Vibration crite-ria should be applied to all floorsystems for Part 9 buildings.

In the 1995 NBCC, more tableswere added and expanded to covera greater variety of constructions.

Though the structure of a modernwood-frame building may be madeentirely of wood, protective finishessuch as gypsum wallboard can beapplied to the framing to providefire resistance where required.

A fire-resistance rating is deter-mined by the amount of time thatan assembly resists the passage

FIGURE 2.3

Heavy timberconstruction


of heat and flames. This concept isexplained in Chapter 5. Wood-frameassemblies can economically bemade to resist the effects of a firefor up to two hours through the useof appropriate materials and con-struction methods. Experience hasproven this construction system tobe reliable and safe.

Wood frame floor and wall assemblies have been tested andare listed with varying degrees of fire resistance from 45 minutesto two hours.

HEAVY TIMBER CONSTRUCTION

Large dimension wood sectionshave an inherent resistance tofire. Wood burns slowly at approx-imately .6mm/minute. The charcreated on the wood surface as itburns helps protect and insulateunburnt wood below the charred

layer. The unburnt portion of athick member retains 85 to 90percent of its strength.

Hence, a wood member with alarge cross-section can burn for asignificant amount of time beforeits size is reduced to the pointwere it can no longer carry itsassigned loads.

Heavy timber construction isdefined as: “a type of combustibleconstruction in which a degree offire safety is attained by placinglimitations on the sizes of woodstructural members and onthickness and composition ofwood floors and roofs and by the avoidance of concealed spacesunder floors and roofs.”

Both solid-sawn and glue-laminatedmembers qualify under this defi-nition provided they have theminimum sizes given in Table 2.1.

TABLE 2.1

Minimumdimensions ofwood elementsin heavy timberconstruction


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Solid Sawn Glue-laminated RoundSupported Structural (width x depth) (width x depth) (diameter)Assembly Element mm x mm mm x mm mm

Roofs only Columns 140 x 191 130 x 190 180

Arches supported 89 x 140 80 x 152 –on the tops of walls or abutments

Beams, girders 89 x 140 80 x 152 –and trusses

Arches supported 140 x 140 130 x 152 –at or near the floorline

Floors, Columns 191 x 191 175 x 190 200floors plus Beams, girders, 140 x 241 130 x 228 –roofs trusses and or or

arches 191 x 191 175 x 190 –

Source: National Building Code of Canada, 1995.

Of course, they must be designed tocarry the expected loads and actualdimensions must conform to CSAStandard O141, Softwood Lumber.

Various types of connections areshown in Figure 2.4, with detailsfollowing in Figures 2.5 and 2.6.

[3.1.4.6.(1)] To satisfy heavy tim-ber requirements wood elementsmust be arranged in solid masseswith essentially smooth, flat sur-faces to avoid thin sections andsharp projections. This is to reduceto a minimum the surfaces whichcan be exposed to fire.

[3.1.4.6.(4)] For the same reason,when roof arches, trusses, beamsor girders are made from severalpieces, the connection elementsmust be a minimum of 64mmthick and be protected by sprin-klers. Where not protected bysprinklers, they must be built sothat they constitute a solid massor have the voids blocked off onthe underside by a continuouswood cover plate at least 38mmthick (Figure 2.6).


Detail ASuperimposed

column

Detail DStandard masonry

anchorage

Detail BBeam seated at

girderDetail C

Beam on girder

Detail IProtected truss joint

Detail EStandard beam to column

Detail FContinous column

Detail GAbutting beams on column

Detail HMasonry pilaster anchorage

Note:Refer to Figure 2.5 for Details (A) to (H) and Figure 2.6 for Detail (I)

FIGURE 2.4

Heavy timberconnections

FIGURE 2.5

Connectiondetails


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Detail A Typical superimposed column connection

Detail C Beam resting on top of girder

Detail F Typical continuouscolumn connection

Detail B Beam seated in metal hanger

Detail E Standard beam-to-column connection

Detail D Standard anchorage to masonry wall

Detail G Beam-to-column connection where beams abut over column

Detail H Beam to masonry pilaster anchorage

FIGURE 2.6

Detail IBuilt-up truss joint

FIGURE 2.7

Floor decks


Option A Option B

Blocking

Diagonal Chord

Cover Plates

Diagonal Chord

19mm min. T&G lumber

64mm min. T&G plank

Tongued and Grooved (T&G) Plank

64mm min. splined plank

12.5mm min. T&G plywood or waferboard

Spline

19mm min. T&G lumber

89mm x 38mm min. plank

Spiked Plank on Edge

Splined Plank

[3.1.4.5.] In addition to minimummember size, a number of otherNBCC requirements are intendedto ensure that the advantages ofheavy timber construction are not affected by poor assembly.When these requirements aremet, the NBCC considers heavytimber construction as equivalentto 45-minute rated combustibleconstruction (Chapter 5).

In sprinklered buildings permittedto be of combustible construction, nofire-resistance rating is required forthe roof assembly or its supports. In these cases, a heavy timber roofassembly and its supports would nothave to conform to the minimumdimensions stipulated in the NBCC.

In the case of the use of heavy tim-ber in noncombustible construction,which is permitted in both sprin-klered and unsprinklered cases, theminimum dimensions must alwaysbe met. This is covered in greaterdetail in Chapter 4.

[D-2.11] It is possible for heavytimber construction to have a onehour fire-resistance rating. A cal-culation method for determiningthe fire-resistance rating of glue-laminated beams and columns isfound in Appendix D of the NBCC.It includes descriptions of wooddeck assemblies which can beassigned a one hour fire-resistancerating. This calculation method isdiscussed later in Chapter 5.

[3.1.4.6.(8)] To meet heavy timberrequirements wood columns mustbe continuous or superimposed

through all storeys. Types ofcolumns permitted include:

• solid sawn timber• glue-laminated elements• uniformly tapered poles

Superimposed columns must bealigned with the vertical axis ofthe column below. They must alsobe adequately anchored to thegirder or beam with brackets orother types of connectors suitablefor heavy timber construction.(for example, Detail A, Figure 2.5)

[3.1.4.6.(11)] Heavy timber girdersand beams connected to continuouscolumns must be closely fitted andadjoining ends must be cross-tiedto ensure structural integrity.Similarly, intermediate beamsattached to girders must be closelyfitted.

[3.1.4.6.(10)] Heavy timber beamsand girders supported on masonrywalls must bear on wall plates,indented surfaces or hangers. Thisconnection must be designed sothat the collapse of the beam orgirder under fire conditions willnot cause the collapse of the wall;this is particularly important inthe case of firewalls.

[3.1.4.6.(5)&(6)] Heavy timberfloors are usually constructedwith solid sawn planks. Whenlaid flat, they must be tongue-and-groove, or splined. Splinedplanks are held together by stripsof wood called splines, which areinserted into grooves cut intoopposing edges of abutting planksto form a continuous joint.


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Planks laid on edge must bespiked together. Planks must belaid so that joints occurring in themiddle of a span are staggered; acontinuous line of end joints ispermissible only over points ofsupport, such as a beam.

Planks must then be covered by19mm tongue-and-groove lumberlaid across or diagonally, or by12.5mm phenolic-bonded plywood,oriented strandboard (OSB) orwaferboard. A 15mm clearance toend walls should be allowed forexpansion, and the gap betweenflooring and wall must befirestopped at the top or bottomwith lumber or plywood.

Figure 2.7 shows some typicaldetails of heavy timber floor deckconstruction.

[3.1.4.6.(7)] Heavy timber roofdecks may be constructed of 38mm(minimum) solid sawn planksassembled in the same way as forfloors, or of tongue-and-groovephenolic plywood at least 28mmthick. In addition to offering lowerinstallation cost, 28mm plywoodhas performed as well as tradi-tional heavy timber decking instandard fire tests.

Heavy timber construction is otherwise subject to the samerequirements for roof coveringsand concealed spaces as othertypes of construction.


The NBCC requires that somebuildings be of noncombustibleconstruction (Chapter 4).

Noncombustible construction isdefined as: a “type of constructionin which a degree of fire safety isattained by the use of noncom-bustible materials for structuralmembers and other buildingassemblies.”

Essentially, this type of construc-tion requires the use of noncom-bustible materials for the structureand certain assemblies.

Noncombustible is defined as:“meaning a material meets theacceptance criteria of CAN4-S114,Determination of Non-Combustibility in BuildingMaterials.”

Noncombustible construction is,however, something of a misnomer:it does not exclude the use of com-bustible materials but rather, itlimits their use. Some combustiblematerials can be used since it isneither economical nor practicalto construct a building entirelyout of noncombustible materials.

The allowance of combustiblecomponents is also partly due tothe severe test for determiningthe noncombustibility of materi-als which does not distinguishbetween degrees of combustibility.Based on this test, gypsum wall-board would not be permitted innoncombustible constructionsince it fails to meet one of thecriteria (flaming) and is thereforeconsidered a combustible product.

Many combustible materials areallowed in concealed spaces and in

areas where, in a fire, they are notlikely to seriously affect other firesafety features of the building.Restrictions are based on flame-spread and the amount of smokegenerated (for example, foamedplastic insulation).

The flame-spread rating andsmoke developed classification arecomparative indices of materials.These are explained in Chapter 3and further detailed in Chapter 6.

Wood is probably the most preva-lent combustible material used innoncombustible buildings.

It may be used as furring strips orfascia and canopies, cant strips, roofcurbs, firestopping, roof sheathingand coverings, millwork, cabinets,counters, window sash, doors, floor-ing, studs and even as wall finishes.

Its use in certain types of buildingssuch as tall buildings is slightlymore limited in areas such as exits,corridors and lobbies, but even there,fire-retardant treatments can beused to meet NBCC requirements.

[3.2.2.16.] In sprinklered noncom-bustible buildings not more than2 storeys in height, entire roofassemblies and the roof supportscan be heavy timber construction.Fire loss experience has shown,even in unsprinklered buildings,that heavy timber construction issuperior to noncombustible roofassemblies not having any fire-resistance rating.

In other noncombustible build-ings, heavy timber construction,including the floor assemblies, ispermitted without the buildingbeing sprinklered.

Wood in Noncombustible Buildings 39

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2.3 Wood in Noncombustible Buildings

Examples of permitted heavy timberconstruction uses in or, as an alter-native to, noncombustible buildingsare shown in Table 2.2.

Combustible materials which canbe used in buildings of noncom-bustible construction are listed inSubsection 3.1.5. of the NBCC.

A task group has been formedwithin the CCBFC StandingCommittee on Fire Protection tolook at introducing the concept of“degrees of combustibility” intothe NBCC. Using this method, theheat release rate of combustibleproducts and materials will beused to rank them and determineany limits on their use, struc-turally or otherwise. This is discussed further in Chapter 3.

The following brief description ofother uses of wood permitted innoncombustible buildings givessome indication of its versatility.

WOOD FURRING

[3.1.5.6.] Wood is particularlyuseful as a nailing base for differ-ent types of cladding and interiorfinishes. The NBCC allows woodfurring strips to be used to attachinterior finishes such as gypsumwallboard, provided:

• the strips are fastened to noncombustible backing or recessed into it

• the concealed space created bythe wood elements is not morethan 50mm thick

• the concealed space created bythe wood elements is firestopped

Experience has shown that a lack of oxygen in these shallowconcealed spaces prevents rapiddevelopment of fire.

TABLE 2.2

Permitted uses of heavy timberconstruction in or as an alternative tononcombustiblebuildings


OCCUPANCY HEIGHT SPRINKLERED1 PERMITTED USES

Group A, Div 1[3.2.2.21.] 1 Storey Yes Roof, floors and supports

Group A, Div 3[3.2.2.30.] 2 Storeys No Roof and its supports

Group A , Div 3[3.2.2.31.] 2 Storeys Yes Roof and its supports, arches

supporting floors

Group A, Div 4[3.2.2.35.] Not regulated No Roof and its supports

Group F, Div 1[3.2.2.64.] 3 Storeys Yes Roof, floors and supports

Group F, Div 3[3.2.2.80.] 1 Storey No Roof, floors and supports

Note 1 Article 3.2.2.16. permits roof assemblies and the supports to be heavy timber construction in any sprinklered noncombustible building not more than two storeys in height.

[3.1.5.3.(4)] The NBCC also per-mits wood nailer strips on parapets,provided the facings and any roofmembrane covering the facings areprotected by sheet metal. Thisrelaxation of earlier regulationswas introduced because it was con-sidered that a nailing base such asplywood or oriented strandboard(OSB) does not constitute an unduefire hazard.

FIRE STOP

[3.1.5.2.(1)(d)] Wood is generallyused for firestops in combustibleconstruction, but it may also beused in noncombustible assem-blies. However it must meet thecriteria for firestops when theassembly is subject to the stan-dard fire test used to determinefire resistance described inChapter 4.

[3.1.5.3.(2)] Wood is also permittedas a firestop material for dividingconcealed spaces into compartmentsin roofs of permitted combustibleconstruction. Firestops are describedin Chapter 5.

ROOFS

[3.1.5.3.(2)&(3)] In the installationof roofing, wood cant strips, roofcurbs, nailing strips are permittedin noncombustible construction.Roof sheathing and sheathing sup-ports of wood are also permittedprovided:• they are installed above a

concrete deck• the concealed space does not

extend more than 1m above thedeck

• the concealed roof space is com-partmented by firestops

• openings through the concrete deck are located innoncombustible shafts

• parapets are provided at thedeck perimeter extending at least 150mm above thesheathing

The noncombustible parapets andshafts are required to prevent roofmaterials igniting from flamesprojecting from openings in thebuilding face or roof deck.

[3.1.5.3.(1)] The NBCC alsorequires buildings that must be ofnoncombustible construction tohave roof coverings of Class A, Bor C (Chapter 6). In such cases, theuse of fire-retardant treated woodshakes and shingles on slopedroofs is allowed.

WINDOW SASHES AND FRAMES

[3.1.5.4.(5)] Wood sashes andframes are permitted providedeach window is separated fromadjacent windows by noncom-bustible construction and meets alimit on the aggregate area ofopenings in the outside face of afire compartment.

Glass typically fails early duringa fire, allowing flames to projectfrom the opening and thereby cre-ating serious potential for thevertical spread of fire. Therequirement for noncombustibleconstruction between windows isintended to limit fire spreadalong combustible frames closelyset into the outside face of thebuilding.


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COMBUSTIBLE CLADDING AND FASCIAS

[3.1.5.5.] The 1995 NBCC furtherrelaxed the rules on the use ofcombustible claddings and sup-porting assemblies on certaintypes of noncombustible buildings.

Specifically, the use of wall assem-blies containing both combustiblecladding elements and non-load-bearing wood framing members isallowed (Figures 2.8 & 2.9).

These wall assemblies can be usedas in-fill or panel type wallsbetween structural elements, or

FIGURE 2.8

Wood frameexterior wall innoncombustibleconstruction


Concrete floor slab or steel deck

Ceiling hanger

Noncombustible suspended ceiling

Non-loadbearing exterior wood framewall, studs @ 400mm O.C.

Gypsum wallboard

Vapour barrier

Siding:

Exterior gradeGypsum wallboard

Glass fibreinsulation

Concrete floor slab

Notes:1. Example of wood frame non-loadbearing exterior wall section permitted in buildings required to be of noncombustible construction.2. Siding and exterior grade gypsum wall board can be replaced with exterior grade fire retardant treated wood siding when phenolic foam insulation is used in the stud cavities.

- Vinyl- Brick- Metal

be attached directly to a loadbear-ing noncombustible structuralsystem. This applies in unsprin-klered buildings up to threestoreys and sprinklered buildingsof any height.

The wall assembly must satisfythe criteria of a test that deter-mines its degree of flammabilityand the interior surfaces of thewall assembly must be protectedby a thermal barrier (for example,12.7mm gypsum wallboard) tolimit the impact of an interiorfire on the wall assembly.

These requirements stem fromfull-scale IRC tests that indicatedthat certain wall assemblies con-

taining combustible elements donot promote fire spread beyond alimited distance.

[3.1.5.5.(1)] The ULC test stan-dard, CAN/ULC-S134, StandardMethod of Fire Test of ExteriorWall Assemblies is referenced inthe NBCC. Each assembly must betested in accordance with thisstandard to confirm compliancewith fire spread and heat fluxlimitations specified in the NBCC.

[3.1.5.5.(1)[&]3.2.3.7.(9)]Combustible cladding assembliesthat meet the requirements of thetest are permitted to be used innoncombustible construction

FIGURE 2.9

Wood stud framing in exterior wall ofnoncombustiblebuilding


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where spatial separation require-ments in Subsection 3.2.3. of theNBCC permit noncombustiblecladding, and, more than 10% ofunprotected openings is allowed.

Combustible cladding systems areexcluded for cases where the unpro-tected openings cannot exceed 10%because the fire research used todevelop these requirements did notconsider the impact of the com-bustible cladding assemblies on firespread to adjacent buildings.

[3.1.5.5.(5)] Fire-retardant treatedwood (FRTW) decorative claddingis permitted on first floor canopyfascias. In this case, the wood mustundergo accelerated weathering

before testing to establish theflame-spread rating. An FSR of 25 or less is required.

MILLWORK

[3.1.5.7.(1)] Wood millwork such as interior trim, doors and doorframes, show windows and frames,aprons and backing, handrails,shelves, cabinets and counters are also permitted in noncom-bustible construction. Becausethese elements contribute minimally to the overall fire hazard it is not necessary to restrict their use.

FIGURE 2.10

Raised woodfloor


Wood joist or truss

Concrete floor slab

Firestop area 10m2

50 - 300mm

Wood flooring

FLOORING ELEMENTS

[3.1.5.8.(4)] Combustible sub-flooring and finished flooring,such as wood strip or parquet isallowed in any noncombustiblebuilding, including high rises.Finished wood flooring is not amajor concern. During a fire, theair layer close to the floor remainsrelatively cool in comparison withthe hot air rising to the ceiling.

[3.1.5.8.(2)] Wood supports forcombustible flooring are also permitted provided:• they are at least 50mm but no

more than 300mm high• they are applied directly onto

or are recessed into a noncom-bustible floor slab

• the concealed spaces arefirestopped (Figure 2.10)

This allows the use of wood joistsor wood trusses, the latter provid-ing more flexibility for runningbuilding services within the space.

[3.1.5.8.(1)] Stages are normallyfairly large and considerablyhigher than 300mm which createsa large concealed space. Becauseof this, wood stage flooring mustbe supported by noncombustiblestructural members.

WOOD PARTITIONS

Wood framing has many applica-tions in partitions in both low riseand high rise buildings required tobe of noncombustible construction.The framing can be located in mosttypes of partitions, with or withouta fire-resistance rating.

[3.1.5.12.(1)] Wood framing andsheathing is permitted in parti-tions, or alternatively, solid lumber partitions at least 38mmthick (seldom used) are permitted,provided:

• the partitions are not used in acare or detention occupancy

• the area of the fire compartment,if not sprinklered, is limited to600m2 (unlimited in a floor areathat is sprinklered)

• the partitions are not requiredby the Code to be fire separations

[3.1.5.12.(2)] Alternatively, woodframing is permitted in partitionsthroughout floor areas, and can beused in most fire separations withno limits on compartment size ora need for sprinkler protectionprovided:

• the building is not more thanthree storeys in height


• the partitions are not installedas enclosures for exits or verti-cal service spaces

[3.1.5.12.(3)] Similarly, as a finaloption, wood framing is permittedin buildings with no restrictionon building height provided:

• the building is sprinklered


• the partitions are not installedas enclosures for exits or vertical service spaces

• the partitions are not used asfire separations to enclose amezzanine


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These changes in the 1995 NBCCare based on the performance offire rated wood stud partitionscompared to steel stud partitions.This research showed similar per-formance for wood or steel studassemblies.

The increase in the amount ofcombustible material permittedwas not large compared to whathad been permitted in previouseditions of the NBCC. In manycases, the framing is protectedand only burns later in a fire onceall combustible contents havebeen consumed by which time thethreat to life safety is not high.

The exclusion of the framing incare and detention occupanciesand in applications around criti-cal spaces such as shafts and exitsare applied to keep the level ofrisk as low as practical in theseapplications.

STAIRS AND STORAGE LOCKERS

[3.1.5.9.[&]3.1.5.13] Stairs within a dwelling unit can be made ofwood as can storage lockers in residential buildings. These arepermitted as their use is notexpected to present a significantfire hazard.

WOOD FINISHES

The use of interior finishes ismostly regulated by restrictions on their flame-spread rating.However, where finishes are usedas protection for foamed plasticinsulation, they are required to actas a thermal barrier (Chapter 6).

[3.1.13.2.] Wood finishes notexceeding 25mm in thickness andhaving a flame spread rating(FSR) of 150 or less may be usedextensively in noncombustiblebuildings, not considered a highbuilding. They may be used onwalls both within and outsidesuites.

Some restrictions do apply in certain areas of a building. Thearea permitted to have a FSR of 150 or less is limited as follows:• in exits — only 10% of total

wall area• in certain lobbies — only

25% of total wall area• in vertical spaces — only

10% of total wall area

[3.1.5.10.(3)] The use of wood finishes on the ceilings in non-combustible buildings is muchmore restricted, but not totallyexcluded. In such cases, the flamespread rating must be 25 or less.In certain cases, ordinary woodfinishes can also be used on 10% of the ceiling area of any one firecompartment, as well as on theceilings of exits, lobbies and corridors.

[3.1.4.4.[&]3.1.5.10.] Fire retardanttreated wood (FRTW) must beused to meet the most restrictivelimit of FSR 25. Consequently, it ispermitted extensively throughoutnoncombustible buildings. Theonly restriction is that it cannotexceed 25 mm in thickness whenused as a finish, except as woodbattens on a ceiling, in which caseno maximum thickness applies.


Fire retardant coatings applied towood and other combustible mate-rials do not meet the 25 flame-spread rating limits for walls orceilings in noncombustible build-ings, even if it has been tested andshown to provide a 25 flame-spread rating on a combustiblesubstrate such as plywood.

[3.1.5.10.(2)[&](3)] This is becausethe NBCC requirement for interi-or finishes in noncombustiblebuildings requires that the sur-face flame spread rating be applic-able to any surface of the materialthat may be exposed by cuttingthrough the material. Fire retar-dant treated wood is exemptedfrom this requirement because thetreatment is applied through pres-sure impregnation. Fire retardantcoatings are not exempt becausethey are surface applied only.

[3.1.13.6.(1)] The FSR 75 flamelimit for interior wall finishes incertain corridors does not excludeall wood products. Western redcedar, amabilis fir, western hem-lock, western white pine andwhite or sitka spruce all haveflame-spread ratings at or lowerthan 75. (Chapter 6)

[3.1.13.6.(2)] Corridors requiringFSR 75 include:• public corridors in any

occupancy• corridors used by the public in

assembly or care or detentionoccupancies

• corridors serving classrooms• corridors serving sleeping

rooms in care and detentionoccupancies

However, alternatively, the wallsmay be finished with wood prod-ucts with a FRS of 150 or less onthe lower half when the buildingis not sprinklered and the finishon the upper half has a FSR of 25.

[3.1.13.6.(3)] If these corridors arelocated in a sprinklered building,wood finishes having FSR 150 orless may be used to cover theentire wall surface.

[3.1.13.7.] In high buildings regulated by NBCC Subsection3.2.6., wood finishes are permittedwithin suites or floor areas much as for other buildings ofnoncombustible construction.However, certain additional restrictions apply for:• exit stairways• corridors not within suites• vestibules to exit stairs

• certain lobbies

• elevator cars

• service spaces and servicerooms

These additional restrictions are waived, except for Group Boccupancies and elevator cars,when the building is sprinklered(Chapters 6 and 10).

Table 6.3 in Chapter 6 summa-rizes the requirements for interiorfinishes including glazing andlighting elements.


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Chapter SummaryWood is a versatile construction material which may be usedto provide structural and fire protection security as well asaesthetic appeal. Both heavy timber and wood-frame construc-tion are governed by the National Building Code of Canada.

Wood has numerous applications in buildings of noncom-bustible construction. This is because modern building regulations do not rely solely on the use of noncombustiblematerials to achieve an acceptable degree of fire safety.

3The NBCC :Assumptionsand Objectives3.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

3.2 The NFPA Fire Safety Concepts Tree . . . . . . . . . . . . . . . . . . . . 53

3.3 Limiting Fire Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

The Noncombustibility Concept . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Flammability of Interior Finishes and Building Contents . . . . . . . . 58

3.4 Containing the Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Fire Compartments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Preventing Conflagrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

3.5 Suppress the Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

3.6 Managing the Exposed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

North American building codesare based on certain fundamen-tal principles and assumptions.

The North American approach to fire safety is predicated on thefact that fire-resistive designalone cannot ensure an accept-able level of safety. The contentsof buildings, which are generallynot subject to building regula-tions, can create a fire hazard fargreater than the building itself.

A study performed by Consumerand Corporate Affairs Canadashowed that the materials thatare by far the most likely ignitionsources are flammable or com-bustible liquids, such as gasolineor cooking oil.

The next most likely ignitionsource is furniture and furnish-ings. Although they account forfewer fires than flammable orcombustible liquids, they areresponsible for almost a quarterof the total number of fire deaths.

Because of this high hazard, somefurniture and furnishings areregulated under the HazardousProducts Act. This Act limits the ignitability of the materialsused in such items as mattresses,curtains and carpets.

Fire safety in buildings can beattained through different methods.The simplest is to adhere to strictdesign and construction require-ments (prescriptive requirements).

These requirements state exactlywhich materials and constructionmust be used for every componentof the building and thus offer verylittle flexibility. They can proveparticularly difficult to adhere toin buildings with unusual charac-teristics and in the rehabilitationof older buildings.

Performance-based requirements setthe level of performance that mustbe achieved by a system. A buildingsystem involves more than methodsof assembly. All the interactivedesign elements that are intended tosatisfy given fire safety objectives ina building make up the system.

Performance-based requirementsoffer a greater level of flexibility tothe professionals involved in build-ing design and construction. They dorequire, however, the measurementof the relative performance of vari-ous building components and designfeatures. This can be difficult.

It is possible to evaluate the levelof fire safety by considering theimpact of a material or designsolution on the overall system.

Business andmedium hazardindustrial complex inwood


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This process is called fire safetysystems analysis, a methodical,step-by-step method for solvingfire safety problems.

One such method or model, isthe National Fire ProtectionAssociation (NFPA) Fire SafetyConcepts Tree. It was designed bythe NFPA Committee on SystemsConcepts for Fire Protection inStructures. This model is nowmaintained and updated by the NFPA Standards Council.

The assumptions and objectivesunderlying the NBCC require-ments are consistent with thismodel. The Fire Safety ConceptsTree will be used as a tool forillustrating the NBCC approachthroughout the subsequent chapters.

For additional information, referto the standard NFPA 550, Guideto the Fire Safety Concepts Tree,1995 Edition, available from the National Fire ProtectionAssociation.


The NFPA Fire Safety ConceptsTree, (Figure 3.1), shows the ele-ments that should be consideredfor fire safety in buildings andthe relationship between them.

The branches are connected bytwo types of gates:• “or” gate means any branch

will achieve the objective of the box above it

• “and” gate means all branchesmust be satisfied to ensure success

A lower level is not less importantthan the one above: it representsmeans for satisfying that higherlevel.

In theory, any branch will achievethe given objective if it is 100%effective. In reality, no one systemmay be relied upon to achieve

100% success. A fire safety systemwill necessarily rely on a combi-nation of measures.

The Canadian Codes follow themodel in principal but, to increasereliability, will require bothbranches of an “or” gate to be satisfied.

At the first level, overall firesafety objectives can be meteither by preventing fire ignitionor by managing the impact of afire.

The conditions of the Prevent Fire Ignition branch essentiallyconstitute the requirements of the National Fire Code of Canada.Though its strict enforcement cangreatly reduce the possibility ofignition, it cannot provide assur-ances that a fire will never occur.

The NFPA Fire Safety Concepts Tree 53

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3.2 The NFPA Fire Safety Concepts Tree

Contain Fire by

Construction

Control Combustion

Process

SuppressFire

SafeguardExposed

Limit Amount Exposed

ManageExposed

ManageFire

PreventFire

Ignition

Manage Fire

Impact

FireSafety

Objectives

Automatically Suppress

Fire

ManuallySuppress

Fire

Control Fuel

Controlthe

Environment

ControlMovement

of Fire

ProvideStructuralStability

DefendExposedin Place

MoveExposed

CauseMovement of Exposed

ProvideMovement

Means

Provide Safe

Destination

NFCC

“and” gate

NFCC

NFCC

“or” gate

FIGURE 3.1

NFPA FireSafetyConcepts Tree

The NBCC follows the path of theManage Fire Impact branch of theNFPA tree. It is assumed that afire will occur and means must beprovided to limit its consequences.

This is achieved by the next levelof the tree by:• managing the fire, or• managing the exposed

(the occupants)

The NBCC requirements aredesigned to satisfy both theManage Fire and Manage Exposedbranches. A number of measures inthe next lower levels are requiredto achieve these objectives.

These measures are intended toprotect the occupants and allowsufficient time for them to escape.The amount of time available willdepend on:• how quickly they are alerted

(fire alarm and detection system)

• the rate at which the fire grows to hazardous levels (combustibility and flammability of building contents)

• the effectiveness of the roomboundaries (walls, floor andceiling) to resist the passage of heat, smoke and flames

• the ability of loadbearing elements to resist collapse (fire separation and fire resistance)

• the number, configuration anddegree of protection of means of egress leading to the outside

• suppression of the fire

Obviously, the Suppress Firebranch must also be satisfied forthe system to be effective. TheNBCC contains requirements for automatic and manual suppression systems. Access forfirefighters and provisions fortheir safety during suppressionoperations are also included.

Again these requirements arebased on certain assumptions(availability of firefighting capabilities) which will be discussed later in this chapter (see also Chapter 9).

To summarize, the safety of theoccupants depends on means to:

• limit fire growth

• contain the fire and providestructural stability

• alert occupants

• provide means of egress to a safe destination

• suppress the fire

• allow access and time for firefighting

A brief discussion of each of these objectives follows.


Controlling the combustible contentof a building (Control CombustionProcess branch) plays a significantrole in managing a fire.

Regardless of what material is first ignited, the fact remainsthat if a fire, once ignited, spreadsand burns slowly, occupants canhave sufficient time to escape.

This is why the NBCC regulatesthe flammability and combustibil-ity of building materials. Theflammability refers to the propen-sity of a material to be ignited andsustain burning, while the com-

bustibility concerns the rate atwhich it burns, if ignited.

The NBCC also makes a distinc-tion between combustible andnoncombustible construction.

It is important to understand that in the NBCC, the term “noncombustible construction”does not infer that buildingassemblies are made entirely from noncombustible materials.

Noncombustible construction isdefined as: “a type of constructionin which a degree of fire safety

Limiting Fire Growth 55

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3.3 Limiting Fire Growth

Radiation

Hot Gas Layer

Plume

Air

Air

Air

Fire Growth in a RoomTo understand the measures outlined in this Chapter, it is useful to describe what happens when a fire occurs in a room. When an object is burning in an enclosed area,smoke rises to form a hot gas layer below the ceiling. These hot gases heat the ceilingand upper portion of the walls and thermal radiation from the hot layer, ceiling andwalls begins to heat all the objects in the room. Given sufficient oxygen, this heatingprocess can progress until all other combustible objects in the room reach their ignitiontemperature more or less simultaneously. At this point, every combustible object in theroom will burst into flames, a state referred to as “flashover.” Flashover occurs whenthe temperature of the hot upper layer of air in the room reaches 500 to 600°C (need-less to say, any occupants of the room would have perished long before this point).


The Noncombustibility Test

The noncombustibility of materials is determined by Underwriters' Laboratory ofCanada (ULC) standard S-114, Standard Method of Test for Determination ofNoncombustibility of Materials.

This test is conducted in a small, electrically heated furnace. Before the test, the furnace is heated to 750°C and stabilized to within 1°C for 15 minutes. The specimenis then placed in the sample holder and inserted into the furnace from below.

The test lasts 15 minutes, unless it is evident that the specimen has failed the testbefore that time. At least three specimens of a material must be tested.

Materials subjected to the test are considered noncombustible if:

• the mean of the maximum temperature rise (measured by an indicating thermocouple) for all specimens during the test does not exceed 36°C

• there is no flaming of any of the specimens after the first 30 seconds of the test

• the maximum loss of mass of any of the specimens during the test does notexceed 20%

Gas vent

200mm

290m

mIndicating thermocouple

Heating element

Sample

Controlling thermocouple

Refractory tubing

Insulating firebrick

Sheet metal

The Noncombustibility Test Furnace

is attained by the use of noncom-bustible materials for structuralmembers and other buildingassemblies.”

As outlined in Chapter 2, variouscombustible materials and sys-tems are permitted to be used innoncombustible construction. Thisis because the test which is used todetermine the noncombustibilityof materials is very different fromthat which determines the degreeto which a construction assemblywill withstand the effects of a fire(see Chapter 5 for an explanation of fire-resistance rating).

The noncombustibility test is onlyintended for the evaluation ofbasic building materials. The testdoes not apply to materials with adecorative coating or built-uplaminations of different mate-rials. (See “The NoncombustibilityTest” at left.)

[3.1.7.1.] On the other hand, thetest which determines fire resis-tance concerns the performance of an entire construction assemblyexposed to the effects of a fire for a specified duration, regardless ofwhether it is constructed of com-bustible or noncombustible mate-rials, or a combination of both.

THE NONCOMBUSTIBILITY CONCEPT

As can be seen from the descriptionof the noncombustibility test in theinsert, this is a severe pass-or-failtest.

A material is either found to becombustible or not: there is no mea-sure of the degree of combustibility.Consequently, noncombustiblematerials are generally limited tomaterials such as: brick, concrete(without combustible aggregates),gypsum plaster, metals, glass andmost stones.

FIGURE 3.2

Post-fire interior


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Noncombustibility is an attributewhich is considered to limit firegrowth. If a material cannot beignited, it will not contribute tothe fire.

However, it is not the noncom-bustible items required for build-ing construction but rather thebuilding contents which contributethe most to fire growth. Hence, itcan be argued that requirementsfor noncombustibility relate moreto containing a fire than limitingfire growth.

The NBCC seldom requires specificnoncombustible materials; it reliesinstead on the definition of non-combustible construction to inferthat all materials used in the con-struction be noncombustible andthen proceeds to allow combustiblematerials for various components.

[3.1.5.5.] In general, noncom-bustible materials are requiredfor structural components and,with one exception (discussed inChapter 4), for exterior claddingin buildings required to be of non-combustible construction.

[3.1.5.2.(1)(b)] They are alsorequired to protect foamed plasticinsulation. The most commonlyused material for this purpose isgypsum wallboard which will notmeet the noncombustibility crite-ria. Its use is permitted, neverthe-less, because it has demonstratedsatisfactory performance in fireconditions.

Finally, noncombustible materialscan be used in certain instances(such as for ducts which penetrate afire separation) to waive otherrequirements (such as fire dampers).

FLAMMABILITY OF INTERIOR FINISHES AND BUILDING CONTENTS

The burning of the building con-tents is recognized as contributingthe most to fire growth in a roomor space.

However, the development of a firewill also be influenced by exposedbuilding materials such as walland ceiling finishes, light fixturesand trim, and decorative materialsin a room.

If walls and ceilings are involvedin a fire at an early stage and burntoo quickly, occupants could experi-ence great difficulty in escapingthe fire. This is why the NBCCimposes limits on the flame-spreadpotential of building materials.

[3.1.12.1.] Chapter 6 explains thetest method used to determine thesurface burning characteristics ofmaterials. The results of the testare used to assign a relative indexof the rate at which the materialburns, called flame-spread rating(FSR). This rating is based on twobenchmark materials, asbestosand red oak.

[3.1.13.] Generally, NBCC require-ments on interior finishes aredesigned to become more restrictiveas the space under considerationbecomes more important to theevacuation of occupants.

Interior finish materials with ahigher flammability will be per-mitted within individual suitesto give designers more decorativeflexibility.

Requirements become more restric-tive in areas such as corridors andother egress routes, because build-


ing occupants must necessarily usethese paths to move from the suitesto the exits. If the interior finishesburn rapidly in these areas, occu-pants could find themselves unableto reach the exits.

Requirements for exits are themost restrictive since they act ascollectors through which all occu-pants are funneled. Exits consti-tute the final link between thebuilding and a safe destination; a fire cannot be allowed to devel-op within these areas. (Wood finishes can meet all levels ofrequirements).

A fire does not always originatewithin a room. It may start in aconcealed ceiling space, or movefrom a room to that concealedspace through an opening in theassembly that separates the roomfrom the space.

Certain combustible materialsare permitted to be used in theconcealed spaces of buildings that are required to be of noncom-bustible construction. The NBCCplaces limits on the flame-spreadpotential of these materials. Italso sets limits on the amount ofsmoke that can be generated fromcertain building materials. Thisis termed the smoke developedclassification.

[3.1.13.7.] The smoke developed classification is particularlyapplicable to high buildings.These buildings have a tremen-dous potential for spreadingsmoke through the shafts thatrun the height of the building forstairs, elevators, pipes, ducts andother services. Temperature dif-ferentials between inside and outside air create a “stack effect”which causes shafts to act aschimneys, sucking air from thebottom of the building and pump-ing it into the higher floors.

The 1995 NBCC addresses thisproblem by requiring that sprinkler protection, one acceptedmethod of smoke control, be provided for all high buildings.Design of tall buildings is discussed in Chapter 10.

Controlling the movement of smokein tall buildings is very difficult.Even though sprinklering reducesthe potential losses in highrisebuildings, limits on smoke genera-tion are still imposed on interiorfinishes.


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Limiting the combustibility andflame-spread potential of materialssatisfies the Control CombustionProcess branch of the tree.

However, these measures will notensure that a fire will not developbeyond flashover. Other meansmust be provided to contain thefire, hopefully within the area of origin (the Contain Fire byConstruction branch). This isaddressed through compartmenta-tion, a concept used to control thehazards of a fully developed fire.

In a fully developed fire, the safety of the occupants within theroom of fire origin is no longer anissue. As outlined in the descrip-tion of a room fire, temperaturesin the room will have reached the point where no one can beexpected to survive.

The objective at this stage of afire is to retard its spread so thatthe other occupants of the build-ing have time to reach a place ofsafety. This allows firefighters

time to set up a staging area, perform rescue operations andsuppress the fire.

FIRE COMPARTMENTS

Fire compartments are areas of a building ranging in size from a single room to an entire floorarea. Physical barriers aroundthese areas such as walls andceilings are used to resist thespread of the fire for a period of time.

Fire compartment is defined as:“an enclosed space in a buildingthat is separated from all otherparts of the building by enclosingconstruction providing a fire separation having a required fire-resistance rating.”

[3.1.8.1.] Theoretically, a com-partment is like a box designed to contain the fire within its boundaries. To be effective, theseboundaries, called fire separations,must be continuous.

Containing the Fire 61

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3.4 Containing the Fire

FIGURE 3.3

Fire safetyrequirements must beaddressedearly in thedesign stage

[3.1.8.1.(2)] However, openings infire compartments are necessaryto allow access and to provide forthe passage of plumbing, electri-cal and other services. To main-tain integrity, every opening in afire separation must either be pro-tected by a closure, (a door orshutter) or other mechanismwhich blocks the opening. Forbuilding services, the gap betweenthe fire separation and the pene-trating object must be filled withfire-resistant material.

Considering that it may take overan hour to evacuate a 30-storeyoffice building, the importance of fire containment is apparent.

[3.4.3.] Stairways are normallydesigned to accommodate the evac-uation of occupants on a floor-by-floor basis; therefore, the widths ofexits are not cumulative, exceptwhere exits converge or serve anatrium (where all levels are expect-ed to evacuate simultaneously).

Occupants on floors other thanthe floor of fire origin must beprotected against the spread offire for at least the amount oftime required for the evacuation.This is why all floor/ceilingassemblies and stair enclosuresare required to be built as fireseparations. (See Chapter 8 for exit requirements.)

Fire separations and closuresmust normally have a knowndegree of resistance to fire(Chapter 5). The level of fire

resistance required for the assem-blies will depend on:• type of building• building height• occupancy

The occupancy will determine the severity of the fire which canbe expected considering the use of the building (see Chapter 4).

PREVENTING CONFLAGRATIONS

The Control Movement of Firebranch of the NFPA Fire SafetyConcepts Tree primarily looks atcompartmentation inside thebuilding.

[3.2.3.1.] However, it also extendsto the spread of fire beyond thebuilding of fire origin. In thisrespect, the NBCC includes provi-sions that are intended to pre-vent conflagrations by limitingthe proximity of buildings andthe number of openings in theirexterior walls.

In a fully developed fire, the glassin windows will break. A burningbuilding or compartment within abuilding will emit heat by radia-tion through these openings. Thisradiation could heat the exteriorof an adjacent building and causeit to ignite, spreading the fire toanother property.

The NBCC cannot impose restric-tions on adjacent properties, it can only control the building forwhich a building permit is beingrequested.


The position and number of open-ings in the exterior walls of eachbuilding are regulated in relationto the boundaries of the lot onwhich the building is erected. Thisprovides a fair set of rules for all.

Similar buildings located at equaldistances from the lot line will be subject to the same restrictionsregarding the construction of exterior walls and openings inthose walls. (Figure 7.2, page 233)

Containing the Fire 63

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FIGURE 3.4

Firefighter andthe aftermath

The NBCC contains requirementsintended to satisfy the SuppressFire branch of the tree. Some areaimed specifically at facilitatingfirefighting while others, such asthe provision of manual (stand-pipe and hose), and automatic(sprinklers) fire protection sys-tems, are associated with protect-ing occupants.

Significant changes were includedin the 1995 NBCC regardingmandatory sprinkler protectionfor many buildings. The major fac-tors considered in introducing thechanges related largely to the levelof risk expected in the buildings.

For example, loss experienceshowed the potential risk to bevery high in buildings occupiedfor the care and detention of peo-ple. The NBCC now requires allGroup B occupancies to be sprin-klered. Similarly, highrise build-ings present higher fire risk situa-tions, and sprinkler protection isnow required for all buildingsmore than six storeys in height.

[3.2.3.1.(5)[&[3.2.5.] The NBCCassumes that firefightingresources are available in theevent of a fire emergency, whetherthrough a paid fire department orvolunteers. The NBCC does notattempt to relate the size of abuilding to the capability of themunicipal fire department.

It is the responsibility of eachmunicipality to ensure that thesize and height of buildings donot exceed its firefighting capa-bilities and available water sup-ply. The minimum water supplyrequired depends on a number offactors including whether or notthe building is sprinklered.

[3.2.5.] Given these assumptions,the NBCC ensures that:

• firefighters have access to anystorey that is within reach ofaerial ladders

• firefighting vehicles can bepositioned so as to deploy theseladders and other vehicles

• buildings are within reach offire hydrants

Most fire departments in largecities have aerial ladders thatwill extend as high as six storeys,but truck ladders are availabletoday which will extend to some60m. In some buildings, such ashigh buildings, standpipes andhose systems are required so thatthe fire can be fought withouthaving to carry hose lines all the way up to the fire floor.

Chapter 9 explains in greaterdetail some of the important ele-ments in the NBCC to facilitatefirefighting.

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3.5 Suppress the Fire

Once a fire occurs, occupants ofthe building must evacuate asquickly as possible. For this tohappen, they must be alerted tothe danger.

The NBCC requires various meansof fire detection and alarm, basedon the severity of the threat tooccupants. Chapter 8 describesthese requirements.

In most buildings, detection devicesare required to be linked to an alarmsystem because occupants, in theirhaste to evacuate, cannot be reliedupon to phone the fire department oractivate a manual pull station.

Delays in alerting occupants ofdanger have caused many deaths.In the Winecoff Hotel fire, forinstance, with no automaticalarm system in the building, theinitial alarm was delayed and thefire department was not notifieduntil almost 30 minutes after thediscovery of the fire (Chapter 1).

Many areas of a building, (lockersin residential buildings, rooms forbuilding services, janitors' closets)are unoccupied most of the time.Automatic fire detection in suchareas can save precious minutes.

[3.4.2.1.] One of the basic premisesof the NBCC is that occupantsshould have a choice of two egressroutes to vacate the building incase one of the exits is blocked bythe fire.

A single exit may be permitted incases where it is considered thatthe use of the space, the numberof occupants and the distancewhich they must travel to reachthe exit will not create an unduehazard. The number and locationof exits depends on the number ofoccupants and the size of a floorarea. (Chapter 8)

Exit facilities are not particularlyinteresting to designers and ownersof buildings. They can constitute afair amount of economically unvi-able space as well as a securityproblem; too many points of accessand egress create an increasedoperational burden.

It is vital, however, to realizethat the provision of well pro-tected egress facilities can, inmany cases, make the differencebetween life and death for occupants.

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3.6 Managing the Exposed


Chapter SummaryThis Chapter examined the fire safety objectives of theNBCC which center on managing the impact of a fire in a building. The NFPA Fire Safety Concepts Tree was examined as a model to understand the concept.

The NBCC constitutes a set of minimum requirements. In some situations, the achievement of the fire safety objectives outlined in this Chapter may require measuresbeyond this minimum.

Experience has shown that fire safety is often misunder-stood by designers. Both they and their clients often assumethat by complying with the minimum requirements ofbuilding codes, fire safety will be achieved.

This is not always the case; neither the NBCC nor any other building code can anticipate every possible hazardousscenario.

Understanding the underlying objectives of the NBCCrequirements is the first step in being able to assess the expected level of fire safety. The CCBFC is developing an “objective-based code” which will clearly define the objectives. This will make understanding and complyingwith the intent of the NBCC simpler for designers.

Designers must consult many sources of information whichare available today to assess the fire safety of their designs.A number of firms specializing in fire protection engineer-ing offer evaluation and design services to ensure that firesafety is achieved at a reasonable cost.

4ConstructionRequirements4.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

4.2 Classification of Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Building Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Major Occupancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

4.3 Determining Construction Requirements . . . . . . . . . . . . . . . . 83

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Separation of Major Occupancies . . . . . . . . . . . . . . . . . . . . . . . . 85

Fire-Resistance Rating of Supporting Assemblies . . . . . . . . . . . . 87

Construction Requirement Options . . . . . . . . . . . . . . . . . . . . . . . 87

4.4 Sprinkler Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Changes in 1995 NBCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

4.5 Storeys Below Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Design Requirement Tables . . . . . . . . . . . . . . . . . . . . . . . 97–127

Building is defined as: “any struc-ture used or intended for supportingor sheltering any use or occupancy.”

This definition is fairly broad andcan encompass practically anystructure. Various attempts atdefining the word building moreprecisely have been unsuccessful:as the definition becomes moreaccurate, it becomes more difficultto apply.

There are definite advantages inkeeping the definition flexible forthose instances where a structurepresents a potential danger to thepublic but would not normally beconsidered a building. An oil refin-ery, for instance, does not have afloor area as defined in the NBCC,and so it would be impossible toapply exit requirements. On theother hand, there might be certainsections of the refinery, such asoffices, where it would be desirableto apply the requirements of Part 3.

The NBCC only controls those elements which are part of thebuilding construction (except forthe contents of atrium spaces).The classification of buildings orparts of buildings according totheir intended use accounts for:• the quantity and type of com-

bustible materials likely to bepresent (potential fire load)

• the number of persons likely tobe exposed to the threat of fire

• the area of the building• the height of the building

This classification is the startingpoint in determining whichrequirements apply to a particularbuilding.

This chapter will explain theprinciples and rationale for theclassification of buildings in theNBCC on the basis of occupancyand building size.

Classification dictates: • the type of construction• the level of protection• the degree of protection

between parts of a buildingthat are used for different purposes

These are required to ensure thesafety of the occupants and controlthe hazards to adjacent buildings.

The Design Requirement Tablesincluded at the end of this chap-ter summarize the fire protectionrequirements of NBCC Subsection3.2.2., which are based on buildingclassification.

ThompsonCommunityCentre,Richmond, B.C.


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The level of structural fireendurance and separation is basedon the expected severity of the firebased on occupancy and the sizeand height of the building. Theclassification used by the NBCCalso takes into account such factorsas the mobility of the occupantsand their state of alertness.

Obviously, the emergency evacua-tion of a theatre or hospital will be more difficult than that of anoffice building. NBCC Table3.1.2.1. shows the various groupsand divisions in which buildingscan be classified and examples areprovided in the NBCC Appendix.

The groups and divisions help todistinguish between various typesof risk. The list of the groups anddivisions and the reasoning

behind the classifications of occu-pancies are shown in Table 4.1.

As shown in Table 4.1, the impor-tant consideration in Groups A, B,C and D occupancies is protectionof occupants from the hazards ofthe occupancies, while the primaryconcern in Groups E and F is con-tainment of the fire within thatspace. For this reason, require-ments for fire separations betweenthese two groups of occupancieswill be more stringent thanbetween occupancies belonging tosimilar groups.

BUILDING SIZE

In order to determine therequirements for a building, bothoccupancy and building size are

FIGURE 4.1

Heavy timberskeleton of an arena

Classification of Buildings 73

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4.2 Classification of Buildings


TABLE 4.1

Classificationof buildings

Occupancy Group Division Risk Factors Examples

Assembly A Evacuation of considerable number of people, often from large spaces

1 • poor lighting conditions can theatreshinder evacuation

2 • good lighting conditions schools3 • well lit arenas

• low fire loads• large open spaces where

smoke can dissipate4 • open air assembly area bleachers

• low risk of being trapped

Care and B Acute evacuation problemsDetention because of restricted

mobility of occupants1 • occupant movement is res- penitentiaries

tricted by security measures2 • lack of occupant mobility hospitals

• require safe area to permit two stage evacuation

• need to contain fire to area of origin

Residential C • people may be sleeping apartmentswhen the need for emergency hotelsevacuation arises

• significant delays in people becoming aware of a fire and evacuating the building

• occupants must be protected while preparing to evacuate

Business D • occupants are fully alert offices• relatively low fire load• no major evacuation problems

Mercantile E • high combustible content departmentwhich can result in severe storesfire with heavy smoke

• occupants are aware• no unusual evacuation

problems

Industrial F 1 • highly combustible and flam- distilleriesmable or explosive substances

2 • medium hazard, no explosive factoriessubstances

3 • low hazard, can still have warehouseshigh fire load

required. Building size is charac-terized by both area and heightof a building. NBCC Subsection3.2.2. uses these parameters todetermine: • the type of construction (com-

bustible or noncombustible)• the level of fire protection

required for fire separations(fire-resistance rating)

• fire suppression requirements(automatic sprinklers)

Building AreaBuilding area is defined as: “thegreatest horizontal area of abuilding above grade within theoutside surface of exterior wallsor within the outside surface ofexterior walls and the centre lineof firewalls.”

It is not calculated on a floor-by-floor basis, but as the total areain plan view, or footprint of thebuilding (Figure 4.2).

It is important to note that firewalls may be used to reduce abuilding’s defined area. This isdemonstrated in the followingexample.

Example 4.1

Occupancy: apartment — Group CBuilding area: 1500m2

Building height: three storeysBuilding facing: two streetsSprinklers: none

Requirements — [3.2.2.44.] :• the building must be of non-

combustible construction • one hour fire-resistance rating

for floors and supportingassemblies

However, the building could bedivided in half with a firewall.Since the NBCC considers eachpart of a building separated fromthe rest by firewalls as a separatebuilding for the purposes of fireprotection, we now have:

Building area: 750m2

Requirements could then be [3.2.2.47.] :• the building could be of

combustible construction• 45 minute fire-resistance

rating for floors and supporting assemblies


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FIGURE 4.2

Determiningbuilding area

Elevation Plan

a a

b

Building Area = a x b

The economy of building withwood can easily offset the cost ofthe firewall.

Building HeightDetermining building height isslightly more complex because itis related to the number of storeysabove the first storey, which inturn is related to grade.

Grade is defined as: “the lowest ofthe average levels of finishedground adjoining each exteriorwall of a building.”

For a building on a relatively flatlot, determining grade level isfairly simple. But it can becomefar more difficult for large build-ings on irregular lots (Figure 4.3).

[2.1.6.2.] Where a residentialbuilding is set into a hillside it maybe divided by one-hour vertical sep-arations into compartments of up tothree storeys. These are then treatedas separate buildings to determinebuilding height. However, the totalbuilding area is used to determineconstruction requirements (Figure4.4). In addition, each section mustbe accessible to fire-fighters in con-formance with the requirements foraccess for firefighting (Chapter 9).

Once the level of grade has beenestablished, the first storey of thebuilding is the storey with its floorlevel not more than 2m above that.

Building height is defined as: “thenumber of storeys between the roofand the floor of the first storey.”


FIGURE 4.3

Determininggrade

Plan view

West elevationNorth elevationEast elevationSouth elevation

DefinedGrade

hwhnhehs

Localized depression ignored

North

Notes:1. hs,e,n,w: average level of finished ground2. Grade = lowest of hs,e,n,w

Arbitraryreferenceelevation

Artificially raising the surround-ing landscaping around the build-ing to decrease the building heightas defined by the building code is acontroversial practice (Figure 4.5).This may make the differencebetween permitting combustibleconstruction and requiring non-combustible construction for thebuilding.

Exceptions for Building Height

[3.2.1.1.(1)] The calculation ofbuilding height excludes rooftopenclosures that house elevatormachinery, air-conditioning andheating equipment and other ser-vices. Since these rooms are onlyaccessible to service personnel theyshould not constitute a danger foroccupants.

[3.2.2.14.(2)] The rooftop enclosure is not required to have a fire-resis-tance rating unless it exceeds onestorey, in which case it must meet

the requirements for the rest of thebuilding because its collapse couldhave repercussions for the top floorsof the building.

[3.2.1.1.(3)] A mezzanine is not considered as a storey in buildingheight if:

• its aggregate floor area is notmore than 40% of the area ofthe floor area below

• it is used in an open floor area

• with the exception of libraries,it has no visual obstructionabove or below it except for thefirst 1070mm above the floors(Figure 4.6)

Solid glazing typically seen in rinksor arena mezzanines is not consid-ered a visual obstruction. Limits tovisual obstructions ensure that occu-pants of the mezzanine are alertedto a life-threatening situation at thesame time as the occupants of thefloor area below.


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FIGURE 4.4

Determiningnumber ofstoreys

3

2

1 2

1

3

2

1

3

2

1

Building Area includes all 4 separated sections

Vertical fire separations60 min FRR

Building Height= 3 storeys

Building Height= 2 storeys


Building would be considered as a three storey building ifmezzanine not more than 40%of total floor area.

Building would be considered as a one storey building ifmezzanine not more than 10%of total floor area.

Visually unobstructed

< 1070mm

Visual obstruction

no partitions

no partitions

Visually unobstructed

< 1070mm

FIGURE 4.5

Artificiallyraised grade

FIGURE 4.6

Mezzaninesand buildingheights

[3.2.1.1.(4)] Small mezzanines, upto 10% of the floor area below, arenot considered as a storey in build-ing height even if there are visualobstructions above or below itexceeding 1070mm. In such a smallmezzanine, the number of occupantswill be limited and evacuationshould not be a problem.

Some authorities permit smallareas up to 10% of the area oflarger mezzanines to be enclosed,usually at the back of the mezza-nine. This allows small officeareas or washrooms on the mezza-nine which, by their size, do notsignificantly increase the firehazard and thereby do not war-rant adding an additional storeyto the building height.

[3.2.1.1.(5)] If there is more than one level of mezzanine, which ispartially or wholly superimposedabove another, the second and anyadditional mezzanines must becounted as a storey for determin-ing building height.

This ensures that where multiplemezzanines are used, they areincluded in the determination of

building height for fire safetyreasons (Figure 4.7). This appliesonly to mezzanines which are notalready included as storeys inbuilding height because of thearea or visual limitations. It isnot intended to apply to mezza-nines which are essentially at thesame level but separately locatedwithin the same storey.

Discretion must be used in apply-ing these rules for multiple mez-zanines and limits on enclosuresor visual obstructions. Obviously,the more complicated the buildingdesign the greater the fire risk.The critical issues are how quicklythe occupants will become awareof a fire and, once notified, howwell they can safely evacuate thearea.

[3.2.8.2.(1)] Most open mezzaninesare limited to 500m2 or less inarea except in Group A, Divisions1 and 3 major occupancies, notmore than two storeys in height.In most other cases, the mezza-nines must be enclosed by a vertical fire separation, whichautomatically makes the mezza-nine a storey for building height.


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First level not a storey in determining building height

Additional level is a storey in determining building height

FIGURE 4.7

Multiple levelsof mezzanine

[3.2.8.] If not enclosed, the floorarea containing the mezzanines isclassified as an interconnectedfloor space. Depending on the sizeof the opening, interconnected floorspaces are limited to certain typesof buildings. Additional fire protec-tion requirements are applied tooffset the hazard created by thelack of compartmentation (Chapter 5).

[3.2.1.1.(2)] Another exception tothe calculation of building heightis specific to arenas. The areasimmediately under tiers of seatsare not counted as a separatestorey if the space is used only for ancillary purposes such asrefreshment stands and dressingrooms. This is permitted because:

• these occupancies do not appre-ciably increase the hazard to lifesafety

• the interior is wide open• the occupants are always alert

and ready to evacuate

In many cases, if the arena wereclassified as two storeys in build-ing height, depending on its area,it could be required to be of non-combustible construction becauseof these incidental occupancies.

MAJOR OCCUPANCY

The objective of classifying build-ings and parts of buildings, asstated earlier, is to determine thelevel of protection required toensure the safety of the occupants


FIGURE 4.8

Office is a subsidiaryoccupancy tothe warehouse

given the risks associated withthe activities carried on in a specific area.

The use of a space, a group of rooms,a floor or an entire building for thesame purpose is referred to as anoccupancy.

Occupancy is defined as “the use orintended use of a building or partthereof for the shelter or supportof persons, animals or property.”

Each type of occupancy is subjectto requirements concerning:• structural fire endurance• flame spread• fire alarms• exiting• fire separation

It is also necessary to consider therelationship between various occu-pancies within a building becausesome constitute a greater fire andlife hazard to others. This is wherethe often misunderstood concept ofmajor occupancy is introduced.

Major occupancy is defined as: “theprincipal occupancy for which abuilding or part thereof is used orintended to be used and shall bedeemed to include the subsidiaryoccupancies which are an integralpart of the principal occupancy.”

The NBCC uses the concept ofmajor occupancy for two reasons:

• To ensure that the risks associ-ated with each occupancy areweighted against each other inthe context of the entire build-ing and not just the part of the

building under consideration.The most conservative set ofrequirements is used to designthe building.

• To avoid having to classify cer-tain uses within an occupancythat are deemed to be “sub-sidiary occupancies whichform an integral part of theprincipal occupancy.”

For example, a school may contain,in addition to classrooms, suchoccupancies as offices, a gymna-sium, an auditorium, a cafeteriaand laboratories. All of these usescould be considered as related tothe principal use of the building,which is education. In this casethe major occupancy would beGroup A, Division 2 and the dif-ferent activities are considered tobe part of that occupancy.

On the other hand, the audito-rium might be used regularly forperformances which are not neces-sarily associated with the normalactivities of the school, and couldbe treated as a distinct majoroccupancy.

The dividing line between whatconstitutes a major occupancyand a subsidiary occupancy willnot always be clear-cut; judge-ment must be exercised. It couldbe argued that shops within ahotel serve hotel guests andshould therefore be considered asubsidiary mercantile occupancy.However, such shops also serveother customers and could be considered a major occupancy intheir own right (Figure 4.9).


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[3.2.2.6.] Generally, the NBCCrequires that the entire building beconstructed according to the rulesof whichever major occupancy inthe building warrants the mostrestrictive requirements.

[3.2.2.7.(1)] However, since build-ings are usually designed so thateach storey is a separate com-partment, the NBCC states thatwhere one major occupancy isentirely above another, eachoccupancy shall be designed toits own respective requirements.Minimum fire-resistance ratingsfor the floor assemblies betweenthe storeys are specified.

The basic principle for determin-ing how a building must be constructed is:

• classify each area of a buildingaccording to its principal use(which then becomes the majoroccupancy for that part)

• determine the type of construc-tion and the necessary level ofprotection by considering thearea and height of the entirebuilding and the number ofstreets the building faces

This principle is illustrated byexamples in the following section.


FIGURE 4.9

Multiple occupancy

Rooms

Rooms, theatre andmeeting rooms

Lobby, rooms, shops, dining rooms and restaurant

Ground level

Major occupancy — Hotel (Group C)Subsidiary occupancies: Lobby (Group A-2)

Shops (Group E)Restaurant (Group A-2)Dining rooms (Group A-2)Theatre (Group A-1)Meeting rooms (Group A-2)

Rooms or Suites

GENERAL

Example 4.2Building height: six-storey Building area: 5000 m2

Major Occupancy: Group C, residential.

Construction and fire protectionrequirements — [3.2.2.43.]• automatic sprinklers• noncombustible construction• all floor assemblies must be

fire separations with a fire-resistance rating (FRR) of atleast one hour

• mezzanines must have a FRR ofat least one hour

• load bearing walls and columnsmust have a FRR of at least onehour

These minimum requirementsare intended to ensure that alloccupants have time to reach theexits and evacuate the building;in this case, at least one-hourfire-resistance for floors and sup-porting assemblies. The floorsare required to be constructed asfire separations to create firecompartments.

Example 4.3Now consider the introduction ofa number of shops (Group E) occu-pying most of the first storey ofthe building in Example 4.2. Construction and fire protectionrequirements — [3.2.2.57.]&[3.2.2.43.]• automatic sprinklers• noncombustible construction• floor assemblies over the base-

ment and first storey must befire separations with a FRR ofat least two hours

• for the other storeys, floor assem-blies must be fire separationswith a FRR of at least one hour

• mezzanines must have a FRR of at least one hour

• load bearing walls and columnsmust have a FRR at least equalto the supported structure

[3.2.2.7.] Even though an occu-pancy may be contained on a single storey, the level of fire pro-tection and type of constructionon that storey would impact thelevels of safety provided for otherfloors. Thus the occupancy ofgreatest risk is considered as ifoccupying the entire building sothat the minimum requirementswill provide sufficient egress, fire-fighting provisions and all othersafety factors commensurate withthat higher risk.

[3.2.2.5.] In this example, thestorey with shops will be treated asthough it were part of a six-storeycommercial building and the resi-dential portion treated as part of asix-storey residential building.

It must be kept in mind that thefire-safety objectives are to ensurethat occupants of the five upperfloors have sufficient time to bealerted to the danger and evacuatethe building, while permitting the fire department to undertakerescue and firefighting operations.An appropriate level of protectioncan only be achieved if the totalheight of the building is taken intoaccount for each major occupancy,that is, by considering each floor orgroup of floors containing a majoroccupancy as part of a building ofthe same height and occupancy.

Determining Construction Requirements 83

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4.3 Determining Construction Requirements

TABLE 4.2

Fire separationrequiredbetween majoroccupancies


Notes:

1. A 1-1/2 hour fire separation is required when the Group F, Division 3 occupancy is a storage garage ( [3.3.5.6.] ).

2. A 2 hour fire separation is required when the Group F, Division 2 occupancy is a repair garage ( [3.3.5.5.] ).

3. If the building containing a Group E major occupancy is not over three storeys

Fire Separation hours

Group A Division 1Assembly

Group A Division 2Assembly

1

1 Group A Division 3Assembly

1

1 11 Group A Division 4Assembly

1

2 2 2 Group B Division 1Care and Detention

2

2 2 2 2 Group B Division 2Care and Detention

2

1 1 1 1 2 Group CResidential

2

1 1 1 1 2 2 Group DBusiness and Personal Services

1

2 2 2 2 2 2 23 Group EMercantile

NR

NP NP NP NP NP NP NP 3 Group F Division 1Industrial

3

2 2 2 2 2 2 24 NR2 NR2 Group F Division 2Industrial

2

11 11 11 11 2 2 11 NR1 NR1 2 Group F Division 3Industrial

NR1

SEPARATION OF MAJOR OCCUPANCIES

But what about the floor separat-ing the storey of shops from thestorey of apartments?

[3.2.2.7.(2)] The requirements formultiple occupancy in the NBCCstate that when a major occupancyis entirely located above another,the floor assembly between themmust have the fire-resistance rating required for the lower occupancy.

[3.1.3.1.] The separation of majoroccupancies must also conform to the requirements of Table 4.2.This Table stipulates the mini-mum fire-resistance rating forfire separations between adjoin-ing major occupancies. The mostrestrictive requirement will govern.

In this example, the floor abovethe first storey containing theshops will be required to have afire-resistance rating of two hoursbased both on the FRR of twohours required for the mercantileoccupancy and the two hour sepa-ration required by Table 4.2.

In the case of a two-storey buildingcontaining mercantile shops onthe first storey and a restauranton the second storey, a two-hourfire separation between the firstand second storeys would berequired (Table 4.2). Requirementsbased on the lower occupancy, aGroup E occupancy in a two storeybuilding, would only require a fire-resistance of 45 minutes but themore restrictive requirement oftwo hours will govern.

This is consistent with theapproach to protect occupants infloors above from a more haz-ardous occupancy below.

Example 4.4 (Figure 4.10) Occupancies:

Storeys one and two: Storage Garage (Group F, Division 3)

Storey three: Mercantile Shops(Group E)

Storeys four to six: Offices (Group D)

Construction and fire protectionrequirements:• non-combustible construction• storeys one and two: one

hour FRR, sprinklers . . [3.2.2.75.]• storey three: two hour

FRR, sprinklers . . . . . . [3.2.2.57.]• storey four to six: one hour

FRR, no sprinklers . . . [3.2.2.50.]• roof assembly one hour

FRR . . . . . . . . . . . . . . . . . [3.2.2.50.]• separation F-3 and E:

1.5 hours FRR . . . . . . . . . [3.3.5.6.]• separation E and D:

not required . . . . . . . . . . [3.1.3.1.]

By applying the rules for multipleoccupancy buildings: • the floor assembly between the

first and second storeys has afire-resistance rating of one hour

• the floor assembly between thesecond and third storeys sepa-rates two major occupanciesand requires a 90 minute FRR( [3.3.5.6.] ) as the most restric-tive requirement governs

• the separation between the thirdstorey (Group E) and the topstoreys (Group D) is subject to


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the requirements for the loweroccupancy (two hours requiredfor Group E, up to six storeys)even though Table 4.2 does notrequire any fire-resistance rating between those majoroccupancies.

• the remaining top storeys musthave a FRR of one hour for theGroup D occupancy

• the top three storeys are notrequired to be sprinklered( [3.2.2.7.(1)] )

• the first two storeys (Group F,Division 3) and the thirdstorey (Group E) require sprin-kler protection

• the roof assembly must have aFRR of one hour since the entirebuilding is not sprinklered

Some adjoining major occupancies,such as D and E, do not haverequirements for fire separationin Table 4.2. This Table applies toboth vertical and horizontal sepa-rations and is not concerned withheight. A fire separation betweena shop and an office on the samefloor is not required. This isbecause the danger to occupants isminimized by the fact that occu-pants in the office portion arelikely fully alert and can respondrapidly to evacuate the fire floor.

FIGURE 4.10

Fire-resistancerating of supportingassemblies


1h columns

Group E,Major Occupancy

Group F, Division 3Major Occupancyopen air parking garage

Crawl space

2h columns

1.5h columns

1h columns

Ground level

Group D,Major Occupancy

Floor 1h

Floor 1.5h

Floor 2h

Floor 1h

Floor 1h

Roof 1h

This is not necessarily the casewhen the occupancies are super-imposed, because it may takelonger for the occupants to realizethe danger and travel distancesare increased. In this case the fireseparation requirements of thelower occupancy will govern.

[3.2.2.8.] If the total area of amajor occupancy in a particularGroup or Division is not morethan 10% of the floor area, it doesnot have to be considered as amajor occupancy for the purposesof Subsection 3.2.2.. This meansthat the construction require-ments do not have to be based onthis occupancy and that the occu-pancy separation requirements inTable 4.2 need not apply.

This is because it would proveoverly onerous in relation to therisks involved. This exception doesnot apply where the major occu-pancy is classified as Group F,Division 1 or 2, (Industrial, highor medium hazard), because of thesignificant inherent fire hazard.

FIRE-RESISTANCE RATING OF SUPPORTING ASSEMBLIES

[3.1.7.5.(1)] The NBCC requires in most cases that supportingassemblies for floors have a fire-resistance rating at least equal to that required for that floorassembly.

[3.2.2.7.(1)] However, it is not necessary to rate the supportingassemblies in a lower level occu-pancy on the basis of the fire protection requirements for theupper level.

The minimum fire performancerequired for the floor and its sup-porting assemblies depends on theexpected fire severity on that level.

In our example shown in Figure4.10, the columns supporting thefloor assembly above the Group Eoccupancies must have a fire-resistance of two hours on thatlevel only. The columns support-ing the floor above the parkinggarage on the second storey, even if they are supporting thecolumns above on the third storey,are only required to have a fire-resistance rating of 90 minutes.Similarly, the columns support-ing the floor assembly above thefirst storey are only required tohave a fire-resistance rating ofone hour.

[3.1.7.5.(2)] The same principleapplies to service rooms intended tocontain an occupancy considered tobe a high hazard. The fire-resistance rating for the serviceroom, required by Section 3.6, mightexceed the requirements for theremainder of the floor area.Although the construction enclos-ing these rooms must have a highfire-resistance rating, it does nothave to be supported by columns or walls having the same high fire-resistance. The high FRRrequirement is intended to containthe fire to the floor area or portionof the floor area where it is located.

CONSTRUCTION REQUIREMENT OPTIONS:

The construction requirements ofSubsection 3.2.2. are structured by: • occupancy


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• height and area• whether or not the building is

sprinklered • if not sprinklered, the number

of streets the building faces

The permitted maximum area of an unsprinklered building isinfluenced not only by its height,but also by the number of streetsthat a building faces. Generally,the area permitted when thebuilding faces one street isincreased by:• 25% if it faces two streets • 50% if it faces three streets

This accounts for the fact thatfirefighting is more effective ifthe fire department has directaccess to a building face. This isparticularly important to lifesafety. If a building faces morethan one street, firefighters havemore options in positioning truckladders and undertaking rescueoperations. Ensuring firefighters’access to a building is one of theimportant fire safety measureson which the NBCC is based(Chapter 9).

The 1995 NBCC no longer variespermitted areas of buildings withthe number of streets faced forsprinklered buildings. This is as aresult of a review of the require-ments for sprinklers and fire safetymeasures. This review concludedthat the level of safety of sprin-klered buildings should permit allsprinklered buildings to have themaximum area previously assignedto a sprinklered building facingthree streets, regardless of thenumber of streets faced.

[3.2.4.9.] To increase the relia-bility of automatic sprinklerinstallations, all sprinkler systems are required to be elec-trically supervised and have asignal automatically transmittedto the fire department.

For any given building, severalconstruction alternatives may beavailable and the designer maychoose the least restrictive.

Example 4.5Occupancy: office building

(Group D)Building Height: three storeysBuilding Area: 4000m2

Building Facing: two streets

Option A: Group D, up to 3 Storeys, Sprinklered [3.2.2.54]

In this case the building can be:• built entirely of wood-frame

construction having a 45-minutefire-resistance rating for majorassemblies except the roofassembly

• noncombustible constructionwith floors as fire separationsbut with no fire-resistance rating required

• heavy timber construction,except that roof deck and supports need not comply tominimum dimensions

• mixed construction incorporatingheavy timber and unprotectednoncombustible constructionalong with the 45-minute ratedwood-frame construction.


Option B: Group D, up to 6 Storeys [3.2.2.50]

In this case the building can be:• unsprinklered and• noncombustible construction

with a fire-resistance rating ofone hour for floors, roof andsupporting construction

Option C: Group D, Any Height,Any Area, Sprinklered [3.2.2.49.]

In this case, the building would berequired to be:• noncombustible construction

with a fire-resistance of twohours

Obviously, Option C would proba-bly not be considered unless therewere plans to enlarge the buildingin the near future, but the firsttwo options are viable. The owner

would have to weigh the costs andbenefits of providing:

a) the sprinkler system and com-bustible construction with 45-minute fire-resistance ratings or

b) providing noncombustible construction having one-hourfire-resistance rating.

The building could also be dividedby a firewall into two separatebuildings of equal area. Thiswould create another option.

Option D: Group D, up to 3 Storeys [3.2.2.53]

Building area: 2000m2 each

In this case, the buildings can be:• unsprinklered• same construction options as

Option A


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A complete review of the require-ments for automatic sprinklerprotection and other fire safetyprovisions was done for the 1995NBCC. This review looked at theloss statistics for sprinklered andunsprinklered buildings and thelevel of safety in these buildings.As a result of this study, the 1995NBCC makes sprinklers mandato-ry in the occupancies shown inTable 4.3

These requirements were based onthe high reliability and increasedlife safety provided by electricallysupervised sprinkler systems.During a fire, sprinklers systemscan:

• reduce fire temperatures• control a fire until the fire

department can take over fireextinguishing operations

• in some instances, extinguish afire entirely

CHANGES IN THE 1995 NBCC

The review also resulted in thereduction of certain fire safetyrequirements for sprinklered build-ings. A sprinklered building is nowonly required to face one street. Anautomatic sprinkler system willput the water directly on the fire,thus reducing the need for fire-fighters to have access to all sides ofthe building.Under the 1995 NBCC, a sprinkleredbuilding will have the height andarea allowances that were assignedto sprinklered buildings facingthree streets in the previous editionof the NBCC. This has resulted inan increase in allowed area of up to50% for many types of sprinkleredbuildings (Figure 4.12).For buildings permitted to be ofcombustible construction, someassembly, mercantile and indus-trial occupancies are permitted a

TABLE 4.3

Mandatorysprinklers inthe 1995 NBCC

Sprinkler Protection 91

4.4 Sprinkler Protection

Occupancy Group Division Sprinklers Required

Assembly Bldgs A 1 All

Assembly Bldgs A 2 All > 2 storeys or > 2400m2

Assembly Bldgs A 3 All > 2 storeys or > 6000m2

Assembly Bldgs A 4 All enclosed seating

Institutional (Detention) B 1 All

Institutional (Care) B 2 All

Residential C – All > 3 storeys

Business D – All > 6 storeys

Mercantile E – All > 3 storeys or > 1500m2

High Hazard Industrial F 1 All > 1 storey or 800m2

Med. Hazard Industrial F 2 All > 3 storeys or > 1500m2

Low Hazard Industrial F 3 All > 6 storeys

three- to five-fold increase in areawith sprinklers. In many othercases, building height may beincreased instead of building areaif sprinklers are provided.

Four-storey wood-frame construc-tion for residential, mercantileand commercial buildings (GroupsC, D and E) is now permitted.(Figure 4.11). Sprinkler protectionmust be provided along with onehour fire-resistance ratings (FRR)for all major assemblies, except forroof assemblies.

[3.2.4.7.] All sprinkler systemsare now required to be monitoredand electronically supervised. A supervised sprinkler system will

cause an alarm signal to be trans-mitted to the fire department, anindependent central station or pro-prietary control centre. An alarm issent when a sprinkler head is acti-vated or when a situation occursthat will affect the operation of thesystem, such as the movement of acontrol valve or loss of pressure.

In previous editions of the NBCC,the FRR of the roof was waived ifthe sprinkler system was elec-tronically supervised. The newrequirement for electronic super-vision of all automatic sprinklersystems has resulted in:

• fire-resistance ratings are nolonger required for the roof


Grade

45 minFRR

1990/1995 1990/1995

60 minFRR

Max. 2m

Notes:1. Group C Major Occupancy2. Buildings sprinklered (If residential sprinkler standard NFPA 13R is applied sprinklers are not required in attic space. See Section 9)3. Building assumed to face one street4. Maximum building area per floor is 1800m2

FIGURE 4.11

Four-storeywood-frameconstruction

assemblies in sprinkleredbuildings

• heavy timber roofs are now permitted in all sprinklerednoncombustible buildings ofany area, up to two storeys inheight [3.2.2.16]

Since a roof assembly does notrequire a rating, the supports donot have to be rated either. Thisresults in greater design flexibility.As well, it removes the requirementfor minimum sizes of heavy timberstructural components and decks in buildings permitted to be of com-bustible construction.

Example 4.6

Determine the maximum area ofthe following:Occupancy: restaurant (Group A,

Division 2)Building Height: one storey plus

basement

Building Construction: unratedwood-frame construction

Facing: one street• unsprinklered — maximum

area = 400m2 ( [3.2.2.28] )• sprinklered — maximum

area = 1200m2 ( [3.2.2.27] )

Example 4.7

Determine the maximum heightof the following:Occupancy: mercantile ( Group D)Building Construction: wood-

frame with 45 minute FRRFacing: one streetBuilding Area: 1500m2

• unsprinklered — maximumheight = 1 storey ( [3.2.2.59] )

• sprinklered — maximumheight = 3 storeys ( [3.2.2.60] )

FIGURE 4.12

Impact ofsprinklerchanges:increased area

Impact ofsprinklerchanges:increasedheight

Sprinkler Protection 93

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1990 NBCC 1995 NBCC

No FRR800 M2

3/4H FRR3200 M2

No FRR1200 M2

3/4H FRR4800 M2

Group A, Div. 2; Facing 1 Street; Sprinklered

1990 NBCC 1995 NBCC

Group C; Facing 1 Street; 1800m2; Sprinklered

The NBCC has specific require-ments for underground storeys.Firefighting in basements is verydifficult because:

• access and venting are complicated by the scarcity of openings to the outside

• firefighters must enter base-ments from the top, that is,through the hottest air layer

• firefighters are usually facedwith heavy smoke conditions

[3.2.1.5.(1)] For these reasons, theNBCC requires that basements be:

• sprinklered or

• in unsprinklered buildings,divided into compartments600m2 or less by fire separationswith the same fire-resistancerating as that required for thefloor above

[3.2.2.15.(2)] Underground con-struction extending more than onestorey below ground level musthave all levels sprinklered. Floorsand their supporting assembliesmust have a fire-resistance ratingof either two or three hours,depending on the occupancy.

[3.2.2.15.(3)] An exception to therequirements for sprinklers in basements applies when the storeyimmediately below the first storeycontains only residential occupan-cies and the building is not other-wise required to be sprinklered. Inthis case, sprinklers are notrequired in that storey providedthere are unobstructed access

openings for each 15m of walllength. This exception allows base-ment apartments commonly foundin residential buildings whichcontain parking garage areas onlower sub-grade levels.

[3.2.1.2.] The NBCC also allows abasement used primarily as a park-ing garage to be considered as aseparate building for the purposeof applying fire protection require-ments, if:

• the garage is separated fromthe rest of the building by aconcrete fire separation havinga fire-resistance rating of twohours

• the portion of the basementwalls extending above groundlevel also has a fire-resistancerating of two hours

This allows buildings that may be separated by firewalls or clearspace to be treated as separatebuildings in calculating buildingarea even if there is a large underground parking garageunderneath. In this way, the con-struction requirements of theabove ground buildings will notbe affected by the area of theparking garage. The above groundportions can often be separated topermit wood frame construction.

Crawl spaces usually have a morelimited use than basementsbecause of their size. Requirementsfor crawl spaces are therefore morelenient because they are assumednot to present a fire hazard.

Storeys Below Ground 95

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4.5 Storeys Below Ground

[3.2.2.9.(1)] A crawl space is considered a basement if it is:

• more then 1.8m high

• used for any occupancy

• used for passage of flue pipes, or

• used as a plenum in com-bustible construction

In these instances, the require-ments for basements, as outlinedabove, would apply.

[3.1.11.6.(1).] Unsprinklered crawlspaces not classified as basementsmust be divided by firestopping incompartments of not more than600m2 with no dimension greaterthan 30m.


Chapter SummaryThis Chapter has explained the classification of buildingsand parts of buildings, how building size is calculated andhow construction requirements are determined. It has alsodescribed the use of fire separations to achieve compartmen-tation within and between major occupancies, and some specific requirements relating to basements and roofs.

Building classification is also relevant to requirements forstructural fire protection, flame-spread limitations, firedetection and alarms, exits and safety, as described inChapters 5 through 9.

USE OF DESIGN REQUIREMENT TABLES

The fire protection requirementsin Subsection 3.2.2. of the NBCCare summarized in the DesignRequirement Tables at the end of this Chapter.

Each Table covers a major occu-pancy group (�) and lists examplesof occupancies included within thegroup (�). Each column representsthe construction requirements asstated in the referenced NBCCArticles (�) that pertain to themajor occupancy and buildingheight. As mentioned above, morethan one Article can apply to a particular situation: the leastrestrictive is permitted to be used.

The tables are particularly usefulbecause each construction require-ment is identified by a symbol (�)which indicates one of the fourconstruction types permitted asfollows:

1 Noncombustible construction

2 Heavy timber construction,noncombustible constructionor a combination

3 Wood-frame construction with required fire perfor-mance characteristics, heavytimber construction, noncom-bustible construction or anycombination

4 Wood-frame construction orany other building systemwithout special fire perfor-mance characteristics

Design Requirement Tables 97

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Design Requirement Tables

Group DDBusinessand PersonalServices

Banks, BarberShops, Officesand RadioStations

MAXIMUM BUILDING HEIGHT, STOREYS 1 2 1 2 3

MAXIMUM Unsprinklered [3.2.2.55.] [3.2.2.53.]BUILDING AREA facing 1 street 1000 800 4800 2400 1600m

2facing 2 streets 1250 1000 6000 3000 2000facing 3 streets 1500 1200 7200 3600 2400

Sprinklered [3.2.2.56.] [3.2.2.54.]3000 2400 14400 7200 4800

CONSTRUCTION Basements 3 Subdivided by 45-minute 3 Subdivided by 45-minute REQUIREMENTS fire separations into areas not fire separations into areas not

exceeding 600m2, unless exceeding 600m2, unless

sprinklered. sprinklered.

Loadbearing Walls, 3 Loadbearing elements 3 Loadbearing elementsColumns, Beams, supporting assemblies required to supporting assemblies required toArches have a fire-resistance rating must have a fire-resistance rating must

have a 45-minute fire-resistance have a 45-minute fire-resistancerating or be of unrated noncom- rating or be of unrated noncom-bustible or combination except that bustible or combination except thatfire separation floor over basements fire separation floor over basementsmust be supported by a 45-minute must be supported by a 45-minuterated assembly. rated assembly.

CONSTRUCTION TYPES IN TABLES

1 Noncombustible construction

The building must be constructedof noncombustible materialsexcept as permitted in NBCCSubsection 3.1.5.

Use of wood is limited but not prohibited in noncombustible construction. The following wooduse is allowed: • wood nailing elements on non-

combustible backing to attachwall and ceiling finishes

• wood millwork such as trim,windows, doors and framesallowed

• wood nailing strips or membersup to 300 mm high as finishedfloor support

• wood stage flooring if sup-ported by noncombustible construction

• wood flooring; • wood framing and solid lum-

ber partitions under specificconditions

• lumber and plywood wall panelling

• FRT plywood and lumber ceilings

• wood studs and FRT plywoodin nonloadbearing exteriorwall sections

• heavy timber roof assembly forbuildings up to 2 storeys inheight

2 Heavy timber construction,noncombustible construction or a combination

The building can be constructedusing noncombustible materialswith the same exceptions as theprevious category or heavy timberconstruction sized to meet 45-minute fire-resistance rating.

The following construction is permitted:• floor decks can be tongue and

groove plank, splined plank orspiked plank on edges

• roof decks can be tongue andgroove plywood or plank,splined plank or laminatedplank on edges

• columns, beams, arches andtrusses can be lumber or glue-laminated timber

3 Wood-frame construction withrequired fire performance charac-teristics, heavy timber construction,noncombustible construction orany combination

The building can be: • wood-frame construction with a

required fire-resistance rating or • heavy timber construction or• noncombustible construction

4 Wood-frame construction or anyother building system without specialfire performance characteristics

Any building material can beused in this category and no fireperformance characteristics arerequired.



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1 Noncombustible construction. 3 Wood-frame construction with required fire performance characteristics,heavy timber construction, noncombustible construction or any combination.

2 Heavy timber construction, noncom- 4 Wood-frame construction or any other building system without bustible construction or a combination. special fire performance characteristics.

DESIGN REQUIREMENT TABLES

A1Assembly

Theatres,TelevisionStudios andOpera Houses

Group A — Division 1

MAXIMUM BUILDING HEIGHT, STOREYS Unlimited

MAXIMUM Sprinklered [3.2.2.20.]BUILDING AREA Unlimited.m2

CONSTRUCTIONREQUIREMENTS Basements 1 Noncombustible construction.

Floor Assemblies Above 1 2-hour fire separation.Basements

Floor Assemblies Above 1 Noncombustible construction.Crawl Spaces

All Other Floor Assemblies 1 2-hour fire separation.

Mezzanines 1 1-hour fire-resistance rating.5

Roof Assemblies 2 Heavy timber in buildings up to two storeys or noncombustible construction. 6

Loadbearing Walls, 1 Fire-resistance rating must Columns, Beams, Arches equal that required for supported

assembly. 6





A1Assembly

Theatres,TelevisionStudios andOpera Houses

Group A — Division 1continued

MAXIMUM BUILDING HEIGHT, STOREYS 1 1

MAXIMUM Sprinklered [3.2.2.21.] [3.2.2.22.]BUILDING AREA 600 Unlimited.m2

USE AND Occupant load of building not Occupant load of auditorium floorOCCUPANCY more than 600 persons. 2,4 area not more than 300 persons. 2,3

RESTRICTION

CONSTRUCTION Basements 2 Heavy timber or noncom- 4 No special requirements. REQUIREMENTS bustible construction or a

combination.

Floor Assemblies Above 2 Heavy timber or 45-minute 3 45-minute fire separation.Basements noncombustible fire separation.

Floor Assemblies Above 2 Heavy timber or noncom- 4 No special requirements.Crawl Spaces bustible construction or a

combination.

All Other Floor Assemblies 2 Heavy timber or 45-minute 3 45-minute fire separation.1

noncombustible fire separation.1

Mezzanines 2 Heavy timber or noncom- 3 45-minute fire-resistance bustible construction or a rating if of combustible construction.combination.

Roof Assemblies 2 Heavy timber or noncom- 4 No special requirements.bustible construction or a combination.

Loadbearing Walls, 2 Heavy timber or noncom- 3 45-minute fire-resistance Columns, Beams, Arches bustible construction with a rating, or unrated non-combustible

fire-resistance rating, not less or a combination thereof if than that required for the supported assembly required tosupported assembly. have a fire-resistance rating, except

that rated floor separations must besupported by a 45-minute rated assembly.


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Group A — Division 2 A2Assembly

Auditoria,Churches andNonresidentialSchools

MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 6

MAXIMUM Sprinklered [3.2.2.23.] [3.2.2.24.]BUILDING AREA Unlimited. Unlimited.m2

CONSTRUCTIONREQUIREMENTS Basements 1 Noncombustible construction. 1 Noncombustible construction.

Floor Assemblies Above 1 2-hour fire separation. 1 1-hour fire separation.Basements

Floor Assemblies Above 1 Noncombustible construction. 1 Noncombustible construction.Crawl Spaces

All Other Floor Assemblies 1 2-hour fire separation. 1 1-hour fire separation.

Mezzanines 1 1-hour fire-resistance rating.5 1 1-hour fire-resistance rating.5

Roof Assemblies 2 Heavy timber in buildings 2 Heavy timber in buildingsup to two storeys or noncombustible up to two storeys or noncombustibleconstruction. 6 construction. 6

Loadbearing Walls, 1 Fire-resistance rating must 1 Fire-resistance rating must Columns, Beams, Arches equal that required for supported equal that required for supported

assembly. 6 assembly. 6






A2Assembly



MAXIMUM Unsprinklered [3.2.2.25.]BUILDING AREA facing 1 street 1600 800m2 facing 2 streets 2000 1000

facing 3 streets 2400 1200

Sprinklered [3.2.2.26.]4800 2400

CONSTRUCTION Basements 3 Subdivided by 45-minute fire separations into areasREQUIREMENTS not exceeding 600m2, unless sprinklered.

Floor Assemblies Above 3 45-minute fire separation.Basements

Floor Assemblies Above 4 No special requirements.Crawl Spaces

All Other Floor Assemblies 3 45-minute fire separation if of combustible construction;unrated fire separation if of noncombustible construction.1

Mezzanines 3 45-minute fire-resistance rating if of combustibleconstruction or unrated noncombustible5

Roof Assemblies 3 45-minute fire-resistance rating if of combustible construction, waived for a 1-storey building with FRTWroof system if building area is not more than one-halfvalues otherwise permitted; or unrated noncombustibleconstruction.7 No rating requirements if sprinklered.

Loadbearing Walls, 3 45-minute fire-resistance rating or unrated noncom-Columns, Beams, Arches bustible or a combination thereof if supported assembly

required to have a fire-resistance rating, except that a fireseparation floor over basements must be supported by45-minute rated assembly.


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A2Assembly



MAXIMUM Unsprinklered [3.2.2.28] 9

BUILDING AREA facing 1 street 400 Not Permitted.m2 facing 2 streets 500

facing 3 streets 600

Sprinklered [3.2.2.27.]1200 with basement. 6002400 without basement.

CONSTRUCTIONREQUIREMENTS Basements 4 No special requirements.



All Other Floor Assemblies 4 No special requirements.1

Mezzanines 4 No special requirements.5

Roof Assemblies 4 No special requirements.

Loadbearing Walls, 3 Fire-resistance rating must equal that required for supported Columns, Beams, Arches assembly (only applies to floors over basements).


MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 1 2

MAXIMUM Unsprinklered [3.2.2.30.]BUILDING AREA facing 1 street Not permitted. 4000 2000m2 facing 2 streets 5000 2500


Sprinklered [3.2.2.29.] [3.2.2.31.]Unlimited. 12 000 6000

CONSTRUCTION Basements 1 Noncombustible construction. 1 Subdivided by 1-hour fire REQUIREMENTS separations into areas not

exceeding 600m2, unless sprinklered.



All Other Floor Assemblies 1 2-hour fire separation. 1 1-hour fire separation.1


Roof Assemblies 2 Heavy timber in buildings up 2 45-minute fire-resistance rating,to two storeys, or noncombustible waived for heavy timber. No ratingconstruction. 6 or other special requirements if

sprinklered. 6, 7

Loadbearing Walls, 1 Fire-resistance rating must 2 Fire-resistance rating mustColumns, Beams, Arches equal that required for supported equal that required for supported

assembly. 6 assembly, heavy timber structuralmembers permitted within storeyimmediately below roof assembly.





A3Assembly

Arenas, Rinksand IndoorSwimmingPools


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A3Assembly

Arenas, Rinksand IndoorSwimmingPools



MAXIMUM Unsprinklered [3.2.2.32] [3.2.2.34.]BUILDING AREA facing 1 street 2400 1000m2 facing 2 streets 3000 1250


Sprinklered [3.2.2.33]Not applicable. 7200

CONSTRUCTION Basements 3 Subdivided by 45-minute 3 Subdivided by 45-minute REQUIREMENTS fire separations into areas fire separations into areas

not exceeding 600m2. not exceeding 600m2 unlesssprinklered.

Floor Assemblies Above 3 45-minute fire separation. 3 45-minute fire separation.Basements

Floor Assemblies Above 4 No special requirements. 4 No special requirements.Crawl Spaces

All Other Floor Assemblies 4 No special requirements.1 4 No special requirements.1

Mezzanines 3 45-minute fire-resistance 4 No special requirements.5

rating if of combustible construc-tion, or unrated noncombustible construction.5

Roof Assemblies 3 45-minute fire-resistance 4 No special requirements.rating if of combustible construc-tion, waived if building area is not more than one-half values otherwise permitted and FRTW roof system used, or unrated noncombustible construction.7

Loadbearing Walls, 3 45-minute fire-resistance rating 3 Fire separation floor over Columns, Beams, Arches or unrated noncombustible or a basement must be supported by a

combination thereof if supported 45-minute rated assembly.assembly required to have a fire-resistance rating, except that a fire separation floor over basementsmust be supported by a 45-minute rated assembly.






A4Assembly

Bleachers,Grandstandsand Stadia

MAXIMUM BUILDING HEIGHT, STOREYS Not regulated

MAXIMUM Unsprinklered [3.2.2.35.(3)] [3.2.2.35]BUILDING AREA or Sprinklered10 Occupant load less than 1500 Unlimited.m2 persons; structure has limiting

distance of at least 6m.

CONSTRUCTIONREQUIREMENTS Basements Not applicable. Not applicable.

Floor Assemblies Above Not applicable. Not applicable.Basements

Floor Assemblies Above Not applicable. Not applicable.Crawl Spaces

All Other Floor Assemblies 4 No special requirements. 1 Noncombustible construction.

Mezzanines Not applicable. Not applicable.

Roof Assemblies 4 No special requirements. 2 Heavy timber or unratednoncombustible construction.

Loadbearing Walls, 4 No special requirements. 2 Noncombustible construction; Columns, Beams, Arches heavy timber roof assembly may

be supported by heavy timberstructural members.

Notes for Group A Occupancies:1 The other floor assemblies in a 1 storey building refers to a sloped floor or a seating area ascending from the main floor

in an assembly building.2 No occupancy allowed above or below auditorium other than one serving or depending on it (e.g. washrooms and theatre office).3 No part of auditorium floor can be more than 5m above or below grade.4 Up to 40% of building area permitted as two storeys if used for such things as dressing rooms, theatre offices

and washrooms.5 Exterior balconies shall be constructed in accordance with the type of construction required and if these balconies form

part of the means of egress then they are required to have a fire-resistance rating equal to that for mezzanines. 6 A roof assembly of heavy timber construction is permitted for sprinklered buildings of any area, up to 2 storeys in height.

(Structural members in the storey immediately below the roof assembly can be heavy timber construction.)7 Fire-resistance rating waived for roof assembly having at least 6m clearance above main floor in gymnasia and

Group A, Division 3 occupancies.8 Wood studs and FRT plywood are permitted in non-loadbearing exterior wall assemblies in unsprinklered buildings

3 storeys or less in building height and in sprinklered buildings of unlimited height.9 Maximum building areas can be doubled if no basement and 1-hour fire separation divides building into two areas,

with neither area exceeding values given.10 Sprinklers shall be installed in all spaces below tiers of seats if those spaces are used for occupancy.


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Group B — Division 1


B1Care orDetention

Jails, Police Stations 2

and PsychiatricHospitals, all withDetention Quarters

MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 1 2 3

MAXIMUM Sprinklered [3.2.2.36.] 6 [3.2.2.37.] 6

BUILDING AREA Unlimited. Unlimited. 12 000 8000m2






Roof Assemblies 2 Heavy timber in buildings up 2 Heavy timber in buildings up to two storeys or noncombustible to two storeys or noncombustibleconstruction.4 construction.4

Loadbearing Walls, 1 Fire-resistance rating must 1 Fire-resistance rating must Columns, Beams, Arches equal that required for the equal that required for the

supported assembly.4 supported assembly.4

Group B — Division 2

MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 1 2 3

MAXIMUM Sprinklered [3.2.2.38.] [3.2.2.39.]BUILDING AREA Unlimited. Unlimited. 12 000 8000 m2






Roof Assemblies 2 Heavy timber in buildings up 2 Heavy timber in buildings upto two storeys or noncombustible to two storeys or noncombustibleconstruction.4 construction.4


supported assembly.4 supported assembly.4





B2Care orDetention

Infirmaries, Orphanages, Hospitals,Police Stations3 with DetentionQuarters and Psychiatric Hospitalswithout Detention Quarters


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B2Care orDetention

Infirmaries, Orphanages,Hospitals, Police Stations3

with Detention Quartersand Psychiatric Hospitalswithout Detention Quarters

Group B — Division 2continued

MAXIMUM BUILDING HEIGHT, STOREYS 1 2 1

MAXIMUM Sprinklered [3.2.2.40] [3.2.2.41.]BUILDING AREA 2400 1600 500m2

CONSTRUCTIONREQUIREMENTS Basements 4 No special requirements. 4 No special requirements.



All Other Floor Assemblies 3 45-minute fire separation. 4 Not applicable.

Mezzanines 3 45-minute fire-resistance 4 No special requirements.rating if of combustible construc-tion or unrated noncombustible construction.1

Roof Assemblies 4 No special requirements. 4 No special requirements.


supported assembly. supported assembly.

Notes for Group B Occupancies:

1 Exterior balconies shall be constructed in accordance with the type of construction required and if these balconiesform part of the means of egress then they are required to have a fire-resistance rating equal to that for mezzanines.

2 Exceeding 1 storey in building height or 600m2 in building area.

3 Not exceeding 1 storey in building height and 600m2 in building area.

4 Roof assemblies of heavy timber construction permitted for sprinklered buildings of any area up to 2 storeys in height.(Structural members in the storey immediately below the roof assembly can be heavy timber construction.)

5 Wood studs and FRT plywood are permitted in non-loadbearing exterior wall assemblies in sprinklered buildings ofany height.

6 A building containing an impeded egress zone need not conform to the specified requirements provided the building and occupancy is in accordance with the requirements of Article [3.2.2.19] and the appropriate Article inSubsection 3.2.2.





CResidential

Apartments,BoardingHouses andMotels

Group C

MAXIMUM BUILDING HEIGHT, STOREYS Unlimited

MAXIMUM Sprinklered [3.2.2.42.]BUILDING AREA Unlimited.m2


Floor Assemblies Above 1 2-hour fire separation.2

Basements


All Other Floor Assemblies 1 2-hour fire separation.2


Roof Assemblies 2 Heavy timber in buildings up to two storeys or noncombustible construction.5

Loadbearing Walls, 1 Fire-resistance rating must equal that required for theColumns, Beams, Arches supported assembly. 5

Group Ccontinued

MAXIMUM BUILDING HEIGHT, STOREYS 1 2 3 4 5 6

MAXIMUM Unsprinklered [3.2.2.44.]BUILDING AREA facing 1 street Unlimited. 6000 4000 Not permitted.m2 facing 2 streets Unlimited. Unlimited. 5000 Not permitted.

facing 3 streets Unlimited. Unlimited. 6000 Not permitted.

Sprinklered [3.2.2.43.]Unlimited. Unlimited. 12 000 9000 7200 6000

CONSTRUCTION Basements 1 Subdivided by 1-hour fire separations into areas not exceeding REQUIREMENTS 600m2, unless sprinklered.


Basements




Roof Assemblies 2 1-hour fire-resistance rating unless sprinklered.4,5

Loadbearing Walls, 1 Fire-resistance rating must equal that required for Columns, Beams, Arches supported assembly. 5


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CResidential




Group Ccontinued

MAXIMUM BUILDING HEIGHT, STOREYS 1 2 3 4

MAXIMUM Sprinklered [3.2.2.45.] 7

BUILDING AREA 7200 3600 2400 1800m2



Basements



Mezzanines 3 1-hour fire-resistance rating.1,3


Loadbearing Walls, 3 Fire-resistance rating must equal that required for Columns, Beams, Arches supported assembly.





CResidential



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CResidential


Group Ccontinued


MAXIMUM Unsprinklered [3.2.2.46.]7

[3.2.2.47.]BUILDING AREA facing 1 street 2400 1200 800 1800 900 600m2 facing 2 streets 3000 1500 1000 2250 1125 750

facing 3 streets 3600 1800 1200 2700 1350 900

Sprinklered [3.2.2.48.]Not applicable. 5400 2700 1800

CONSTRUCTION Basements 3 Subdivided by 1-hour fire 3 Subdivided by 45-minute REQUIREMENTS separations into areas not fire separations into areas not

exceeding 600m2. exceeding 600m2, unlesssprinklered.

Floor Assemblies Above 3 1-hour fire separation.1 3 45-minute fire separation.1Basements


All Other Floor Assemblies 3 1-hour fire separation.1 3 45-minute fire separation.1

Mezzanines 3 1-hour fire-resistance rating.1,3 3 45-minute fire-resistance rating, if of combustible construction.1,3

Roof Assemblies 3 1-hour fire-resistance rating. 4 No special requirements.

Loadbearing Walls, 3 Fire-resistance rating must 3 Fire-resistance rating mustColumns, Beams, Arches equal that required for the equal that required for the

supported assembly. supported assembly.

Notes for Group C Occupancies:1 When building contains dwelling units exceeding 1 storey (and the provisions of Sentence [3.3.4.2.(3)] of the NBCC

are complied with) floor assemblies within dwelling units do not have to be built as fire separations; if there is nodwelling unit above another, the fire-resistance rating requirement for such floors within the dwelling units is waived.

2 When building contains dwelling units exceeding 1 storey (and the provisions of Sentence [3.3.4.2.(3)] of the NBCC arecomplied with) floor assemblies within dwelling units do not have to be built as fire separations, and only 1-hour fire-resistance rating required.


4 Waived for sprinklered buildings.5 Roof assemblies of heavy timber construction permitted for sprinklered buildings up to 2 storeys. (Structural members in

the storey immediately below the roof assembly can be heavy timber construction.)6 Wood studs and FRT plywood are permitted in non-loadbearing exterior wall assemblies in unsprinklered buildings

3 storeys or less in building height and in sprinklered buildings of unlimited height.7 Heavy timber components or assemblies must provide minimum 1 hour fire-resistance rating.





DBusinessand PersonalServices


Group D

MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 1 2 3 4 5 6

MAXIMUM Unsprinklered [3.2.2.50.]BUILDING AREA facing 1 street Not permitted. Unlimited. 7200 4800 3600 2880 2400m2 facing 2 streets Unlimited. Unlimited. 6000 4500 3600 3000

facing 3 streets Unlimited. Unlimited. 7200 5400 4320 3600

Sprinklered [3.2.2.49.] [3.2.2.51.]Unlimited. Unlimited. Unlimited. 14 400 10 800 8640 7200

CONSTRUCTION Basements 1 Noncombustible 1 Subdivided by 1-hour fire separations intoREQUIREMENTS construction. areas not exceeding 600m2, unless sprinklered.

Floor Assemblies Above 1 2-hour fire 1 1-hour fire separation. Basements separation.

Floor Assemblies Above 1 Noncombustible 1 Noncombustible construction.Crawl Spaces construction.

All Other Floor Assemblies 1 2-hour fire 1 1-hour fire separation.separation.

Mezzanines 1 1-hour fire- 1 1-hour fire-resistance rating.1

resistance rating.1

Roof Assemblies 2 Heavy timber 2 1-hour fire-resistance rating, waived for in buildings up to 1 storey buildings and for sprinklered buildings.2

two storeys or noncombustible construction. 2

Loadbearing Walls, 1 Fire-resistance 1 Fire-resistance rating must equal that requiredColumns, Beams, Arches rating must equal for the supported assembly. 2

that required for the supportedassembly. 2


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Group Dcontinued




MAXIMUM BUILDING HEIGHT, STOREYS 1 2 3 4

MAXIMUM Unsprinklered Not applicable.BUILDING AREAm2 Sprinklered [3.2.2.52.]

3

3600 3600 3600 3600


Floor Assemblies Above 3 1-hour fire separation.Basements


All Other Floor Assemblies 3 1-hour fire separation.



Loadbearing Walls, 3 Fire-resistance rating must equal that required for Columns, Beams, Arches supported assembly.

Notes for Group D Occupancies:


2 Roof assemblies of heavy timber permitted for sprinklered buildings up to 2 storeys, of any area. (Structural membersin the storey immediately below the roof assembly can be heavy timber construction.)

3 Heavy timber components or assemblies must provide at least 1-hour fire-resistance rating.

4 Wood studs and FRT plywood are permitted in non-loadbearing exterior wall assemblies in unsprinklered buildings 3 storeys or less in building height and in sprinklered buildings of unlimited height.







Group Dcontinued


MAXIMUM Unsprinklered [3.2.2.53.] [3.2.2.55.]BUILDING AREA facing 1 street 4800 2400 1600 1000 800m2 facing 2 streets 6000 3000 2000 1250 1000

facing 3 streets 7200 3600 2400 1500 1200

Sprinklered [3.2.2.54.] [3.2.2.56.]14 400 7200 4800 3000 2400

CONSTRUCTION Basements 3 Subdivided by 45-minute 3 Subdivided by 45-minute REQUIREMENTS fire separations into areas not fire separations into areas not

exceeding 600m2, unless exceeding 600m2, unlesssprinklered. sprinklered.



All Other Floor Assemblies 3 Must be fire separation; 3 Must be fire separation;45-minute fire-resistance rating 45-minute fire-resistance ratingrequired if of combustible required if of combustibleconstruction. construction.

Mezzanines 3 45-minute fire-resistance 4 No special requirements.rating if of combustible construction.1

Roof Assemblies 3 45-minute fire-resistance 4 No special requirements.rating if of combustible construc-tion, waived for sprinkleredbuildings and 1-storey buildings with FRTW roof systems if buildingarea is not more than one-half values otherwise permitted, or unrated noncombustible.

Loadbearing Walls, 3 Loadbearing elements 3 Loadbearing elementsColumns, Beams, Arches supporting assemblies required to supporting assemblies required to

have a fire-resistance rating must have a fire-resistance rating musthave a 45-minute fire-resistance have a 45-minute fire-resistance rating or be of unrated noncom- rating or be of unrated noncom-bustible or combination except that bustible or combination except thatfire separation floor over basements fire separation floor over basementsmust be supported by a 45-minute must be supported by a 45-minuterated assembly. rated assembly.


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EMercantile

DepartmentStores, ExhibitionHalls andSupermarkets

Group E

MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 1 2 3 4

MAXIMUM Sprinklered [3.2.2.57.] [3.2.2.58.]3

BUILDING AREA Unlimited. 1800 1800 1800 1800m2

CONSTRUCTION Basements 1 Noncombustible 4 No special requirements.REQUIREMENTS construction.


Floor Assemblies Above 1 Noncombustible 4 No special requirements.Crawl Spaces construction.



resistance rating.1

Roof Assemblies 2 Heavy timber in 4 No special requirements.buildings up to two storeys or noncom-bustible construction.2

Loadbearing Walls, 1 Fire-resistance 3 Fire-resistance rating must equal that Columns, Beams, Arches rating must equal that required for supported assembly.

required for supported assembly.

2





EMercantile

DepartmentStores, ExhibitionHalls andSupermarkets

Notes for Group E Occupancies:



3 Heavy timber components or assemblies must provide at least 1-hour fire-resistance rating.


Group Econtinued


MAXIMUM Unsprinklered [3.2.2.59.] [3.2.2.61.]BUILDING AREA facing 1 street 1500 1200 800 1000 600m2 facing 2 streets 1500 1500 1000 1250 750

facing 3 streets 1500 1500 1500 1500 900

Sprinklered [3.2.2.60.] [3.2.2.62.]7200 3600 2400 3000 1800

CONSTRUCTION Basements 3 Subdivided by 45-minute fire 3 Subdivided by 45-minute fire REQUIREMENTS separations into areas not exceeding separations into areas not exceeding

600m2, unless sprinklered. 600m2, unless sprinklered.



All Other Floor Assemblies 3 45-minute fire separation. 3 45-minute fire separation.

Mezzanines 3 45-minute fire-resistance rating 4 No special requirements.if of combustible construction.1

Roof Assemblies 3 45-minute fire-resistance rating, 4 No special requirements. waived for 1-storey buildings with unrated noncombustible roof systems,for 1-storey buildings with FRTW roofsystems and for sprinklered buildings.

Loadbearing Walls, 3 45-minute fire-resistance rating 3 Fire-resistance rating must Columns, Beams, Arches or unrated noncombustible or a com- equal that required for supported

bination thereof if supported assembly assembly.required to have a fire-resistance rating, except that fire separation floorover basements and other fire sep-aration floors must be supported by assembly of at least equivalent rating.


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F1Industrial

Distilleries,Flour Mills, andSpray PaintingOperations

Group F — Division 1

MAXIMUM BUILDING HEIGHT, STOREYS 1 2 3 4 1 2 3

MAXIMUM Sprinklered [3.2.2.63.] [3.2.2.64.]BUILDING AREA 9000 4500 3000 2250 3600 1800 1200m2

CONSTRUCTION Basements 1 Noncombustible construction. 2 Heavy timber or non-REQUIREMENTS combustible construction.

Floor Assemblies Above 1 2-hour fire separation. 2 Heavy timber or 45-minuteBasements noncombustible fire separation.

Floor Assemblies Above 1 Noncombustible construction. 2 Heavy timber or non-Crawl Spaces combustible construction.

All Other Floor Assemblies 1 2-hour fire separation. 2 Heavy timber or 45-minutenoncombustible fire separation.

Mezzanines 1 1-hour fire-resistance rating.2 2 Heavy timber or non-combustible construction.2

Roof Assemblies 2 Heavy timber in buildings up 2 Heavy timber or non-to two storeys or noncombustible combustible construction.construction. 3

Loadbearing Walls, 1 Fire-resistance rating must equal 2 Fire-resistance ratingColumns, Beams, Arches that required for supported assembly. 3 must equal that required for

supported assembly.





F1Industrial

Distilleries,Flour Mills, andSpray PaintingOperations

Group F — Division 1continued

MAXIMUM BUILDING HEIGHT, STOREYS 1 2 1

MAXIMUM Unsprinklered Not permitted. [3.2.2.66.]BUILDING AREA 800 m2

Sprinklered [3.2.2.65.] Not applicable.2400 1200

CONSTRUCTION Basements 4 No special requirements. 3 Subdivided by 45-minute REQUIREMENTS fire separations into areas not

exceeding 600m2.



All Other Floor Assemblies 3 Must be fire separation; 4 No special requirements.45-minute fire-resistance rating if of combustible construction.

Mezzanines 4 No special requirements.2 4 No special requirements.

Roof Assemblies 4 No special requirements. 4 No special requirements.

Loadbearing Walls, 3 Loadbearing elements 3 No special requirements Columns, Beams, Arches supporting assemblies required to except that fire separation floor

have a fire-resistance rating must over basements must be supportedhave a 45-minute fire-resistance by a 45-minute rated assembly.rating or be of unrated noncom-bustible or combination except thatfire separation floor over basementsmust be supported by a 45-minuterated assembly.


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F2Industrial

Factories, RepairGarages, ServiceStations andWarehouses


MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 1 2 3 4

MAXIMUM Sprinklered [3.2.2.67.] [3.2.2.68.]BUILDING AREA Unlimited. 18 000 9000 6000 4500m2

CONSTRUCTION Basements 1 Noncombustible 1 Noncombustible construction.REQUIREMENTS construction.





resistance rating.2

Roof Assemblies 2 Heavy timber in 2 Heavy timber in buildings up to two storeys buildings up to two or noncombustible construction. 3

storeys or noncom-bustible construction.3

Loadbearing Walls, 1 Fire-resistance 1 Fire-resistance rating must equal that Columns, Beams, Arches rating must equal required for the supported assembly. 3

that required for the supported assembly. 3





F2Industrial

Factories, RepairGarages, ServiceStations andWarehouses



MAXIMUM Unsprinklered [3.2.2.69.] [3.2.2.71.]BUILDING AREA facing 1 street 1500 1500 1070 Not permitted. 1000 600m2 facing 2 streets 1500 1500 1340 Not permitted. 1250 750

facing 3 streets 1500 1500 1500 Not permitted. 1500 900

Sprinklered [3.2.2.70.] [3.2.2.72.]9600 4800 3200 2400 4500 1800

CONSTRUCTION Basements 3 Subdivided by 45-minute fire separations 3 Subdivided byREQUIREMENTS into areas not exceeding 600m2, unless 45-minute fire sep-

sprinklered. arations into areas not exceeding 600m2, unless sprinklered.

Floor Assemblies Above 3 45-minute fire separation. 3 45-minute fire Basements separation.

Floor Assemblies Above 4 No special requirements. 4 No specialCrawl Spaces requirements.

All Other Floor Assemblies 3 45-minute fire separation. 3 Must be fire sepa-ration; 45-minute fire-resistance rating if of combustible construction.

Mezzanines 3 45-minute fire-resistance rating if of 4 No special combustible construction.2 requirements.

Roof Assemblies 3 45-minute fire-resistance rating if of 4 No special combustible construction, waived for 1-storey requirements.2

buildings with FRTW roof systems or if buildingis sprinklered or unrated noncombustible.

Loadbearing Walls, 3 Loadbearing elements supporting 3 Loadbearing ele-Columns, Beams, assemblies required to have a fire-resistance ments supportingArches rating must have a 45-minute fire-resistance assemblies required to

rating or be of unrated noncombustible or have a fire-resistancecombination except that fire separation floor rating must have a 45- over basements and other fire separation floors minute fire-resistancemust be supported by an assembly of at rating or be of unratedleast equivalent rating. noncombustible or

combination except thatfire separation floor overbasements must be supported by a 45-minute rated assembly.


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F3Industrial

Laboratories,Sales Rooms,Storage Garagesand Workshops


MAXIMUM BUILDING HEIGHT, STOREYS Unlimited 1 2 3 4 5 6

MAXIMUM Unsprinklered [3.2.2.74.]BUILDING AREA facing 1 street Not permitted. Unlimited. 7200 4800 3600 2880 2400m2 facing 2 streets Not permitted. Unlimited. 9000 6000 4500 3600 3000

facing 3 streets Not permitted. Unlimited. 10 800 7200 5400 4320 3600

Sprinklered [3.2.2.73.] [3.2.2.75.]Unlimited. Unlimited. 21 600 14 400 10 800 8640 7200

CONSTRUCTION Basements 1 Noncombustible 1 Subdivided by 1-hour fire separations intoREQUIREMENTS construction. areas not exceeding 600m2, unless sprinklered.5

Floor Assemblies Above 1 2-hour fire 1 1-hour fire separation.1

Basements separation.1, 4


All Other Floor Assemblies 1 2-hour fire 1 1-hour fire separation.1

separation.1, 4

Mezzanines 1 1-hour fire 1 1-hour fire-resistance rating.2

resistance rating.2

Roof Assemblies 2 Heavy timber 2 1-hour fire-resistance rating unless sprinklered.3

in buildings up totwo storeys or non-combustibleconstruction.3

Loadbearing Walls, 1 Fire-resistance 1 Fire-resistance rating must equal that requiredColumns, Beams, Arches rating must equal for the supported assembly.3

that required for the supportedassembly.3





F3Industrial




MAXIMUM Unsprinklered [3.2.2.76.] [3.2.2.78.]BUILDING AREA facing 1 street 4800 2400 1600 1200 1600 800m2 facing 2 streets 6000 3000 2000 1500 2000 1000

facing 3 streets 7200 3600 2400 1800 2400 1200

Sprinklered [3.2.2.77.] [3.2.2.79.]14 400 7200 4800 3600 7200 2400

CONSTRUCTION Basements 3 Subdivided by 45-minute fire separations 3 Subdivided byREQUIREMENTS into areas not exceeding 600m2, unless 45-minute fire sep-

sprinklered.5 arations into areas notexceeding 600m2, unless sprinklered.5

Floor Assemblies Above 3 45-minute fire separation.1 3 45-minute fireBasements separation.1

Floor Assemblies Above 4 No special requirements. 4 No special Crawl Spaces requirements.

All Other Floor Assemblies 3 Must be fire separation; 45-minute fire- 3 Must be fire sep-resistance rating if of combustible construction.1 aration; 45-minute

fire-resistance rating if of combustibleconstruction.1

Mezzanines 3 45-minute fire-resistance rating if of 4 No specialcombustible construction.2 requirements.

Roof Assemblies 3 45-minute fire-resistance rating if of 4 No specialcombustible construction, waived if sprinklered requirements.or for 1-storey buildings with FRTW roof systems if building area is not more than one-half values otherwise permitted; or unrated noncombustible construction.

Loadbearing Walls, 3 Loadbearing elements supporting 3 Loadbearing ele-Columns, Beams, Arches assemblies required to have a fire-resistance ments supporting

rating must have a 45-minute fire-resistance assemblies required torating or be of unrated noncombustible or have a fire-resistancecombination except that fire separation floor rating must have a 45-over basements must be supported by a minute fire-resistance45-minute rated assembly. rating or be of unrated

noncombustible orcombination except that fire separation floor over basements must be supported by a 45-minute rated assembly.


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F3Industrial



MAXIMUM BUILDING HEIGHT, STOREYS 1

MAXIMUM Unsprinklered [3.2.2.80.]BUILDING AREA facing 1 street 5600m2 facing 2 streets 7000

facing 3 streets 8400

Sprinklered [3.2.2.81.]16 800

CONSTRUCTION Basements 2 Subdivided by 45-minute fire separations into areas not REQUIREMENTS exceeding 600m2, unless sprinklered.5

Floor Assemblies Above 2 45-minute fire separation, heavy timber or noncombustibleBasements construction.1

Floor Assemblies Above 2 Heavy timber or noncombustible construction.Crawl Spaces

All Other Floor Assemblies Not applicable.

Mezzanines 2 Heavy timber or noncombustible construction.2

Roof Assemblies 2 Heavy timber or noncombustible construction.

Loadbearing Walls, 2 Heavy timber or unrated noncombustible or a combination thereofColumns, Beams, Arches except that fire separation floor over basements must be supported by

a 45-minute rated assembly.





F3Industrial

Power Plantsand Manufactureor Storage ofNoncombustibles


MAXIMUM BUILDING HEIGHT, STOREYS 1

MAXIMUM Unsprinklered or [3.2.2.82.]BUILDING AREA Sprinklered Unlimited.m2

USE AND Must be used solely for low fire load occupancies such as power OCCUPANCY generating plants or plants for the manufacture or storage of RESTRICTION noncombustibles such as asbestos, brick, cement, concrete or steel.

CONSTRUCTION Basements 1 Subdivided by 45-minute fire separations into areas not exceeding REQUIREMENTS 600m2, unless sprinklered.



All Other Floor Assemblies Not applicable.

Mezzanines 1 Noncombustible construction.2

Roof Assemblies 2 Noncombustible construction or, if sprinklered, heavy timber is permitted. 3

Loadbearing Walls, 1 Fire-resistance rating must equal that required for the Columns, Beams, Arches supported assembly. 3


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F3Industrial

Storage GaragesGroup F — Division 3

continued

MAXIMUM BUILDING 22m in height measured between grade and HEIGHT, m the ceiling level of the top storey.

MAXIMUM Unsprinklered or [3.2.2.83.]BUILDING AREA Sprinklered 10 000m2

USE AND Must be used as a storage garage; no other occupancy permitted above OCCUPANCY the garage. All storeys must be constructed as open air storeys and every RESTRICTION portion of each floor area must be within 60m of an exterior wall opening.


Floor Assemblies Above 1 45-minute fire separation.1

Basements

Floor Assemblies Above 1 Noncombustible construction.1

Crawl Spaces

All Other Floor Assemblies 1 Noncombustible construction.1

Mezzanines 1 Noncombustible construction.

Roof Assemblies 2 Noncombustible construction or, if sprinklered, heavy timber is permitted.3

Loadbearing Walls, 1 Noncombustible construction.3

Columns, Beams, Arches

Notes for Group F Occupancies:

1 Unprotected openings for vehicle ramps permitted through floor separations in storage garages [3.1.8.1.(2)[&[3.2.8.2.(2)].



4 Reduced to one hour for storage garage with all storeys having at least 25% of total area of perimeter walls on eachstorey open to outdoors and distributed to provide cross-ventilation.

5 Waived for storage garages having at least 25% of total area of perimeter walls on each storey open to outdoors anddistributed to provide cross-ventilation [3.2.1.5.(2)].


5StructuralFire Protection5.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

5.2 Fire Separations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133Continuity of Fire Separations . . . . . . . . . . . . . . . . . . . . . . . . . . 134Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

5.3 Fire-Resistance Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147Fire-Resistance Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147Availability of Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Alternative Test Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

5.4 Alternative Methods for Determining Fire-Resistance Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157Component Additive Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 157Fire and Sound Resistance Tables . . . . . . . . . . . . . . . . . . . . . . 166Calculating Fire Resistance of Glulam Timbers . . . . . . . . . . . . . 168Fire Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171Extrapolation of Data from Fire-Resistance Tests . . . . . . . . . . . . 172

5.5 Fire-Resistance Rating Requirements in the NBCC . . . . . . . 175History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175Fire-Resistance Rating Requirements for Structural Assemblies . . 176Floor Assemblies in Residential Occupancies . . . . . . . . . . . . . . 178Fire-Resistance Rating Requirements of Loadbearing Structural Elements . . . . . . . . . . . . . . . . . . . . . . . . 179Exceptions to Fire-Resistance Rating Requirements . . . . . . . . . 182

5.6 Fire Protection Requirements for Mezzanines and Atriums . . . 185

5.7 Fire Stops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

5.8 Sprinkler Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

Chapter 3 explained fire separation,fire resistance, and compartmenta-tion as means of satisfying theContain Fire by Constructionbranch of the NFPA Fire SafetyConcepts Tree. It also explainedNBCC limits on combustibility andflammability of building materialswhich limit fire growth and delayfull room involvement in a fire(flashover).

These restrictions cannot ensurethat a fire will not reach flashoverbecause little control exists overthe flammability of building contents such as furniture and furnishings. National Fire Incident Reporting System data suggests that about one infour fires will reach the fullydeveloped stage. This stage posesthe highest danger of the firespreading to the rest of the building.

The Contain Fire by Constructionbranch of the NFPA Fire SafetyConcepts Tree (Figure 3.1) has two parts: • Control Movement of Fire • Provide Structural Stability

The branch objective will only be met if both elements are satisfied.

The NBCC uses the followingmethods to achieve the ContainFire by Construction objective:• minimum fire-resistance

ratings • compartmentation • active protection in the form

of automatic sprinklers

The requirements for these formsof protection are determinedbased on occupancy and size ofbuilding. This ensures buildingoccupants time to evacuate andalso allows for fire departmententry.

This chapter explains: • fire separations as a system for

creating fire compartments • determining the fire resistance

of these assemblies• maintaining the integrity

of fire separations• requirements of firewalls• the advantages of sprinklers,

particularly with regard to theincreased use of wood products

• the requirements for mezza-nines and large openingsthrough floor assemblies such as atriums


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Wood stud wallassembly beingremoved fromthe furnaceafter a fire-resistance test

A fire compartment is like a boxdesigned to contain a fire for alimited time within a building.

Fire compartment is defined as:“an enclosed space in a buildingthat is separated from all otherparts of the building by enclosingconstruction providing a fire separation having a required fire-resistance rating.”

The rated fire separations, that is,the building floors and interiorwalls, are therefore the basic con-stituents of fire compartmentation.

Fire separation is defined as: “a construction assembly that acts as a barrier against thespread of fire.”

To achieve its purpose of contain-ing the fire by construction, a fireseparation must have fire resis-tance and continuity. There areexceptions to this in the NBCC.

There are instances where anassembly may need to be built as a fire separation to restrict thepassage of smoke and fire but maynot need a fire-resistance rating.In such cases the fire separationneed only remain in place longenough to ensure that occupantscan leave the area, or, until asprinkler system is activated that will control and usually suppress the fire.

Fire Separations 133

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5.2 Fire Separations

FIGURE 5.1

Large multi-unitbuildings aredivided byrated fire separations to create firecompartments

Example 5.1Occupancy: Group D, officeBuilding Height: two storeysBuilding Area: 1000m2

Sprinklered: no

Construction requirements: • The second floor assembly

must be a fire separation. Ifthe assembly is of combustibleconstruction, a 45 minute fire-resistance rating (FRR) is required. [3.2.2.55.]

• Construction supporting thesecond floor assembly can beunrated noncombustible con-struction but, if of combustibleconstruction, requires a 45minute FRR. [3.2.2.55.]

• The floor assembly over thebasement must be a fire separa-tion with a 45 minute FRRregardless of construction type,with all supports having atleast a 45 minute FRR. [3.2.1.4.]

As noted, a noncombustible floorassembly for the second floorwould not require a fire-resistancerating. However, it must still bedesigned as a fire separation, withall penetrations protected inaccordance with Subsection [3.1.9.]to prevent the passage of smokeand hot fire gases. Without a“required” fire-resistance rating,this noncombustible floor assem-bly, although constructed as a fire separation, would not be considered as one of the boundaryelements of a fire compartment(see definition of fire compart-ment).

Example 5.2Consider a public corridor in afloor area of an office buildingthat is sprinklered.

Construction requirements:• The partitions forming the

walls of a corridor must bebuilt as fire separations but no fire-resistance rating isrequired. [3.3.1.4.(3)]

In this case, the partitions forming the walls of a corridorneed only be designed to restrictthe passage of smoke and fire for a short period. The sprinkler system, depending on the heatrelease rate of the fire, shouldactivate within 10 minutes. Once activated, the sprinklerwaterspray is expected to limitfire growth and thereby smokeproduction, preventing the firefrom spreading beyond the room where it originated.

CONTINUITY OF FIRE SEPARATIONS

General

[3.1.8.1.] The NBCC requires thatall fire separations be constructedas continuous elements. Floors andinterior walls of a building mustincorporate openings to allow forthe passage of people and buildingservices. It is critical that theseopenings be protected so that thefire separation and the desiredcompartmentation are maintained.



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Fire rarely spreads from one fire compartment to another by burning through floors or walls.Fire usually spreads through:• concealed spaces in ceilings

or attics• heating, ventilating and

air-conditioning ducts• holes made through fire

separations for the passage of electrical wires

• open doors

Each fire separation openingmust be protected by a barrier or be fire stopped with materialsthat will withstand smoke andhot fire gases for a specified period. Concealed spaces must be given special consideration to ensure that they will not act as flues through which a fire may burn or smoke may spreadundetected.

It is common to run heating, venti-lating and air-conditioning ductsas well as plumbing, electricalcables and other building servicesabove a suspended ceiling. Thisceiling membrane may or may notcontribute to the fire-resistancerating of the floor assembly.

[3.1.8.3.(2)] Vertical fire separa-tions must be carried through theceiling, be tightly fitted to theunderside of the floor or roof, andhave the required fire-resistancerating over its entire height if(Figure 5.2A):• the ceiling membrane is

unrated• the floor or roof together with

the ceiling membrane weretested as an assembly

[3.6.4.2.] Vertical fire separationsmay be terminated at the under-side of the ceiling membrane if(Figure 5.2B):• the ceiling membrane has

an equivalent fire-resistancerating to that required for thevertical fire separation

• the ceiling membrane has a 30-minute fire-resistance rating where the vertical fire separation requires only a 45-minute fire-resistance rating

The concealed space above theceiling then becomes another compartment and is subject to fire stopping requirements (Section 5.7).

[3.1.8.3.(3)] Where a verticalshaft such as a stairwell goesthrough a floor assembly, asmoke-tight joint must be provid-ed where the floor assembly abutsthe shaft. This reduces the possi-bility of smoke spreading to upperfloors. The vertical separationswhich enclose the shaft must runcontinuously through all con-cealed spaces formed by suspendedceilings (Figure 5.3).

Protection of Openings by ClosuresThe most vulnerable points of fireseparations are the openings suchas doors and holes for the passageof building services. It is essentialthat these openings be protectedwith closures: doors, shutters, fire dampers, wired glass or glassblocks. Such devices or assembliesmust be rated for fire exposure in accordance with specific teststandards depending on the typeof closure.

FIGURE 5.2A

Continuity ofvertical fireseparations

FIGURE 5.2B

Continuity ofvertical fireseparations


Wood joist

Subfloor or roof deck

Fire separation withassembly rating

Services

Rated fire separation must extend to floor above

Wood floor joist

Subfloor or roof deck

Services

Fire separation withmembrane rating

Ceiling membrane

Rated fire separation need only extend to bottom of ceiling membrane

Wood floor joist

Fire compartment

Fire compartment

Assembly rating

Membrane rating

[3.1.8.4.] The NBCC referencesseveral ULC standards coveringdoors, window and glass blockassemblies, and fire dampers. Italso references NFPA 80,Standard for Fire Doors andWindows, which containsdetailed installation specifica-tions for most types of closures.

The NBCC imposes limits on thesize of openings permitted in fireseparations as follows:

[3.1.8.6.(1)] For fire separationshaving an unsprinklered fire compartment on either side:• maximum area permitted for

any one opening is 11m2

• no dimension greater than 3.7m • no limit to the number of

openings

FIGURE 5.3

Vertical shafts


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Vertical shaft suchas stair well

Penthouse

Need not besmoke tight

joint

Droppedceiling

Shaft must extend throughconcealed spaces to maintain

continuity

Must be smoketight joint

Must be smoketight joint

Fire separation

Fire-resistance rating ofshaft based upon use of shaft

and rating required forfloor assembly

[3.1.8.6.(2)] For fire separationshaving sprinklered fire compart-ments on both sides:

• maximum area permitted for any one opening is 22m2

• no dimension greater than 6.0m • no limit to the number of

openings

[3.1.10.5] For firewalls: • same restrictions on size and

width as for fire separations• aggregate width of openings

cannot exceed 25% of the walllength

[3.1.8.4.] Closures are classified by fire-protection ratings whilefire separations are classified byfire-resistance ratings. The test forfire-protection rating for closuresdoes not contain the heat transmis-sion criteria which is in the fire-resistance test for fire separations.As for fire separations, closuresmust be installed in the same wayas the tested assembly, includingframe and hardware.

[TABLE][3.1.8.4] The fire-protectionrating required for closures is lessthan the fire-resistance ratingrequired for fire separations because: • combustible materials are not

likely to be stored immediatelyagainst closures, such as doorsand windows

• closures for building servicesare a small non-structural portion of the fire separation

[3.1.8.10.] Door assemblies with a fire-protection rating of 20 minutes or greater are acceptableclosures for:

• fire separations with a fire-resistance rating not greaterthan 45 minutes in buildingsnot more than 3 storeys inbuilding height

• 1-hour rated fire separationbetween corridors and specificoccupancies such as sleepingrooms, classrooms, offices andlibraries

Wood doors can be used in theabove applications if:• they are tested and labelled by

a recognised testing agency inaccordance with ULC StandardCAN4-S104, Standard Methodfor Fire Tests of DoorAssemblies

• they are solid core wood doorsof minimum 45mm thicknessdesigned in conformance withULC Standard CAN4-S113,Standard Specification forWood Core Doors Meeting thePerformance Required byCAN4-S104 for Twenty MinuteFire-Rated Closure Assemblies

The installation requirement for noncombustible sills in NFPA80, Fire Doors and Windows, doesnot apply to 20-minute rated doors because the concrete slabsills it specifies are impractical in 45-minute rated wood-frameconstruction. Wood sills may beused for these applications.

[3.1.8.15.] There are limits to temperature rise on the unex-posed side of closures in the following instances:


• doors requiring a fire-protectionrating of 45 minutes or moreleading directly to exit enclo-sures from the floor area inbuildings over three storeys

• doors located between dead-end corridors and adjacentoccupancies where the corridorprovides the only access to exit,and the corridor is required tohave a fire-resistance rating

• doors in firewalls

These limitations are appliedbecause radiant heat from thesedoors could prevent occupantsfrom passing in front of them inexit stair shafts; it could alsoendanger people trapped in suitesin dead-end corridors with noother exit facilities. Table 5.1shows the temperature rise limitsand gives maximum permissibleareas of wired glass or glassblocks in doors and walls.

Wired glass and glass blocks limitthe passage of flames for a certainduration, but do not block radiantheat. Thus, in certain locations,they could restrict evacuation, or allow ignition of combustiblematerials on the unexposed side.With the exception of the specificinstances listed in Table 5.1, theNBCC allows wired glass and glassblocks to protect openings in fireseparations which require a fire-resistance rating. The ratingrequired must not be more thanone hour, and the glass or blocksmust conform to prescriptiveassembly requirements.

[3.1.8.11.] Closures in fire separations must remain closed or close automatically under fire

conditions to be effective. Doors,because of their size, are a partic-ular concern. The NBCC requiresself-closing devices on doors infire separations with the follow-ing exceptions:• doors between corridors and

classrooms in buildings of notmore than three storeys

• doors between corridors andoffices in buildings of not morethan three storeys provided thedoor is not located in a dead-end portion of the corridor

These closures are exempt becausebuilding height is limited andoccupants are alert. Doors inhealth care facilities are coveredby specific compartmentationrequirements.

Such protection cannot be over-emphasised in occupancies such ashotels and apartment buildings: a suite door left open could allowhot fire gases and smoke to fill acorridor.

[3.1.8.12.] Hold-open devices onclosures which close the door auto-matically in case of fire are allowed.These devices are generally:• activated by a fusible link

which will automatically closewhen a specified temperatureis reached, or

• controlled by an electromag-netic device which releases thedoor on a signal from a firealarm system or smoke detector

[3.1.8.12.] Conditions for use ofeach type of device depend on thelocation of the closure and arespecified in the NBCC.


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TABLE 5.1

Restrictions on temperaturerise and glazing for closures


MaximumTemperature Maximum Rise on Aggregate

Minimum Opaque Maximum Area of WiredRequired Portion of Area of Glass PanelsFire-Protection Unexposed Wired Glass and Glass BlockRating of Door Side of Door in a Door not in a Door

Location hour oC cm2 cm2

Between a dead- < 3/4 no limit no limit no limitend corridor and an adjacent 3/4 250 after 645 645occupancy where 1/2 hourthe corridor provides the onlyaccess to exitand is required to have a fire-resistance rating

Between an exit enclosure andthe remainder ofthe floor area in all ratings no limit 8,000 8,000buildings not morethan three storeysin building height

Between an exit 3/4 250 after 645 645enclosure and 1/2 hour the remainder of the floor area 1 1/2 250 after 645 645(except as 1 hourpermitted above)

2 250 after 645 6451 hour

In a firewall 1 1/2 250 after 645 01/2 hour

3 250 after 0 01 hour

Source: National Building Code of Canada, 1995

Protection of Small OpeningsFire separations have numeroussmall openings for building ser-vices. NBCC requirements ensurethat openings do not channel hotgases, smoke and flames to adjacentfire compartments. If a duct or pipe which penetrates a fire sepa-ration melts or collapses on the fire exposed side, heat and flamescan travel through the opening.This will circumvent the protec-tion offered by the fire separationassembly.

[3.1.8.7.] Most ducts that connecttwo fire compartments or thatpenetrate an assembly required tohave a fire-resistance rating, mustbe equipped with a fire damper.

[3.1.8.8.] Fire dampers are notrequired when the duct:

• penetrates a vertical fire sepa-ration not required to have afire-resistance rating

• is noncombustible and penetratesa horizontal fire separation notrequired to have a fire-resistancerating

• serves commercial cookingequipment

For ducts that are noncombustibleand have a melting point above760°C, fire dampers are notrequired when the duct:

• is continuous and penetrates arequired vertical suite separa-tion, in other than a Group Band Group C occupancy

• penetrates a fire separationenclosing a vertical servicespace, provided the duct is notconnected to any common riserand separately exhausts directly

to the outside at the top of theservice space

• is a branch duct connected toexhaust risers under negativepressure having upward airflow and the branch duct iscarried up into the riser atleast 500mm

• is a branch duct with a cross-sectional area not more than0.013m2 that serves air-condi-tioning units or combined air-conditioning and heatingunits and discharges not morethan 1.2m above the floor

[3.1.9.4.] Pipes penetrating fireseparations are required to benoncombustible except for the following:• when the fire compartments on

each side of the fire separationare sprinklered

• combustible water distributionpiping up to 30mm in diameteris permitted to penetrate a vertical fire separation if thepiping is sealed with a fire stop system with an F ratingequivalent to the fire-protec-tion rating for closures in thefire separation

• combustible drain, waste andvent pipes, not located in a vertical shaft, can be used ifthe piping is sealed with a firestop system with an F ratingequivalent to the fire-resis-tance rating of the fire separation

Combustible water pipingrequirements are more lenientbecause the piping is normallyfilled with water which protectsthe pipe. The requirements forcombustible drain, waste and vent


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pipes are more stringent becausethese are not filled with waterand are usually open to the out-side air which creates an internalstack effect (Figure 10.2).

[3.1.9.3.] Electrical wiring andoptical fibre cables penetratingan assembly required to have afire-resistance rating are requiredto be in noncombustible racewaysexcept for the following:• single conductor metal

sheathed cables with diametergreater than 25mm with combustible jacketing are permitted to penetrate a fireseparation provided the cablesare not grouped

• cables, including optical fibrecables, or wires, singly orgrouped, with combustibleinsulation, jackets or sheathesthat conform to Clause[3.1.5.17.(1)(a)], that do notexceed 25mm in diameter

Nonmetallic raceways containingany type of electrical wiring andcables, including optical fibrecables, are permitted to penetratean assembly required to have afire-resistance rating provided:

• the raceway exhibits a verticalchar of not more than 1.5mwhen fire tested in accordancewith Article [3.1.5.19]

• the diameter of the racewaydoes not exceed 25mm

[3.1.9.2.] The combustibilityrequirements for ducts, pipes orelectrical wiring in fire separa-tions apply only if these compo-nents were not fire tested in theassembly. If an assembly was testedin a standard fire-resistance test

with the building services incorpo-rated into it, and attained a rating,it can be used, regardless of theamount of combustible material itcontains. The assembly with thebuilding services has demonstratedits ability to sustain a load andresist flames and passage of hotgases as a system for the durationof the fire test.

A fire separation must offer a tightbarrier to perform its function.There must not be any gapsbetween a membrane and anythingthat penetrates the separation. Thisapplies even if the penetrating itemis noncombustible.

[3.1.9.1.] The NBCC requires thatpenetrations through a membraneforming part of an assemblyrequired to have a fire-resistancerating or a fire separation be:• tight fitting or • sealed at the perimeter by a

fire stop system conforming to ULC Standard CAN4-S115,Standard Method of Test ofFire Stop Systems

These fire stop systems are, for themost part, proprietary systemswhich can resist the passage offlames for a given duration. Thetest evaluates these systems with-out testing an entire assembly.

FIREWALLS

The firewall performs the functionof separating adjoining buildingssharing a common lot line, to pro-tect the second property for as longas it takes for a fire to burn itselfout on the first property. This isthe main reason why masonry or



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FIGURE 5.4

Wood joists innon-combustiblefire separationsor firewalls

FIGURE 5.5

Fire wall connectiondetails

38 x 140 purlins

Masonry block wall

Anchor boltsfastened to concrete

filled block

Clip angle

Glulam beam

Masonry block pilaster

Ledger with anchorbolt embedded in concrete filled block

Offices

Second floor assembly

Ledger with anchorbolt embedded in concrete filled block

Offices

Warehouse

Note:As shown in Figure 5.6

Minimum thickness for requiredfire-resistance rating

Fire cut

Noncombustible fire separationor firewall

Wood beam or joist

Noncombustible fire separationor firewall

Wood beam or joist

Pilaster

concrete construction must beused. Depending on the occupan-cies it separates, a firewall mayrequire a fire-resistance rating oftwo or four hours.

[3.1.10.] Firewalls are a special type of fire separation that mustwithstand prolonged fire exposurefrom either side without collapse.The requirements for firewallsare:• constructed of masonry or

concrete• adjoining construction on the

fire exposed side can collapsewithout affecting it (must be afree-standing structure)

• a fire-resistance rating of 2 or 4 hours

• must extend through all storeysfrom the basement slab upthrough the roof

• must terminate at a roof slabof reinforced concrete with afire-resistance rating equal tohalf of the firewall, or mustextend through the roof whereit must form a parapet of150mm for a two hour wall or900mm for a four hour wall

• openings in firewalls have thesame restrictions on size andwidth as fire separations [3.1.8.6.]

• the aggregate width of open-ings cannot exceed 25% of thewall length [3.1.10.5.]

• combustible projections, suchas balconies, on one side of afirewall are not permittedwithin 2.4m of window anddoor openings or combustibleprojections on the other side ofa firewall


FIGURE 5.6

Erection oftrusses onto a firewall

[2.1.6.1.] A firewall can be aparty wall separating two proper-ties built on the lot line. It canalso subdivide a building so thateach portion is considered as a separate building for the purposeof determining the minimum fireprotection requirements. A largebuilding requiring noncom-bustible construction may bedivided by firewalls so that eachsection is small enough to permitthe use of wood-frame construction.

[3.1.10.1.] Although firewallsmust be made of masonry or con-crete, wood roof constructions canbe used effectively with parapetedfirewalls. Wood floors can beframed into firewalls provided thatthe thickness of the masonry orconcrete necessary for the requiredfire resistance is maintained. Joistconnections and supports must bedesigned so that the collapse of the floor during a fire will notcause the collapse of the firewall (Figures 5.4 to 5.6).


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FIGURE 5.7

Firewall support

Firewall support on ground

Firewall above a basement

storage garage

Brick or concrete

Reinforced concrete

Firewall separatingbuildings with roofs

at different elevations

Offset firewall supportedon structural frame

ConcreteParapetnot required if

difference inelevation is greater

than 3m

Brick or concrete

[3.1.10.7.] Wood construction canalso be used in exterior walls withfirewalls having smoke-tightjoints similar to the roof-firewallintersection. To prevent flamesfrom jumping across or around afirewall, combustible balconies, platforms, stairs, eaves or otherprojections are not permittedwithin 2.4m of similar combustibleprojections or window or door open-ings on the adjoining building.

[3.1.10.4.] A firewall must extendthrough all storeys from thebasement slab up through theroof where it must form a para-pet 150mm or 900mm high abovethe roof surface, depending onwhether the wall requires a two- or four-hour rating. Theparapet protects fire-fighters and prevents the fire fromspreading to the other side.

[3.1.10.3.] The firewall may, how-ever, terminate at the undersideof a roof slab that has, on bothsides, a fire-resistance ratingequal to half that required for thefirewall, provided there is no con-cealed space above. Even if a firebreaches the roof slab on one sidein half the time, it will take aslong for the fire to break throughthe slab on the other side.

[3.1.10.1.(3)] A firewall may alsobe supported on noncombustibleconstruction having the same fire-resistance rating. This allows, forinstance, parking garages to spanbelow several building parts considered as separate buildingsfor the purpose of determiningfire protection requirements (Figure 5.7).

[3.1.10.2.(1)] A firewall need nothave the same fire-resistance rat-ing throughout. In a multi-storeybuilding with lower floor occupan-cies requiring a four-hour firewalland upper-floor, less hazardousoccupancies requiring a two-hourfirewall, the rating of the firewallseparating the upper-floor occu-pancies can be reduced to twohours. The reverse is not allowedbecause construction supportingthe firewall must have at least anequal rating.

[3.1.10.5.] Firewall openings aresubject to the same size limits asfire separation openings and theaggregate width of openings can-not exceed 25% of the wall length.Openings must be protected by closures and, in the case of building services such as pipes, the gap between the wall and thepenetrating component must besealed by a fire stop system.


Fire separations must be designedto resist the effects of fire for agiven time based on its expectedseverity in a compartment.

Fire-resistance rating is definedin part as: “the time in hours orfraction thereof that a materialor assembly of materials willwithstand the passage of flameand the transmission of heatwhen exposed to fire under specified conditions of test andperformance criteria…”

HISTORY

Since the early 1920s, the conven-tional way to establish fire-resis-tance rating has been to subject a representative sample of the construction to a standard fire testperformed in special furnaces. The test methods and furnaces dateback to the end of the last century.

In the late 1800s, building regula-tions consisted of cumbersomeprescriptive requirements whichspecified materials and methodsof assembly. These were deemed tooffer an acceptable level of fireprotection based on observationsat fire sites. Such regulationswere limiting and did not allowfor innovative solutions.

Eventually, with increasing pressure from designers and manufacturers promoting new products and constructionsystems, researchers subjectedrepresentative floor specimens toexposure from a standard woodcrib fire which lasted from eightto 24 hours.

This evaluation procedure becamea standard test method across the US and was published by the American Society for Testingand Materials (ASTM) in 1908.ASTM standard test criteria wereadopted by other organisationsincluding the Underwriters’Laboratories of Canada. Theyremain largely unchanged today.

FIRE-RESISTANCE TESTING

Representative samples of assemblies are tested in furnaces.Test assemblies are large enoughto simulate the floor or wallenclosing a small room as follows:• floor specimens must be almost

17m2 with no side less than3.7m

• walls must be slightly over 9m2

with no dimension less than2.75m

• building columns must be notless than 2.75m in height

Three different furnaces weredeveloped, for walls (Fig 5.8),floors (Fig. 5.9) and columns (Fig. 5.10), to replicate the different fire exposures.

Horizontal Assemblies

]3.1.7.3.(1)] Horizontal assembliessuch as floors, ceilings and roofsare tested for fire exposure fromthe underside only. This is becausea fire in the compartment belowpresents the most severe threat.For this reason, the fire-resistancerating is required from the underside of the assembly only.

Fire-Resistance Ratings 147

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5.3 Fire-Resistance Ratings

Horizontal assemblies, when tested, are built as the top of the furnace and are subjected to a superimposed load. This load isnormally equal to the maximumallowable design load permitted by the applicable design standard.The loads are typically appliedfrom above by hydraulic jacks. Ifconducted under a reduced load,the test report must include such a limitation.

Floor and roof assemblies may or may not have end restraint (lateral displacement and rotationprevented) when constructed. If the assembly is tested underrestrained conditions, it offersmore resistance to thermal displacements and implies additional fire resistance for the loadbearing assembly.

FIGURE 5.8

Fire test furnace forfloors androofs

FIGURE 5.9

Fire test furnace forwalls


Flues

Specimen

Thermocouple tubes

Restraining frame

Observation ports

Furnace (loading devicenot shown)

Gas burners

Observationports

Thermocoupletubes

Gas burners

Furnace

Specimen (under construction)

Restraining frame

Loading jacks(when required)

Flue

The fire-resistance rating of thetested assembly will indicate, aspart of the listing limitations, the restraint conditions of thetest. When selecting a fire-resis-tance rating, it is important toensure that the restraint condi-tions of the test are the same asthe construction in the field. Woodframe assemblies are normallytested with no end restraint tocorrespond with normal construc-tion practice.

Vertical Assemblies

[3.1.7.3.(2)] Partitions or interiorwalls required to have a fire-resistance rating must be ratedequally from each side since a fire could develop on either side of the fire separation. They arenormally designed symmetrically.If they are not symmetrical, thefire-resistance rating of theassembly is determined based on testing from the weakest side.

Figure 5.9 illustrates the furnaceused for testing vertical assem-blies. The wall assembly formsone side of the furnace creating a closed four-sided box.

For a loadbearing wall, the testrequires the maximum load permitted by design standards besuperimposed on the assembly. Mostwood-stud wall assemblies are testedand listed as loadbearing. Thisallows them to be used in both loadbearing and non-loadbearingapplications. Most steel-stud wallassemblies are tested and listed asnon-loadbearing because they areused primarily in non-loadbearingapplications in noncombustiblebuildings.

Loadbearing steel-stud wallassemblies typically use studs of a heavier gauge steel than non-loadbearing studs to be able tosupport the load. The heaviergauge stud reacts differentlywhen exposed to fire and with-stands the tendency for studs totwist and distort when exposed toheat. Loadbearing and non-load-bearing steel stud wall listingsare not interchangeable becausethe properties of the studs in these assemblies are not the same.Listings for loadbearing wood studwalls can be used for non-load-bearing cases since the same studsare used in both applications.

Loading during the test is criticalas it affects the capacity of the wallassembly to remain in place andserve its purpose in preventing firespread. The strength loss in studsresulting from elevated tempera-tures or actual burning of struc-tural elements causes deflection.This deflection affects the capacityof the protective wall membranes(gypsum wallboard) to remain inplace and contain the fire. The fire-resistance rating of loadbearingwall assemblies is typically lowerthan that of a similarly designednon-loadbearing assembly.

[3.1.7.3.(3)] Exterior walls onlyrequire rating for fire exposurefrom within a building. This isbecause fire exposure from the exterior of a building is not likelyto be as severe as that from a fire inan interior room or compartment.Because this rating is requiredfrom the inside only, exterior wall assemblies do not have to besymmetrical.


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[3.1.7.2.(1)] The acceptance criteriain the standard fire-resistancetest method (see insert page 151)limits the maximum temperaturerise on the unexposed face (side oftested assembly outside the testfurnace). This maximum tempera-ture rise criteria does not apply toexterior walls used where the lim-iting distance is 1.2m or greater.

Temperature transmission limitsare specified in the test to guardagainst the possibility of ignitingcombustible materials which maybe against the wall in an adjacentroom. If a fire separation restrictsthe passage of flame but allowsthe temperature on its unexposedside to rise high enough to ignitecombustible materials, it will nothave performed its function ofresisting fire spread.

This situation does not apply to anexterior wall. However, other NBCCrequirements (in Subsection [3.2.3.])concerning the potential increasein radiation exposure to adjacentbuildings will apply in this case(Chapter 7).

If a listed wall assembly was testedwith gypsum wallboard on bothsides of the wall assembly, and isused as an exterior wall design, itmust still be constructed exactly astested. The requirement for a rat-ing only from within the building,does not permit the gypsum wall-board membrane on the outsideface of the wall to be omitted.

The column furnace shown inFigure 5.10 is designed to test the column under its expected service load. Usually, this is done

FIGURE 5.10

Fire test furnace forcolumns


Restraint frame

Insulated furnaceshell

Burners

Transverse loading head

Test column

Axial loading arm

under axial loading. The furnaceat the Institute for Research inConstruction (IRC) in Ottawa isthe only one in Canada that cantest columns under eccentricloads, and expose columns to firefrom all sides at the same time.

Standard Fire Test

[3.1.7.1.] The test and acceptancecriteria the NBCC refers to are contained in a standard fire testmethod, CAN/ULC-S101, StandardMethod of Fire Endurance Tests of Building Construction and Materials, published byUnderwriters’ Laboratories ofCanada (see insert below).


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ULC S101, Standard Method ofFire Endurance Tests of BuildingConstruction and Materials

Criteria for testing and accep-tance in this test method differaccording to assembly type. Theassigned fire-resistance rating foran assembly is the length of timeit can withstand the standard fireexposure, based on a standardtemperature-versus-time rela-tionship (see insert page 152)while still satisfying the following criteria:• permit no passage through

the assembly of heat orflames hot enough to ignitecotton waste

• specimen to remain in placeunder design loads (for load-bearing assemblies only)

• temperature rise on theunexposed surface (wall orfloor surface outside the testfurnace) of specimen limitedto 139°C (average of ninepoints measured) and 181°C(maximum at any point)

• no passage of hose streamthrough the assembly (verticalwall assemblies only).

The first two criteria are self-explanatory. The third is

intended to prevent the ignitionof combustibles located directlyagainst the unexposed floor orwall membrane in the adjacentcompartment.

The hose stream criterion isonly used for walls which musthave a fire-resistance rating ofone hour or more. This isintended to ensure a minimumresistance to the cooling anderosion effects of a hose streamthat might be directed at thewall during firefighting. Anassembly is first tested to deter-mine its fire-resistance rating.A duplicate assembly is thenconstructed and submitted tothe fire test but removed fromthe furnace at the half waypoint. The hose stream test isperformed on the duplicatespecimen at that point.

For loadbearing columns, thespecimen need only sustain theapplied load for the duration ofthe test. For protected steelcolumns, where the protectiondoes not contribute to loadbear-ing, an applied load is notrequired, but the average temper-ature of the steel must not exceed538 °C nor may the temperatureat any point exceed 649 °C.

The ULC fire-resistance test maybe used to establish the fire-resis-tance rating of a single materialor an assembly of materials. Sincefloors and walls usually have avariety of components, the test ismost frequently applied to entireconstruction assemblies. It

provides a relative measure of the fire resistance of the entireassembly, not that of its individu-al components. The fire-resistancetest is designed to evaluate anassembly as a complete system,whether it is of combustible ornoncombustible construction.


Standard Temperature-versus-Time CurveIn the standard fire test, the furnace temperature is controlledto follow the time/temperaturecurve shown here. Thiscurve was established in1918 using the maximumtemperatures in real fires.These temperatures weredetermined by observingthe fusion of materials withknown melting points inthe fires.

The curve is considered to represent average fire temperatures.Temperatures of actualfires vary according to:• the amount, type and

geometry of com-bustible contents in a compartment

• the availability offresh air

• the flame-spread andthermal conductivitycharacteristics of finishmaterials on the wallsand floor

Test results using thistime/temperature curveare accepted as an ade-quate representation ofthe expected performance

of the assembly in a real fire.This fire exposure is felt to besevere enough to challenge thefire-safety of the assembly.

2400

2200

2000

1800

1600

1400

1200

1000

800

600

400

200

1315.6

1204.4

1093.3

982.2

871.1

760.0

648.8

537.8

426.7

315.6

204.4

-17.80 1 2 3

Time (Hours)5 6 7 8

93.3

4

Deg

rees

Fah

renh

eit

Deg

rees

Cen

tigra

de

1000° F (538°C)1300° F (704°C)1550° F (843°C)1700° F (927°C)1850° F (1010°C)2000° F (1093°C)2300° F (1260°C)

at 5 minat 10 minat 30 minat 1 hrat 2 hrat 4 hrat 8 hr or over

Standard Time Temperature Curve

The greatest disadvantage of theconventional test approach is thatdesigners must conform to everyessential detail of the testedassemblies to obtain the listedfire-resistance rating. Even aslight modification such as type orspacing of fasteners could meanthat the fire-resistance rating isnot valid.

It may be necessary to test a newspecimen to ensure that the pro-posed modification will not reducethe fire resistance of the assembly.This can be very expensive andprevents new methods from beingeasily applied. There are someguidelines for extrapolation ofdata from fire-resistance testswhich may be accepted by theauthority having jurisdiction.These are detailed in Section 5.4.

AVAILABILITY OF TEST RESULTS

A multitude of fire-resistancetests have been conducted over thelast 70 years by North Americanlaboratories. Results are availablethrough:

• Underwriters’ Laboratories ofCanada

• Warnock Hersey ProfessionalServices Ltd.

• Underwriters’ LaboratoriesIncorporated

• Factory Mutual ResearchCorporation

In addition, manufacturers of construction products publishresults of fire-resistance tests on assemblies incorporating their proprietary products

(for example, Gypsum Association’sFire Resistance Design Manual).(The addresses for these referencesare listed in the InformationSource of the Appendix).

Testing laboratories and manufac-turers also publish information onproprietary listings of assemblieswhich describe all materials usedand assembly methods. Figures5.11 and 5.12 reproduce informa-tion from one of these sources.

The listings are useful because they offer off-the-shelf solutions todesigners. They can, however,restrict innovation because design-ers use assemblies which havealready been tested rather than payto have new assemblies evaluated.Listed assemblies must be used withthe same materials and installationmethods as those tested.

[A-9.10.3.1.A] A recent researchproject at NRC resulted in over onehundred different wall assembliesbeing assigned fire-resistance and sound transmission ratings.These results are published inNBCC Table A-9.10.3.1.A. Not all assemblies described wereactually tested. The fire-resis-tance ratings for some assembleswere extrapolated from fire testsdone on similar wall assemblies.

Although there is no direct reference to Table A-9.10.3.1.A inPart 3, the fire-resistance ratingslisted have been determined on the basis of tests conducted inaccordance with the ULC-S101standard referenced in Part 3.


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FIGURE 5.11

Listed woodjoist floorassembly


6

3

7 5

235

15.9

19

1515

2525

75

End joint detail

8

7

6

21 4

Design No. M503 Unrestrained Assembly Rating: 2h

Combustible Construction(Finish Rating - 75 minutes)

1. Finish Flooring: 19 x 89mm T & G flooring laid perpendicular to joists or 15.5mm select sheathing grade T & G phenolic bonded Douglas Fir plywood with face grain perpendicular to joists and joints staggered.

2. Building Paper (optional): Commercial sheathing material, 0.25mm thick.3. Sub-flooring: 19 x 140mm T & G boards laid diagonally to joists or 12.5mm unsanded sheathing grade phenolic bonded

Douglas Fir plywood with face grain perpendicular to joists and joints staggered.4. Bridging: 19 x 64mm.5. Wood Joists: 38 x 235mm spaced 400mm O.C., firestopped.6. Furring Channel: Resilient, formed of 0.5mm electrogalvanized steel as shown, spaced 600mm O.C. perpendicular to joists.

Channels overlapped at splice 38mm and fastened to each joist with 63mm common nails. Minimum clearance of channels towalls, 20mm. Additional pieces 1500mm long placed immediately adjacent to channels at end of joints of second layers; endsto extend 150mm beyond each side of end joint.

7. Gypsum Wallboard: (Guide No. 40U18.23). 15.9mm thick, 1200mm wide. First layer of wallboard installed with long dimensionperpendicular to joists and end joints of boards located at the joists. Nailed to joists with uncoated 63mm box nails spaced180mm O.C. All nails located 15mm minimum distance from the edges and ends of the board. Second layer of wallboardsecured to furring channels by 25mm long wallboard screws. Second layer installed with long dimension perpendicular to the furring channels and centre line of boards located under a joist and so placed that the edge joint of this layer is not inalignment with the end joint of the first layer. Secured to furring channels with wallboard screws 300mm O.C. with additionalscrews 75mm from side joints. End joints of wallboard fastened at additional furring channels as shown in end-joint detail. All screws located 25mm minimum distance from edges of boards.

ATLANTIC GYPSUM, a division of the Lundrigans-Comstock LimitedDOMTAR INC.GEORGIA PACIFIC CORPORATIONWESTROC INDUSTRIES LIMITED

8. Wallboard screws: Type S Phillips self-drilling and self-tapping 25mm long.9. Joint System (not shown): Paper tape embedded in cementitious compound over joints and exposed nail heads covered with

compound, with edges of compound feathered out.

Reprinted by permission of Underwriters Laboratories of Canada.

ALTERNATIVE TEST STANDARDS

The NBCC permits the authorityhaving jurisdiction to acceptresults of tests performed according to other standards.Since test methods have changedlittle over the years, results basedon earlier or more recent editionsof the CAN/ULC-S101 standardare comparable.

The primary US fire-resistancestandard, ASTM E119, is very similar to the CAN/ULC-S101 standard.

Both use the same time-tempera-ture curve and the same perfor-mance criteria. Fire-resistanceratings developed in accordancewith ASTM E119 are usuallyacceptable by Canadian officials.Whether an authority havingjurisdiction accepts the results oftests based on these standardsdepends primarily on the offi-cial’s familiarity with them.

FIGURE 5.12

Listed woodstud wallassembly


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4 1 38 x 89mm

400 O.C.400 O.C.

3 2Firestopped

Design No. U301 Assembly Rating: 2h

Bearing Wall - Combustible Construction(Finish Rating - 66 minutes)

1. Nailheads: Exposed or covered with joint finisher.2. Joints: Exposed or covered with tape and joint finisher.3. Nails: 51mm, cement-coated flathead.4. Gypsum Wallboard: (Guide No. 40U18.23),15.9mm thick applied in two layers.

Base layer placed vertically with joints butted over studs and nailed to studs 150mm O.C.Face Layer applied horizontally with joint finisher cement and nailed 300mm O.C. temporarily to base layer until cement sets.All joints in face layers staggered with joints in base layers and with joints on opposite sides.

Canadian Gypsum Company, Limited, A division of CGC Inc.Domtar Inc.

Reprinted by permission of Underwriters’ Laboratories of Canada.

The previous chapter on fire-resistance ratings deals with thedetermination of fire-resistanceratings from standard tests. Thischapter features alternativemethods for determining fire-resistance ratings which are permitted by the second part of thefire-resistance rating definition.

Fire-resistance rating is definedas: “the time in hours or fractionthereof that a material or assem-bly of materials will withstandthe passage of flame and thetransmission of heat when exposedto fire under specified conditionsof test and performance criteriaor as determined by extensionor interpretation of informa-tion derived therefrom as prescribed in this Code.”

[3.1.7.1.(2)] This interpretationof information from tests appliesto the alternative methods ofdetermining fire-resistance ratings as contained in the NBCCAppendix D, Fire-PerformanceRatings. These alternative calculation methods can replaceexpensive proprietary fire tests. In some cases, these allow lessstringent installation and designrequirements such as alternate fastener details for gypsum wallboard and the allowance ofopenings in ceiling membranes forventilation systems.

Section D-2 in NBCC Appendix Dincludes methods of assigningfire-resistance ratings to:• masonry and concrete walls• reinforced and prestressed

concrete floor and roof slabs

• wood-and steel-framed walls,floors and roofs

• glue-laminated timber beamsand columns

• concrete filled hollow steelcolumns

COMPONENT ADDITIVE METHOD

[D-2.3.] The most practical alternative calculation method,includes procedures for calculat-ing the fire-resistance rating oflight wood- and steel-frame wall,floor and roof assemblies based ongeneric descriptions of materials.This component additive method(CAM) can be used when it is clearthat the fire-resistance rating ofan assembly depends strictly onthe specification and arrangementof materials for which nationallyrecognized standards exist.

CAM was developed in the early1960s by a technical committeefrom an analysis of fire-test data.The estimates are conservativesince the assigned ratings mustapply to all systems and productscovered by the material standarddescription. The assemblies mustconform to all requirements inNBCC Appendix D for the ratingto be valid.

[3.1.7.3.] The NBCC requires that exposure conditions for fire-resistance ratings be based on thefollowing: • floor, roof and ceiling assemblies

shall be rated for exposure to fireon the underside

Alternative Methods for Determining Fire-Resistance Ratings 157

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5.4 Alternative Methods for Determining Fire-Resistance Ratings

• firewalls and interior verticalfire separations shall be ratedfor exposure to fire on eachside

• exterior walls shall be rated forexposure to fire from inside thebuilding

For light frame assemblies, CAMrelates to the fire performance of walls or partitions with fireexposure from one side only. For afloor or roof assembly, the methodis based on fire performance whenfire exposure is from below.

[D-2.3.1.] CAM can be used toassign a fire-resistance rating of up to 90 minutes.

[D-2.3.2.] The ratings apply to:• non-loadbearing and loadbearing

wood-stud walls and partitions • non-loadbearing steel-stud

partitions• loadbearing wood joist and

wood truss floor and roofassemblies

• open-web steel joist floor androof assemblies

[D-2.3.6.(2)] CAM can be used for wood-frame floor and roofassemblies with wood joists andmetal-plate connected wood trusses (both pitched and parallelchord design). Wood joists andmembers of trusses must not beless than 38 x 89mm.

This calculation method does notapply to assemblies incorporatingwood trusses with metal-tube or bar webs, nor to wood I-joists.

Manufacturers of these productshave proprietary listings ofassemblies incorporating theseelements with fire-resistance ratings ranging from 45 minutesto two hours.

[D-2.3.6.(5)] CAM cannot be usedto assign fire-resistance ratings toloadbearing steel-stud wall assem-blies. Light gauge steel studs usedin any non-loadbearing partitionor in any wall requiring a fire-resistance rating must be installedwith a clearance of at least 12mmbetween the top of the stud and thetop runner to allow for expansionin a fire. Because it may expandand twist under heat, the top of thesteel stud may not be attached tothe top runner by screws, welding,crimping or any other method.

[D-2.3.4.(1)] In applying theComponent Additive Method, the fire-resistance rating of anassembly is calculated by adding:• the time assigned to the protec-

tive membranes (wallboard orceiling membranes) on the fire side

• the time assigned to the structural framing members

• the time allowed for membranereinforcement, if applicable

• the time allowed for provisionof some types of insulationwithin the assembly

[D-2.3.6.(6)] Although resilientand gypsum wallboard furringchannels were not common whenthe calculation method was devel-oped, fire research shows that thefire-resistance rating of floor


assemblies is not reduced by them.They are now permitted in floor orroof assemblies without reduction inassigned values.

Recent research at NRC on thefire-resistance rating of walls hasshown that the use of resilientchannels may reduce the ratingsin certain applications. The current calculation method inAppendix D does not reflect this.However, the fire-resistance andacoustic ratings contained inTable A-9.10.3.1.A., are based onthis latest research.

[D-2.3.5.(4)] Fire research showsthat insulation, depending on how and where it is positioned andheld in place within the floor/roofassembly, can reduce the fire-resistance values of an assembly.For this reason, a floor or roofassembly with a fire-resistancerating determined by CAM is only permitted insulation if it isinstalled and supported within theassembly as described in D-2.3.5.(4).

[D-2.3.4.] Table 5.2 lists the timethe Appendix assigns to variouswall membranes, based on the

ability of the membrane to stay inplace during the standard firetest. The 1995 NBCC has removedregular gypsum wallboard, fibre-board and also asbestos cementboard from the finishes permittedto be used with this method. Inaddition, the values assigned toDouglas fir plywood can only beused in non-loadbearing wallswith mineral fibre insulation inthe walls and the 15 minute creditfor mineral fibre insulation doesnot apply.

The values for regular gypsumwallboard were removed becausethe minimum density requirementfor regular gypsum wallboard was lowered in the revised CSAstandard, CSA A82.27-M91, Gypsum Wallboard. Gypsum wallboard manufactured to thenew minimum requirements of the standard has a lower fire-resistance than that from earlier generations. As thismethod permits the use of anymembrane which meets the minimum requirements of thestandard, the listing was removed.

TABLE 5.2

Time assignedto wallboardmembranes


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Description of Finish Time, minutes

11.0mm Douglas fir plywood phenolic bonded 101

14.0mm Douglas fir plywood phenolic bonded 151

12.7mm Type X gypsum wallboard 2515.9mm Type X gypsum wallboard 40Double 12.7mm Type X gypsum wallboard 802

Notes:1. Non-loadbearing walls only, stud cavities filled with mineral wool conforming to CSA A101-M, Thermal Insulation, Mineral Fibre,

for Buildings and having a mass of not less than 2kg/m2, with no additional credit for insulation according to Table D-2.3.4.D.2. This value applies to non-loadbearing steel framed walls only.

Source: Appendix D, National Building Code of Canada, 1995, Table D-2.3.4.A.

There are still many proprietarylistings which specify regulargypsum wallboard of particularmanufacturers. These productsare above the minimum standardsand can still be used. The removalof the minimum density require-ments did not affect the timeassigned to Type X gypsum wall-board. The recent fire research at NRC did result in new fire-resistance ratings being assignedto wood stud wall assemblies protected by regular gypsum wallboard in ]TABLE[[A.9.10.3.1.A].

[D-2.3.4.(3)] Table 5.3 lists thetimes assigned to various struc-tural framing members. Thesetimes are based, in part, on the timeto structural failure of unprotectedassemblies in a fire test. This recog-nises that the structural compo-nents stay in place for some timeafter the wallboard falls away.

While wood stud framing at400mm o.c. is assigned a value of20 minutes, a value of 15 minutesfor wood studs spaced at 600mmo.c. has been added in the 1995NBCC based on fire tests thatwere performed at NRC in the

late 1980’s. The latest research performed in 1994 and 1995 atNRC resulted in identical fire-resistance ratings being assignedto wood stud walls with studs ateither 400 or 600 mm o.c. This isreflected in the listings containedin ]TABLE[[A.9.10.3.1.A].

[D-2.3.5.(1)] For fire-resistancerated interior partitions, theNBCC requires ratings from both sides. CAM assumes that the wall assembly will be symmetrical in design with equivalent membrane protectionon each side. If the membranes differ, the fire-resistance ratingmust be determined on the basisof the membrane assigned thelowest time.

The membrane(s) on the non-fireexposed side of the assembly is notconsidered to contribute to thefire-resistance rating because it isassumed that this unexposedmembrane will collapse when theframing fails. This applies for allassemblies calculated with thismethod, whether it is a partition,floor, roof, or exterior wall.


Time Assigned to Frame

Description of Frame minutes

Wood studs max. 400mm o.c. (Loadbearing or non-loadbearing) 20Wood studs max. 600mm o.c. (Loadbearing or non-loadbearing) 15Steel studs max. 400mm o.c. (non-loadbearing) 10Wood floor and roof joists max. 400mm o.c. 10Open web steel joist floors and roofs with ceiling supports max. 400mm o.c. 10Wood roof and floor truss assemblies max. 600mm o.c. 5

Source: Appendix D, National Building Code of Canada, 1995, Table D-2.3.4.C.

TABLE 5.3

Time assignedfor contributionof wood or lightsteel frame

[D-2.3.3.(3)] Although Harmathy’sTen Rules of Fire Endurance, (seeend of Section 5.4) would suggestthat it is appropriate, the timesassigned to individual membranesfrom Table 5.2 can not be added to achieve a higher overall fire-resistance rating. The recent NRC research project did result invalues being assigned to assemblieswith multiple and asymmetricalmembrane combinations.

[3.1.7.3.(3)[&[D-2.3.5.(2)] Exteriorwalls are rated for exposure tofire from the interior side. Theydo not have to be symmetrical but must meet the following conditions to use this method:• the exterior membrane must

consist of sheathing and exterior cladding

• the spaces between the studsmust be filled with insulationconforming to CSA A101-M,Thermal Insulation, MineralFibre, for Buildings, having amass of not less than 1.22kg/m2

The mineral fibre insulation canbe either manufactured from rockslag (Rockwool) or from glassfibres (fibreglass). The valuesassigned in Table D-2.3.4.D canstill be used to increase theassigned fire-resistance rating ofthe exterior wall assembly.

As noted earlier, CAM cannot be used for loadbearing steel-studexterior walls requiring a fire-resistance rating. A listedfire-rated steel-stud assemblymust be used which, in manycases, requires gypsum wallboardon both the interior and exteriorfaces of the wall assembly.

[D-2.3.5.(3)] For floor and roofassemblies rated on the basis offire exposure from below, theupper membrane (subfloor/finishfloor; roof deck/covering) mustconsist of :• one of the combinations listed

in Table 5.4, or • a membrane in Table 5.2

assigned at least 15 minutes

These upper membranes areassumed to provide the minimumfire resistance necessary to maintain the assembly untilstructural collapse. In the case of14mm Douglas fir plywood inTable 5.2., the requirement forinsulation does not apply when itis used as a floor or roof mem-brane.

[D-2.3.12] In using CAM to determine the fire-resistance rating of a floor or roof assembly,a designer may choose a ceilingmembrane that contributes all of the rating. The times assignedto gypsum wallboard and othermembranes differ where the fire-resistance rating of a floor or roofassembly is determined based onthe contribution of the ceilingmembrane only, rather than onthe complete assembly. Table 5.5lists these values.

[D-2.3.6.(1)] Values listed inTables 5.2 and 5.5 are for use inassigning a fire-resistance ratingto an assembly using only theframing members described inTable 5.3. It is not intended to permit any type of framing member to be used with thisapproach of having the membrane


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TABLE 5.5

Fire-resistancerating for ceiling membranes

TABLE 5.4

Flooring orroofing overwood, coldformed steelmembers oropen-web steel joists


Type of Structural Subfloor or Finish Flooring Assembly Members Roof Deck or RoofingFloor Wood or steel joists 12.5mm plywood or Hardwood or softwood

and wood trusses 17mm T & G softwood flooring on building paperResilient flooring, parquet floor, felted-synthetic-fibre floor coverings, carpeting orceramic tile on 8mm thick panel-type underlayCeramic tile on 30mm mortar bed

Steel joists 50mm reinforced Finish flooringconcrete or 50mm concrete on metal lathor formed steel sheet, or40mm reinforcedgypsum-fibre concreteon 12.7mm gypsum wallboard

Roof Wood or steel joists 12.5mm plywood or Finish roofing materialand wood trusses 17mm T & G softwood with or without insulationSteel joists 50mm reinforced Finish roofing material

concrete or 50mm with or without insulationconcrete on metal lathor formed steel sheet, or40mm reinforcedgypsum-fibre concreteon 12.7mm gypsum wallboard

Source: Appendix D, 1995 NBCC, Table D-2.3.5.

Description of Membrane Fire-ResistanceRating, minutes

15.9mm Type X gypsum wallboard with at least 75mm 30mineral wool batt insulation above wallboard19mm gypsum-sand plaster on metal lath 30Double 14.0mm Douglas Fir plywood phenolic bonded 30Double 12.7mm Type X gypsum wallboard 4525mm gypsum-sand plaster on metal lath 45Double 15.9mm Type X gypsum wallboard 6032mm gypsum-sand plaster on metal lath 60

Source: Appendix D, 1995 NBCC, Table D-2.3.12.

protection provide all therequired fire-resistance rating.

NBCC Appendix D contains additional specific details onimportant features such as fastener spacing and minimumpenetration, as well as the orien-tation and joint support requiredfor gypsum wallboard panels.

[D-2.4.] CAM assigns fire-resistance ratings for solid-woodfloors, walls and roofs. This isuseful when dealing with exist-ing buildings with heavy timberconstruction elements.

[D-2.3.10.]and[D-2.3.11.] Tests showthat incorporating minor venti-lation openings in the ceiling

membrane does not significantlyreduce the fire-resistance ratingassigned to the assembly. In floorand roof assemblies assigned afire-resistance rating using CAM,duct openings are permitted inthe ceiling membranes providingsize, location, thermal protectionand other factors conform to therequirements in Appendix D.

[D-2.3.12.] Such openings are not allowed where the assignedfire-resistance rating of the floorassembly is derived entirely fromthe ceiling membrane.

Following are example applica-tions of the Component AdditiveMethod:


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Example 5.3Determine the fire-resistance rating of an interior partition with12.7mm Type X gypsum wallboard (GWB) on both sides of wood studs spaced at 400mm o.c. This assembly may be loadbearing or non-loadbearing.

From Table 5.2: ([D-2.3.4.A])

Time assigned to 12.7mm Type X GWB 25

From Table 5.3: ([D-2.3.4.C])

Time assigned to wood studs 20

Fire-resistance rating of interior partition: 45 minutes

38 x 89mm (minimum)Wood studs, 400mm o.c.(20 minutes)

1 layer 12.7mm Type Xgypsum wallboard(25 minutes)


Example 5.4Determine the fire-resistance rating of a wood stud exterior wallassembly with 15.9mm Type X gypsum wallboard on the interior sideand plywood sheathing and wood shingle siding on the exterior withthe studs spaced at 400mm o.c.

From Table 5.2: ([D-2.3.4.A])

Time assigned to 15.9mm Type X GWB 40

From Table 5.3: ([D-2.3.4.C])

Time assigned to wood studs 20

Fire-resistance rating of exterior wall: 60 minutes

[D-2.3.5.(2)] Mineral Fibre insulation having a mass of not less than 1.22kg/m2 of wall surface is required to be installed in stud cavities.

Notes to Example 5.4:

* If the wall cavity is insulated with Mineral Fibre insulation of rock fibres (not fibreglass) having a mass of not less than 1.22 kg/m2 of wall surface (15 minutes assigned contribution)Type X gypsum wallboard could be 12.7mm thick (25 minutes) and still retain 1 hour assignedfire-resistance rating.

** This combination could be replaced by any sheathing and exterior cladding.

** 7.5mm Exterior Grade plywood & wood shingle siding

38 x 89mm (minimum)Wood studs, 400mm o.c.(20 minutes)

* 1 layer 15.9mm Type Xgypsum wallboard(40 minutes)

Exterior (unexposed side)

Interior (fire side)


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Example 5.5Determine the fire-resistance rating of a wood truss floor assemblywith a ceiling of 15.9mm Type X gypsum wallboard and trusses spaced at 600mm o.c.

From Table 5.2: ([D-2.3.4.A])Time assigned to 15.9mm Type X gypsum wallboard 40

From Table 5.3: ([D-2.3.4.C])Time assigned to wood trusses 5

Fire-resistance rating of wood truss floor assembly: 45 minutes

Example 5.6Determine the fire-resistance rating of a wood joist floor assembly with aceiling of 2 layers of 15.9mm Type X gypsum wallboard and joists spacedat 400mm o.c.

Table 5.2 has only single layer applications or 15.9mm Type X for wood framingtherefore must use resistance of ceiling membrane only

From Table 5.5 ([TABLE[D-2.3.12]):Time assigned to two layers of 15.9mm 60Type X gypsum wallboard

Fire-resistance rating of wood joist floor assembly: 60 minutes

Notes to Example 5.6:* No openings would be permitted in the ceiling membrane.

1 layer of 15.9mm Type Xgypsum wallboard(40 minutes)

Wood truss600mm o.c.(5 minutes)

Finished wood flooring, resilient flooring,or ceramic tile & 12.7mm plywood or 17mmT & G softwood subflooring

Wood joists 400mm o.c.

Finished wood flooring, resilient flooring,or ceramic tile & 12.7mm plywood or 17mmT & G softwood subflooring

* 2 layers 15.9mmgypsum wallboard

FIRE AND SOUND RESISTANCE TABLES

]TABLES[A.9.10.3.1.A]and[A.9.10.3.1.B] .These tables contain sound trans-mission and fire-resistance ratingson typical wall and floor assembliesrespectively. These have beenchanged extensively in the 1995NBCC. This significant revision was precipitated by two importantfactors: • The 1990 NBCC increased the

minimum sound transmissionclassification (STC) ratingsrequired between residentialsuites from 45 to 50 andbetween suites and verticalshafts from 50 to 55.

• The CSA Standard, CSA A82.27-M1977 Gypsum Wall-board was changed to drop theminimum density require-ments for gypsum wallboard.As well, the definition of TypeX gypsum wallboard wasrevised from being based onperformance with loadbearingwood stud walls to being quali-fied on the basis of perfor-mance on a non-loadbearingsteel stud partition.

These changes to the CSA gypsumstandard raised questions as to theminimum performance expecta-tions for sound transmission andfire-resistance ratings on genericnew generation gypsum wallboardproducts for both ordinary andfire-rated boards.

Research ProjectA joint NRC/industry researchproject on the fire and sound performance of walls resulted ininformation on these new gypsum

wallboard products manufacturedto the new standard. A broaderlist of assemblies that could meetthe new minimum STC ratings in the NBCC was developed.

The project involved two studies,one on acoustical performance andthe other on fire resistance of wallassemblies. Complete wall systemswere tested to examine how theacoustic and fire performance wereaffected by the following:• resilient channel installation• type of insulation • type, density and thickness

of gypsum wallboard• stud type and arrangement

(single, staggered, double)

To develop information on ageneric basis for different wallassemblies, the assemblies weretested using:• minimum construction require-

ments in the Code such as fasteners spacing, location ofunbacked joints, lightweightordinary gypsum wallboard

• maximum design loads in thecase of loadbearing wood studwall assemblies

The resulting tables would thereforeapply to all wood stud wall systemsand non-loadbearing steel stud wallsystems that were constructed to therequirements of the NBCC.

In the fire-resistance portion ofthe project, loadbearing and non-loadbearing wood stud walls weretested with single, double andstaggered stud arrangements.Only non-loadbearing steel studsin a single row were tested.


For assessing acoustical perfor-mance, all of the forementionedassemblies and also loadbearingsteel stud systems were tested.

Research ResultsThe wall research project resultedin the following observations andconclusions:

Stud type and arrangement:In the non-load-bearing tests,wood stud assemblies provided a slightly better fire-resistancerating than steel stud assemblies.(load-bearing steel stud assem-blies were not tested for fire resistance).

Staggered studs and double rowsof wood studs on separate platesprovided significant increases inSTC without decreasing the fire-resistance rating.

Resilient channels:The use of resilient channels (RC)increased the STC.

Increasing the spacing of the RCincreased the sound rating overclosely spaced channels.

The use of RC under single layersof gypsum wallboard decreasedthe fire-resistance rating whilethe installation of the RC underdouble layers increased the fire-resistance rating.

Insulation:The installation of glass fibre orcellulose fibre insulation did notnegatively affect the fire-resistancerating when compared to an unin-sulated assembly.

The provision of mineral fibreinsulation increased the fire-resistance rating significantly.The tightness of the installationof these batts was a major contrib-utor to this increased rating.

Gypsum wallboard:The changes to the gypsum stan-dard permitting lower densities forregular gypsum wallboard had anadverse effect on the fire-resistancerating. Lower density gypsum wall-board had a lower fire-resistancerating than higher density gypsumwallboard. Ordinary gypsum wallboard with glass fibre in thecore had better fire performancethan the gypsum wallboard without glass fibre.

Two layers of gypsum wallboardsignificantly increased the fireresistance rating in comparisonwith single layer application.

Code Changes

[A-9.10.3.1.A] The results of theWall Project were used to develop anew Table A-9.10.3.1.A— Fire andSound Resistance of Walls in the1995 NBCC with a significantincrease in the number of listings.This allows designers much morechoice and flexibility in meetingthe requirements for fire and soundperformance set out by the NBCC.

Although Part 3 does not directlyreference Table A.9.10.3.1.A., thefire-resistance ratings listed weredetermined on the basis of testsconducted with the NBCC refer-enced fire standard, ULC-S101. Amajority of the listings are basedon actual tests while some of the


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values have been conservativelyextrapolated, especially the FRR's.

[A-9.10.3.1.B] The reduction in thefire-resistance rating of the gyp-sum wallboard manufactured tothe lower densities now permittedby the gypsum standard resultedin the removal of all reference toregular gypsum wallboard inTable A.9.10.3.1.B — Fire andSound Resistance of Floors. Floorand roof assemblies using onlyType X gypsum wallboard are ref-erenced in the 1995 NBCC.

CALCULATING FIRE RESISTANCEOF GLULAM TIMBERS

NBCC Appendix D also includesempirical equations for calculat-ing the fire-resistance rating of glue-laminated (glulam) timberbeams and columns, as well asconcrete and steel members. These equations were developedfrom theoretical predictions and validated by test results.

Large wood members have aninherent fire resistance because:• the slow burning rate of large

timbers, approximately 0.6mm/minute under standardfire test conditions

• the insulating effects of thechar layer which protects theunburned portion of the wood

These factors result in unprotectedmembers that can stay in place fora considerable time when exposedto fire. The NBCC recognizes thischaracteristic and allows unpro-tected wood members includingfloor and roof decks, which meetthe minimum sizes for heavy

timber to be used both where a 45minute fire-resistance rating isrequired and in many noncom-bustible buildings (Chapter 4).

[D-2.11.2.] Provisions for calculat-ing the fire-resistance rating ofglulam beams and columns arebased on data from tests on timberbeams and columns. This calcula-tion method determines a fire-resistance rating for beams andcolumns based on exposure to firefrom three or four sides. Using thisapproach, the fire-resistance rating(FRR) in minutes of glulam beamsand columns is

FRR = 0.1fB

for beams exposed to fire on 4 sides,

FRR = 0.1fB

for beams exposed to fire on 3 sides,

FRR = 0.1fB

for columns exposed to fire on 4 sides,

FRR = 0.1fB

for columns exposed to fire on 3 sides,

where

f = the load factor shown in Figure 5.13 to compensate for partial loading

B = the full dimension of the smaller side of the beam or column in mm before exposure to fire as shown in Figure 5.14

3B

2D−

3BD

−

4BD

−

4 2BD

−


D = the full dimension of the largerside of the beam or column in mm before exposure to fire asshown in Figure 5.14

The formula for columns or beamswhich may be exposed on threesides applies only when the unexposed face is the smaller sideof a column; no experimental dataexists to verify the formula when a larger side is unexposed. If a column is recessed into a wall or abeam into a floor, the full dimen-sions of the structural member areused in the formula for exposure tofire on three sides (Figure 5.14).

Comparisons of the calculatedfire-resistance ratings with

experimental results show thecalculated values are very oftenconservative. Some cases haveresulted in the fire-resistancebeing underestimated by almost30 percent. The predictions can be considered reasonably accurate.(see insert page 171)

A designer may determine the factored resistance for a beam or column by referring to CSAStandard CAN/CSA-O86.1-M94Engineering Design in Wood orthe 1995 Canadian Wood Council’sWood Design Manual.

An example of fire-resistance calculation of glulam beam isshown on the following page.

FIGURE 5.13

Load factor for glulam fire-resistancecalculations(NBCC, 1995)


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Load

fact

or, f

1.0

1.1

1.2

1.3

1.4

1.5

1.6

0

LSD Factored load5/Factored resistance, %25 50 75 100

Notes:1. Ke = Effective length factor2. L = Unsupported length of a column in mm3. B = Smaller side of a beam or column in mm (before fire exposure)4. LSD = Limit States Design5. In the case of beams, use factored bending moment in place of factored load.

Columns ≥ 12Ke L

B

and all beams

Columns < 12Ke L

B

FIGURE 5.14

Glulam exposure cases(NBCCAppendix D,1995)


B

D

Column

B

D

Column

Wall

B

DFloor

Beam

B

DBeam

Example 5.7:Determine the fire-resistance rating of a glulam beam exposed on threesides having dimensions of 175 x 380mm and with a factored bendingmoment equal to 80 percent of its bending moment resistance.

B = 175mmD = 380mm

From Figure 5.13, f = 1.075 for a beam designed to carry a factored load producing 80 percent of factored bending moment resistance.

t = 0.1fB

t = 0.1 x 1.075 x 175 x

Total fire-resistance rating = 66.6 minutes.

This beam could be used to support a one hour fire-resistance rated wood frame floor assembly such as the one shown in the Example 5.6 calculation earlier using the component additive method.

4175380

−

4BD

−

FIRE MODELLING

The use of computer fire endurancemodels is an alternative methodfor determining fire resistance andalso fire safety. As building codesthroughout the world move towarda performance-based approach and away from the prescriptiveapproach, fire models will becomean important tool for evaluatingthe safety of different systems.

These fire-endurance models arebased on:• the characterization of the

expected fire severity using a fire-growth model

• the determination of the heattransmission to the buildingelements using a heat transfermodel

• an evaluation of the strengthand deformation characteristicsof structural members at elevated temperatures using a modified structural model

Forintek Canada Corporation developed and is refining a fireendurance model. This model hasbeen verified and refined using datafrom the research that was used toproduce the new fire-resistance rat-ings for walls in Table A.9.10.3.1.A.


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Correlation of Calculation Methodand Fire Test

In December 1982, a glulamDouglas fir beam, with an actu-al size of 8-11/16 in. by 16-7/16 in. was tested in the US by theNational Forest ProductsAssociation (Now the AmericanForest and Paper Association)using the ASTM E-119 criteria.

Clear span of the beam = 16' 6-1/4".

Design span (including 1/2 of bear-ing length) = 203.625”

Loading:It was loaded at the centre andquarter span points with beamends restrained to prevent rotation.

Point load (live) = 6,436 lbs.

Uniformly distributed load (dead,self-weight) = 2.892 lbs/in

Moment = 670,256 in-lbs

Applied stress = 1713 psi

Allowable stress = 2396.5 psi

Applied/Allowable = 71.5%

Using the formulas fromAppendix D, the calculated fire-resistance rating of the beam isdetermined as follows:

F(applied load, allowable load) =F(1713, 2396.5) = 71.5 percent and f = 1.125 (from Figure 5.13).

Converting dimensions to metricvalues:

B = 220.7 mm,

D = 417.5 mm

R = 0.1 fB (4 - B/D)

= 0.1 (1.125) (220.7) (4 - (220.7/417.5))

= 86.2 minutes or 86 minutes 12 seconds.

Actual failure under fireendurance test: 86 minutes 15 seconds.

At the time of testing, the assemblies were equipped withadditional thermocouples anddeflection gauges to characterizethe heat transfer within andthrough the assemblies and theresultant structural response. This data is being used to validatethese new computer models.

For the time being, use of thesemodels is limited to researchersand skilled professionals in thefire protection field. Some modelshave already been used by fire protection professionals to showequivalent levels of safety. It islikely that expert systems willeventually be developed for use in design offices.

Studies on the pyrolosis and combustion of wood products aswell as the strength of wood atelevated temperatures is alsoleading to the development ofmodels that can calculate the fire-resistance rating of unprotectedwood assemblies. These modelspredict char depth, temperaturedistribution in the unburnedparts and strength properties ofwood at elevated temperatures.

The development, use and acceptance of computer modelswill give designers the flexibilitythat is not present in the currentsystem of prescribed require-ments. Changes to an assemblycould be evaluated by computerrather than having to perform afull scale fire-resistance testwhich can cost up to $20,000. Thiswill allow for more innovation inthe design and construction ofbuildings.

The NBCC is currently developingan objective based code with a target release date of 2001. Thiswould set performance objectivesthat buildings and building systems must meet. Computermodelling could then be used as a tool to evaluate systems againstthe performance criteria.

EXTRAPOLATION OF DATAFROM FIRE-RESISTANCE TESTS

Several documents have been written about extrapolation ofinformation from fire test results.Dr. Tibor Harmathy’s The TenRules of Fire Endurance providesguidance on the impact made on the fire-resistance rating ofmaterials and assemblies whenthe original product or assembly is altered in some way.

Harmathy’s document provides a means of assessing the fireendurance of various assembliessince it is impossible to test, priorto use, all assemblies used today.It was used to develop the NBCCComponent Additive Method inthe 1960s and to develop the val-ues listed in Table A-9.10.3.1.A.

Harmathy’s 10 rules are:Rule 1The thermal fire endurance of aconstruction consisting of a num-ber of parallel layers is greaterthan the sum of the thermal fireendurance characteristics of theindividual layers when exposedseparately to a fire.

Rule 2The fire endurance of a construc-tion does not decrease with theaddition of further layers.


Rule 3The fire endurance of construc-tions that contain continuous air gaps or cavities is greater than the fire endurance of similar constructions of the same weight, but containing no gaps or cavities.

Rule 4The farther an air gap or cavity islocated from the exposed surface,the more beneficial is its effect onfire endurance.

Rule 5The fire endurance of a construc-tion cannot be increased by increasing the thickness of a completely enclosed air layer.

Rule 6Layers of materials of low thermal conductivity are better utilized on the side of the construction on which fire is more likely to occur.

Rule 7The fire endurance of asymmetricalconstructions depends on thedirection of heat flow.

Rule 8The presence of moisture, if it does not result in explosivespalling, increases fire endurance.

Rule 9Load-supporting elements, such as beams, girders and joists, yieldhigher fire endurances when subjected to fire endurance testsas part of a floor, roof, or ceilingassembly than they would whentested separately.

Rule 10The load-supporting elements(such as beams, girders, joists) of a floor, roof or ceiling assembly can be replaced by such otherload-supporting elements that,when tested separately, yield fire-endurance ratings of not less than that of the assembly.

Figure 5.15 illustrates the 10rules. The rules are not intendedto replace more accurate designapproaches but may help in evaluating minor changes to thecomponents of tested assemblies.

A ULC publication, Criteria forUse in Extension of Data fromFire Endurance Tests (ULCSubject C263(e)-M1988) is based inpart on Harmathy’s rules. Basedon engineering evaluations, it dis-cusses how changes to an assemblyimpact its fire-resistance rating.

The impact of, for example, the addition of insulation in anassembly, a change in thickness of a protective wallboard, or theuse of different fasteners are alladdressed. The ULC document isuseful in determining whether or not an altered assembly can meetNBCC fire-resistance ratingrequirements.

A ULC task group is now draftinganother ULC document, which willprovide quantitative methods forcalculating fire resistance of struc-tures of all construction types. Athird ULC document will addressmethodologies that incorporatecomputer fire models for calculat-ing fire resistance empirically.


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FIGURE 5.15

Harmathy's tenrules of fireendurance


t12 > t1 + t2Rule 1

t2 > t1Rule 2

t2 > t1Rule 3

t2 > t1Rule 4

t1 ≈ t2Rule 5

t1 > t2Rule 6

t1 ≠ t2Rule 7

t1 > t2Rule 8

t1 > t2Rule 9

Beam A can be replaced by Beam B if t2 > t1Rule 10

For the floor assembly For a beam when tested separately

Beam tested as part of the floor Beam tested separately

Fire

Fire FireFire Fire

A B

t = Fire Endurance

t12t1 t2 t1 t2 t1 t2 t1 t2

t1 t2 t1 t2 t1 t2 t1 t2

Fire

t1 t2

t1 t2

High ConductivityLow Conductivity

Dry

MoistHighConductivity

LowConductivity

HISTORY

Minimum fire-resistance ratingsfor the major structural assem-blies of a building, as specified in Chapter 3.2 of the NBCC, werepartly determined on the basis of Ingberg’s fire load conceptdeveloped in the 1920s.

Ingberg’s theory is based on:• the length of time required

for a real fire to consume allcombustible contents within afloor area and the maximumtemperatures reached in a fire(time-temperature curve)

• the severity of a real fire beingequal to that of the standardfire exposure over a specifiedtime if the area under thecurve representing thetime/temperature history of a real fire were equal to thatunder the standard time/temperature curve

In the case shown, (Figure 5.16)the area under the time-tempera-ture curve for the real fire isequal to the area under the standard fire test at 45 minutes.Therefore, the real fire is seen tobe equivalent to an exposure of 45 minutes in the standard firetest. Based on Ingberg’s approach,a 45-minute fire-resistance ratingshould be provided for an assem-bly enclosing a fire compartmentin a building containing the occupancy represented by the fire exposure in Curve B.

Ingberg used the fire load or combustible content to developthe expected time/temperaturecurves (fire severity). The areaunder these curves were then compared to the area under thestandard time temperature curveand fire-severity equivalents were assigned to various fire loads (Table 5.7).

Fire-Resistance Rating Requirements in the NBCC 175

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5.5 Fire-Resistance Rating Requirements in the NBCC

FIGURE 5.16

Ingberg’shypothesis on equal fireseverities

Standard Fire

Actual Fire

Baseline

Time

Tem

pera

ture

A

B

TATS 45 min

This approach was among the factors considered in the develop-ment of NBCC’s minimum fire-resistance rating requirements.Other critical factors includedprovisions for firefighting, exitcapabilities, building size andinterior fire protection.

The rule of thumb approach onwhich most model building codesare based today has been underreview for the past 30 years. Closerconsideration is now being given tofactors, aside from fire load, whichare known to affect fire severitysuch as: • compartment ventilation• thermal characteristics of

compartment linings• area of compartment boundaries• compartment height.

The NBCC is currently preparingan objective based code for 2001.With the desired objective, orlevel of safety, specified, designerscan use empirical and theoreticalcalculations to estimate the levelof safety provided by a buildingsystem. These calculations takeaccount of expected fire severity,heat transmission in building elements and the strength anddeformation characteristics ofstructural members at elevatedtemperatures.

These more sophisticated calcula-tions would probably involve somecomputer modelling (Section 5.4).It is currently the intention tohave the new code also show pre-scriptive solutions that will bedeemed to meet these objectives so that every building will notrequire modelling to determinethe construction requirements.The current prescriptive require-ments described in the 1995 NBCC will form the basis of these prescriptive alternatives.

As with other design procedures,the user must fully understand theunderlying assumptions and limita-tions which affect these importantfactors if the values are to be trulyrepresentative of the design in question. Reference Numbers 5, 7, 8,10, 11, 21, and 41 in the Appendixprovide more detailed informationon the various engineered designmethods for fire safety.

FIRE-RESISTANCE RATING REQUIREMENTS FOR STRUCTURAL ASSEMBLIES

The difference between fire sepa-ration and fire-resistance ratingis very important. A buildingcomponent such as a column mayrequire a fire-resistance ratingbut it is not a fire separation.

TABLE 5.6

Fire severitybased on fireload concept


Fire Load of Occupancy Fuel Load Equivalent Fire Severitykg/m2 (lb/ft2) Mj/m2 (BTUs/ft2) (Standard T/T Curve), minutes24.4 (5) 456 (40,000) 3048.8 (10) 912 (80,000) 6073.2 (15) 1368 (120,000) 9097.6 (20) 1824 (160,000) 120146.5 (30) 2736 (240,000) 180

In this respect, the definition offire-resistance rating might bemisinterpreted as it refers to thepassage of flame and the trans-mission of heat. Obviously, in the case of a column or beam, theapplicable criteria is its ability to sustain the applied load for the specified time.

[3.2.2.53.] An assembly, such as a wall or a floor can also berequired to be built as a fire separation but may not require a fire-resistance rating. For example, in office buildings threestoreys or less in building height,the NBCC permits floor, mezza-nine and roof assemblies to be:• unrated noncombustible

construction, • combustible construction

with a 45-minute fire-resistance rating, or

• heavy timber construction

However, floor assemblies in thiscase must be built as fire separa-tions regardless of constructiontype. Therefore, a floor assembly ofnoncombustible construction wouldhave to be constructed as a fire separation but would not have arequired fire-resistance rating.

The rationale for when to specifythe 45-minute fire-resistance ratingfor combustible construction and towaive this requirement for noncom-bustible assemblies was developedin the 1960s. This was based on theconcept that structural stabilityunder fire conditions and com-bustibility characteristics of thestructure equate the two types ofconstruction from a fire safetystandpoint.

In simple terms, it was suggestedthat wood-frame construction with a45-minute fire-resistance rating canbe expected during a fire to be:• structurally stable (1 plus), but, • perceived as representing fuel

load capable of contributing tothe fire severity (1 minus)

On the other hand, unrated noncombustible construction was considered to be:• non-fuel contributing (1 plus),

but,• with exposed steel supports,

expected to be unstable (1 minus)

Simply adding these pluses andminuses, the two types of construc-tion were considered equal andconsequently a number of Articlesin Subsection 3.2.2. of the NBCCpermit either type to be used incertain size buildings (DesignRequirement Tables in Chapter 4).

Although this approach has beenaccepted for years, with no appar-ent negative impact on fire safety,the principle of equating the twodifferent types of constructionfrom a fire safety standpoint isquestionable.

Unprotected noncombustible construction collapses early in the standard fire-resistance test,usually within 10 minutes. A combustible assembly with a 45-minute fire-resistance ratingstays in place for the duration ofthe test. Any fuel contributionfrom the combustible assembly is minimal during the test andoccurs typically at the end of the test period.


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In a real fire, assembly stabilityis critical in ensuring occupantstime to evacuate. The impact ofany fuel contribution from thestructure on the severity of a firein a room is expected to be mini-mal and should occur after theoccupants have left the building.

Today’s trend to develop less prescriptive- and more perfor-mance-based building codes isexpected to have an impact on thistraditional approach of equatingthe two types of construction. Ascode objectives are determined, thequestion of whether unprotectednoncombustible construction pro-vides an equivalent level of safetyas rated combustible constructionwill have to be addressed. The factthat most fire casualties areattributed to fire severity andsmoke caused by burning contentsand are not related to buildingconstruction type must be takeninto consideration.

FLOOR ASSEMBLIES INRESIDENTIAL OCCUPANCIES

In certain small buildings, majorstructural assemblies such asfloors and roofs need not be pro-tected nor rated; however, they areexpected to possess an inherentdegree of fire-resistance, adequateto ensure occupant safety wherecomplete building evacuationrequires only a few minutes.

[3.2.2.47.] This is the case insmaller residential buildings, suchas row housing. Floors within eachdwelling unit, including the floorassembly over a basement, need notbe constructed as fire separations

and do not require a fire-resistancerating (Figure 5.17).

If this were not permitted, the floorassemblies would have to be fireseparations which is impractical.As a fire separation, all penetra-tions through the floor assemblywithin the individual dwellingunit, including the stairways,would have to be protected.

In such Group C buildings, however, floor assemblies must be constructed so that the fire sep-arations between dwelling units is maintained. For wood-frame construction, how the joists are run relative to the wall will affectthe protection features needed tomaintain the continuity of the ver-tical fire separation. (Figure 5.18).

In small residential buildings withmulti-storey dwelling units stackedabove one another, floors within theunits need not be constructed asfire separations but must have afire-resistance rating. This meanscontinuity is not required butfloors must be built to stay in placelonger during a fire. With onedwelling unit above another, struc-tural stability is more critical as itcould take longer for upper unitoccupants to become aware of a firebelow and evacuate the building.

Occupants both within the unitand in the adjacent units faceincreased risk when unit floors arenot constructed as fire separationswith a fire-resistance rating.These risks are:• the potential for early collapse

of assemblies within the units


• the spread of smoke and hotfire gases from floor to floorwithin the unit.

[3.3.4.2.] Because of these poten-tial hazards, limitations are placedon buildings constructed with floorassemblies not designed as fire separations (Figure 5.17).The vertical travel distance fromthe lower floor to the uppermostfloor within the unit is limitedto 6m. The minimum fire-resistance rat-ing required for the fire separationsbetween the individual dwellingunits and the remainder of thebuilding is determined by thebuilding height and the provisionof sprinklers. If the building isunsprinklered or more than threestoreys in height, the fire separa-tions must have a one hour fireresistance rating.

A fire-resistance rating of 45minutes is required for the fireseparations in sprinklered build-ings less than 4 storeys in height.

FIRE-RESISTANCE RATING REQUIREMENTS OF LOADBEARING STRUCTURAL ELEMENTS

[3.1.7.5.] In most cases, loadbearingstructural elements such ascolumns, walls and arches musthave a fire-resistance rating at leastequal to the rating required for thefloor, roof or mezzanine assemblybeing supported. This requirementmaintains the structural stability of the fire compartments formedwithin a building.

This is logical; to have a two-hourrated floor supported by unprotectedsteel columns that might collapse assoon as 10 minutes after flashover inthe compartment below would makelittle sense.

FIGURE 5.17

Fire separations in residentialoccupancies


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6mmax

Notes:1. All units need to be separated from each other by fire separations having a fire-resistance rating of 1 hour.2. Floor assemblies in Units A and B need not be fire separations or have a fire-resistance rating.3. Floor assemblies within Units C and D need not be fire separations but must have a fire-resistance rating of at least 45 minutes.

A B C

D

FIGURE 5.18

Continuity offire separations


19 x 89mm tongueand groove

finished flooron 12.5mm

plywood subfloor

12.7mm gypsum wallboard

38 x 235mm joists

2 layers of blocking

1 layer of 15.9mmType X gypsum wallboard

on 38 x 89mm studsat 400mm centres

60-minutefire-resistance rating

Plan

Section A-A

AA

Note: The two layers of blocking are required when joists are parallel or perpendicular to the wall.

Firestop

An exception to this generalrequirement permits the use ofmixed types of construction, withunrated noncombustible con-struction and 45 minute rated combustible construction for some buildings (Figure 5.19)which are typically limited insize. Articles 3.2.2.21. to 3.2.2.81.specify where these mixed types of construction are permitted andwhen the loadbearing elements donot need a fire-resistance rating.

In these instances of mixed construction, a wood roof assemblywould require a 45-minute fire-resistance rating or heavy timberconstruction. If the roof is built ofunprotected steel, no rating isrequired. A wood-frame wall sys-tem supporting any of the threetypes of roof would have to have

a fire-resistance rating of 45 min-utes but an unrated steel columncould also be used. A heavy timbercolumn and beam arrangementsupporting any of the roofs wouldhave to conform to the NBCCminimum sizes.

These provisions permit the use ofunrated noncombustible supportsto support a rated wood-frameassembly. These are partly basedon the plus and minus point scoring system (discussed in theprevious section) equating allthree construction types from afire safety standpoint. The appar-ent inconsistency of supportingrated construction with unratedsupports is being questionedtoday. These anomalies will beexamined with the move towardperformance-based requirementsin building codes.

FIGURE 5.19

Mixed construction:wood trusseson heavy timbers onsteel columns


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[3.1.7.4.] If a designer selects abuilding assembly with a fire-resistance rating exceeding NBCCminimum requirements, there is no obligation to provide anequivalent level of fire protectionfor the remainder of the building.The NBCC states that the sup-porting construction must have a fire-resistance rating not lessthan the minimum fire-resistancerating required.

If a 45-minute rating is requiredand the designer selects a one-hour rated floor assembly, thesupporting construction for theassembly is only required to have a 45-minute rating. If mixed types of construction,unrated noncombustible or ratedcombustible, are permitted, the supports for this one-hourassembly would also be permittedto be heavy timber, or unprotectednoncombustible construction.

Other exceptions to fire-resistancerating requirements of supportingconstruction deal with a vaultconcept. Extra fire-resistance maybe necessary to contain either ahigh-hazard occupancy within aportion of a building or to protectvaluable records from exposure tofire in the surrounding floor area.In such cases, it is not considerednecessary to upgrade the fire-resistance rating of the building’sstructural frame supporting theseadditionally protected assemblies.

EXCEPTIONS TO FIRE-RESISTANCE RATING REQUIREMENTS

[3.2.2.3.(1)] Fire protection is notrequired for:• steel components such as lintels,

exterior support members forbalconies and shelf angles

• steel members in protected exitstairways

• steel framework around shaftdoorways and for the support ofelevator guides (provided theircollapse would not affect thebuilding structure)

[3.2.2.3.(1)(g)] Steel members andstructural concrete members forexterior use on certain buildingsdo not require fire protection ifthey meet the following criteria:• buildings must be four storeys

or less in building height • occupancy must not be Group E

or Group F, Division 1 and 2• must be located at least 3m

from the property line [(3.2.3.8.)]• unprotected members have to

be at least 1m away fromunprotected openings in theexterior wall

• where the distance between theexterior unprotected member andthe wall is less than 1m, adequateshielding must be provided froma fire inside the building


This applies primarily to exteriorcolumns but could include exteri-or beams and other members.These exceptions allow design andarchitectural flexibility. The concept is a result of US andBritish research. The exception is not permitted for Group E and Group F, Division 1 and 2occupancies as the fire load normally contained in thesebuildings is relatively high andmore severe fires can be expected.

These unprotected members must be placed outside exterior wallsalthough part of the member may beenclosed by the wall. They must belocated at least 3m from the prop-erty line to guard against exposurefrom fire on adjoining properties.

Unprotected members have to be atleast 1m away from unprotectedopenings in the exterior wall. Thisis required so that a fire in thebuilding will not unduly expose themember to high radiation levels.

Where the distance between theexterior unprotected member andthe wall is less than 1m, the NBCCrequires adequate shielding fromfire inside the building. Thisshielding is usually provided bythe exterior wall adjacent to themember. The wall must have a fire-resistance rating at least equal tothat required for the member hadit been designed for use within thebuilding.

The purpose of this shielding is to provide protection from radiantheat from a fire within the build-ing. To provide this protection, the wall (or other shielding) mustextend on either side of the mem-ber for a distance at least equal tothe distance between the outsideface of the wall and the outsideface of the member (Figure 5.20).The exterior shielding wallshould be constructed as if it werea fire separation without open-ings for the required distance.

FIGURE 5.20

Exceptions for exteriorunprotectedmembers


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Property line

Unprotected steel column

Exterior wall usedas sheilding

y y

x z

3mmin.

Building Interior

Notes:1. If distance “x” is 1 m or more no column protection is required, except for conditions in note 3.2. If distance “x” is less than 1 m, distance “y” must be equal to or greater than distance “z” and sheilding must have a fire-resistance rating equal to that required for interior columns (or the exterior column be equally protected)3. If the building is Group E (Mercantile) or Group F, Divisions 1 or 2 (Industrial), sheilding or rating of the element is required regardless of the distance “x”.

Window

[3.2.8.1.(1)] The NBCC generallyrequires that floor area sectionswhich do not terminate at an outside wall, a firewall or a vertical shaft, terminate at a vertical fire separation with thesame fire-resistance rating as thefloor assembly. In circumstanceswhere this is impractical, such astheatre balconies or mezzaninesin a curling rink or other arenatype buildings where an unob-structed view of the floor below is necessary, the NBCC waives the fire separation requirements.

[3.2.8.2.(1)] Mezzanines which are not considered as storeys indetermining building height (Chapter 4) are also exempt.However, modern buildings ofteninclude large interior spaces, usually at entrance level, that aremore than one storey and thusconnect the overlooking floors ormezzanines. These atriums, theNBCC more broadly terms “inter-connected floor spaces", includefloors connected by escalators,moving walkways or architecturalstairways where the opening inthe floor above is not enclosed.

Interconnected floor spaces warrant specific requirementsbecause they violate the basicprinciple of compartmentation.These interconnected floor spacespresent the following risks:

• fire could progress rapidlybetween levels of the structure,which lacks barriers to preventsmoke simultaneously contami-nating all open levels of thebuilding

• occupants may be preventedfrom evacuating the buildingbefore being overcome by heator smoke, since all levels haveto exit at once

• major structural componentscould be exposed to a prolongedfire condition, since no barriersexist to resist fire spread

• fire-fighters who traditionallyuse the floor beneath a firefloor as a staging area could be impeded

[3.2.8.] In the majority of cases, a building containing an inter-connected floor space must meetthe following requirements:

• construction must be of noncombustible or heavy timber construction [3.2.8.3.]

• the building must be sprinklered [3.2.8.4.]

• vestibules must be provided for exits and for elevators opening into the space [3.2.8.5.]

• occupants must be protected by cumulative exits, where all occupants on all floors canenter the stairs simultaneously,[3.4.3.3.(2)] , or

• 0.3m2 of treads and landingsper person must be provided inthe exit stairs, which gives aholding area that all occupantscan enter but where they mustwait to move to the outside, or

• instead of this holding area, aprotected floor space of 0.5m2 perperson must be provided [3.4.3.3.]

Fire Protection Requirements for Mezzanines and Atriums 185

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5.6 Fire Protection Requirements for Mezzanines and Atriums

[3.2.8.6.] The protected floorspace must be separated from the interconnected floor space byfire-rated construction. Occupantscan leave the interconnected floorspace and use the protected floorspace as a waiting area beforeevacuation by stairs serving thisspace (Figure 5.21). Occupantsmust not have to re-enter theinterconnected floor space in order to exit the building.

[3.2.8.7.] Most buildings contain-ing an interconnected floor spacerequire sprinklers to be installedthroughout all portions of thebuilding. Close-spaced sprinklersand draft stops must be providedaround all but the largest of openings, just as for escalators.The draft stops provide a reservoirfor products of combustion belowthe ceiling level intended to pre-vent smoke from spilling directly

into the open space; the heatbuild-up also ensures faster activation of sprinklers. Draftstops must be provided in largerinterconnected floor spaces evenwhen the close-spaced sprinklersare not required by StandardNFPA 13, Installation ofSprinkler Systems.

[3.2.4.11.(1)(f)] As well, smoke detectors must be located in thevicinity of the openings close tothe draft stops.

[3.2.4.7.[&[3.2.4.9.] In the 1995NBCC, all sprinkler systems inbuildings must be fully supervisedand be arranged to transmit a signalto the fire department.

[3.2.8.8.] A mechanical exhaustsystem must be provided to clearsmoke from the open intercon-nected floor space. This is a

FIGURE 5.21

Typical atriumsand exits


Exit

Elevators

Exit

VestibuleProtected

floor space

Openspace

Exit

Typical plan of floor in atrium

Note:Distance to closest exit vestibuledoor from any point on any atrium must not exceed 45m

9th floor

8th

7th

6th

5th

4th

3rd

2nd floor

Atrium

Typical section

Atrium

Grade

manual system, not an automaticsmoke control system as requiredfor high-rise buildings ( Chapter10).

[3.2.8.9.] Sprinklers situatedhigh above the floor of an inter-connected floor space may notrespond quickly enough to a fire.For this reason, the quantity ofcombustible materials, (except forinterior finishes), permitted inthose parts of the interconnectedfloor space where the ceiling ismore than 8m above the floor, is limited to 16 grams per cubic metre of volume of theinterconnected floor space.

[3.2.8.2.(5)] For buildings contain-ing smaller interconnected floorspaces, the requirements statedabove are not required provided:

• the opening is used for escala-tors or inclined moving walks

• each opening does not exceed10m2

• the building is sprinklered

• the interconnected floor spacecontains only Group A,Division 1, 2 or 3, Group D or Group E occupancies

[3.2.8.2.(6)] Buildings containinglarger interconnected floor spacesdo not have to meet the construc-tion and fire safety requirementsstated previously if the followingconditions are met:

• the interconnected floor spaceconsists only of the first storeyand the storey above or below it

• the openings are used for stair-ways, escalators or movingwalks or the interconnectedfloor space is sprinklered

• the interconnected floor spacecontains only Group A,Division 1, 2, or 3, Group D, E or Group F, Division 3 majoroccupancies

• the building area is not morethan half the building areapermitted in NBCC Subsection3.2.2

Fire Protection Requirements for Mezzanines and Atriums 187

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[3.1.11.1.] Normal framing methodsin construction leave voids betweenmembers and membranes on eachside of a wall. If these voids run theheight of the building or connectwith those in a ceiling space, hotgases and flames can spread farfrom the area of fire origin by airmovement within these spaces. TheNBCC therefore requires blocks ofsolid construction at regular inter-vals in all concealed spaces. Firestopping is a good practice in bothcombustible and noncombustibleconstruction.

[3.1.11.7.] Fire stopping restrictsthe passage of flames, hot gasesand smoke. Fire stops can be made of:

• 38mm lumber or two layers of 19mm lumber

• plywood, waferboard or oriented strandboard (OSB) notless than 12.5mm thick fordeeper spaces such as attics

• 12.7mm gypsum wallboard

• 0.38mm sheet steel

• any material which remains inplace and restricts the passageof flames when subjected to the standard fire exposure ofCAN/ULC-S101-M

The NBCC specifies type, thicknessand location of fire-stop materials.The requirements give maximumdimensions, horizontally and verti-

cally, depending on the concealedspace and on the surface flame-spread rating of the materials within the space. Figures 5.22 to 5.26illustrate typical fire stopping.

[3.1.11.5.] Restrictions on thesize of fire stopped compartmentsare eased when exposed materialswithin have a flame-spread rating of not more than 25. Thematerials within the space willnot contribute significantly tofire intensity.

For example, in roof spaces or atticsof combustible construction, firestopping is required to separate theconcealed space into compartmentsnot more than:

• 300m2 in area with no dimensionmore than 20m if the exposedconstruction materials have aflame spread rating more than 25

• 600m2 in area with no dimen-sion more than 60m if exposedconstruction materials have aflame spread rating not morethan 25

There are no restrictions on com-partment size if it is protected byautomatic sprinklers.

Fire Stops 189

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5.7 Fire Stops

FIGURE 5.22

Wood-framefire stopping


Ground FloorExterior Wall

Ground FloorInterior Wall

Multiple Storey FloorsExterior Wall

Multiple Storey FloorsInterior Wall

Fire stopping

Fire stopping

Fire stopping

Fire stopping

Fire stopping

Fire stopping

Fire Stops 191

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FIGURE 5.23

Wood-framefire stopping

FIGURE 5.24

Furring as firestopping

FIGURE 5.25

Stair fire stopping

Fire stopping

Coved ceiling space

Fire stopping

Fire stopping

Wood nailing element

Insulation

Fire stopping

FIGURE 5.26

Plywood asattic fire stopping

[3.2.3.15.] The foregoing limitswill often permit an attic or roofspace to extend across more thantwo residential suites or morethan two patient sleeping roomsin occupancies such as nursinghomes. In such cases, fire stoppingmust isolate the attic or roof spacefrom eave projections or roof over-hang. The firestops are necessaryto prevent flames projecting froman opening (window or door) in theexterior wall below the soffit fromentering the roof space throughvent openings in the soffit.

This additional fire stopping isnot required when:

• the soffit is protected over thefull width of the opening andover a distance extending 1.2mfrom the sides of the opening by noncombustible material, plywood, waferboard, orientedstrandboard (OSB) or lumberwith a minimum thicknessdepending on the material used (Chapter 7)

• the fire compartments behindthe window or door openings aresprinklered.


The provision of automatic sprinklers in a building or floor area will in many instancesrelax the NBCC fire-protectionrequirements. The underlyingprinciple is that a sprinkler system provides a level of firesafety at least equal to that of an unsprinklered building withpassive fire protection require-ments in place.

The NBCC Standing Committeeson Fire Protection and Occupancyexamined the benefits of sprin-klers and also what fire safetyrequirements could be changed toproduce an equivalent level ofsafety when the building is sprin-klered. This review resulted inthe requirement of mandatory

sprinklers in many more occupan-cies (Table 4.3). The review alsoresulted in an increase in the sizeof buildings permitted to be con-structed of wood if they are sprin-klered. The spatial separationrequirements for sprinkleredbuildings have also been reduced.In light of these new provisions,all sprinkler systems must beelectrically supervised and theiractivation must transmit a signalto the fire department.

Sprinkler installation costs canbe weighed against savings result-ing from their use, either in theform of reduced construction costsor reduced insurance premiumsfor the building. An automaticsprinkler system properly

FIGURE 5.27

Sprinklers allowuse of heavytimber roofassemblies in large non-combustiblebuildings

Sprinkler Alternatives 193

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5.8 Sprinkler Alternatives

installed and maintained ensuresa high level of fire safety for occupants at all times.

Automatic sprinklers have adirect impact on fire protectionrequirements in several areas:

• The area or height of a buildingcan be increased withoutincreasing the level of fire resis-tance or changing constructiontype to that otherwise requiredfor the larger sized building (Chapter 4).

• The maximum size of openingspermitted in a fire separation can be doubled. [3.1.8.6.]

• Combustible sprinkler piping is permitted if compartments onboth sides of a fire separation are sprinklered. [3.1.9.4.]

• Compartments between firestops in sprinklered roof spacescan be enlarged or in some casesfire stops can be omitted.[3.1.11.5.]

• A heavy timber roof assembly can be used in all sprinkleredbuildings up to two storeys inbuilding height without a limiton building area (Figure 5.27)[3.2.2.16.].

• The fire-resistance rating forroof assemblies is waived forall sprinklered buildings.

[3.1.4.6.] This last item expandsopportunities for the use ofexposed unrated wood-frame roof assemblies especially in non-residential applications(warehouses, schools, retail stores).In this case, if glulam or solidsawn timber elements or solidwood roof decks are used, theheavy timber minimum sizingrequirements would not apply.

Minimum size specifications forheavy timber components wouldstill apply when a heavy timberroof assembly is used in a sprin-klered noncombustible buildingof two storeys or less. However, nofire-resistance rating would berequired for the roof assembly.

[3.1.7.5.] By waiving the fire-resistance ratings for roofs, theroof ’s loadbearing support ele-ments such as columns or walls are also exempt from ratings.


Chapter SummaryCompartmentation and structural integrity are two of themost important basic principles of fire safety on which theNBCC requirements are based. These principles satisfy bothbranches of Contain Fire by Construction in the NFPA Fire Safety Concepts Tree (Chapter 3).

The weakest parts in fire separations are the openings provided for people and building services. Special attentionmust be given to these openings if fire separations are toserve their purpose. Increased hazards created by intercon-nected floor spaces also merit additional NBCC specifica-tions. Code requirements for buildings with interconnectedfloor spaces provide for a level of safety similar to that possible with floor-to-floor separations.

Sprinklers are a viable alternative fire protection measure.Many fire-resistance and fire separation requirements arerelaxed when automatic sprinklers are used because they can keep a fire under control until the firefighters arrive. In general, NBCC requirements combine the need for passive(compartmentation) and active (sprinkler and fire alarm) fireprotection systems in buildings to ensure that the structureand the occupants will be adequately protected from fire.

Sprinkler Alternatives 195

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6Flame Spreadof Materials6.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

6.2 Determining Flammability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

The “Tunnel” Fire-Test Method for Interior Finishes . . . . . . . . . . 201

Flame-Spread Ratings of Foam Plastics and

Other Anomalous Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

Alternative Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

6.3 Interior Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

Paint and Wall Coverings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

Flooring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Light Diffusers and Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Application of NBCC Requirements . . . . . . . . . . . . . . . . . . . . . .209

6.4 Fire-Retardant Treated Wood . . . . . . . . . . . . . . . . . . . . . . . . . 213

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

Flame-Spread Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

Exterior Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

Fire-Retardant Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

6.5 Roof Assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

Fire-Retardant Treated Wood Roof Systems . . . . . . . . . . . . . . 218

Roof Coverings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

Chapters 4 and 5 concentrated onthe Contain Fire by Constructionbranch of the Manage Fire objectiveof the NFPA Fire Safety ConceptsTree introduced in Chapter 3. Theconstruction methods or systemswhich create barriers to the spreadof fire throughout a building wereexamined.

Once a fire is started, however, therate at which it grows has a signifi-cant impact on the safety of theoccupants and the time availablefor their escape. This dependslargely on the flammability ofbuilding contents and materials.This concept is expressed by theControl Fuel branch of the ManageFire objective.

In an attempt to control the fuelpresent, the NBCC restricts thesurface flammability of:• all interior finishes in buildings

• materials contained withinconcealed spaces

• materials used in roof assemblies

This chapter explains the fire testprocedure used for determiningflame-spread ratings for buildingmaterials. Alternative flame-spread rating values for genericproducts are listed as are valuesfor common wood species.

The principles underlying theminimum requirements of theNBCC are discussed. Many woodproducts can be used as finishesthroughout buildings withoutfire-retardant treatments.

Fire-retardant treated wood, a special type of wood finish, isdiscussed along with the NBCCrequirements for roof assembliesand roof coverings.

In Group A,Division 2 occupancies,walls and ceiling finishes with a FlameSpread Rating of up to 150 arepermitted.


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THE “TUNNEL” FIRE-TESTMETHOD FOR INTERIOR FINISHES

As indicated in Chapter 3, flamma-bility is the property of a materialto burn more or less quickly.

The need to control the flamma-bility of building content andtheir materials was highlightedby a number of major fires, mostlyin the 1940s and 1950s, whichresulted in extensive loss of lifeand property.

In the Cocoanut Grove fire in 1942,for example, it was estimated thatthe fabric of the ceiling decorationin the room where the fire origi-nated had a flammability in excessof 16 times what is permitted todayby the NBCC.

The rapid and uncontrolled spreadof fire in many other instancessuch as the Winecoff Hotel,LaSalle Hotel and St. AnthonyHospital fires was clearly relatedto the rapidity of flame spread onthe interior finish (Chapter 1).Asphyxiation was also the cause ofmany fatalities.

This prompted regulatory authori-ties to determine means of classify-ing materials in accordance with atleast two essential fire properties:• surface flame spread• smoke developed

The fire-test method which hasbeen used for the last 30 years to determine these propertieswas devised by A. Steiner atUnderwriters' Laboratories Inc.in the United States.

FIGURE 6.1

The Steiner tunnel for measuring surface burningcharacteristics

Determining Flammability 201

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6.2 Determining Flammability

[3.1.12.1.] In Canada, it is describedin the standard published byUnderwriters' Laboratories ofCanada, CAN/ULC-S102, StandardMethod of Test for Surface BurningCharacteristics of BuildingMaterials and Assemblies.

The fire-test method provides a relative assessment of the surfaceburning characteristics of materi-als. The sustained flaming combus-tion which occurs at the surface of amaterial is measured. Flaming onmost materials progresses along thesurface as additional volatiles arereleased and mixed with the oxygenfrom the heated area immediatelyadjacent to the flaming area.

The test furnace is usually referredto as “the Steiner tunnel” or just“the tunnel” because of its shape; itconsists of a rectangular duct 7.6mlong, 450mm wide and 300mm deep(Figure 6.1).

The walls and floor of the tunnelare constructed of refractory brick,except for a row of glazed ports usedfor viewing. These windows extendthe length of the chamber on oneside. The tunnel has a noncom-bustible, full-length airtight lidwhich can be removed to positionthe test specimen sample along thetop of the furnace.

For most materials, the test speci-men is installed on the ceiling ofthe tunnel. At one end of the tunnel,gas burners produce a flame with asteady heat release that impingesdirectly on the test specimen. Asteady draft of air lightly fans theflames toward the other end.

The test lasts 10 minutes for mate-rials commonly used for interiorfinishes. The distance traveled bythe flame front is observed throughthe viewing ports and recordedagainst time.

The test results provide a relativeassessment of the flammability ofmaterials. The flame spread mea-sured on a specific product is eval-uated against two products whichserve to calibrate the apparatus:

• inorganic reinforced cementboard assigned a flame-spreadrating of 0

• red oak assigned a flame-spread rating of 100

When a noncombustible materialsuch as inorganic reinforcedcement board is tested, the flamesfrom the burners, forced towardsthe other end of the tunnel by the flow of air, will extendapproximately 1370mm, and willnot progress beyond that point.

With select red oak flooring, theflame will continue to advancetowards the end of the tunnel,7.6m away, which it reaches inapproximately 5.5 minutes.

At the vent end of the tunnel, a photo-electric device measuresthe opacity (density) of the smoke.This provides an indication of theamount of smoke released fromthe burning material. This is particularly important in the case of certain types of materialswhich can release substantialamounts of smoke without havinga high degree of flammability.


All tested materials are comparedto these two reference materialsand the results of the tests providewhat is termed the flame-spreadrating (FSR) and the smoke devel-oped classification (SDC).

[3.1.12.1.(1)] Because there is usually some degree of variationin test results, the NBCC requiresthat the flame-spread rating andsmoke developed classification bedetermined from the average of atleast three tests for each material.

Not all materials react in the sameway under the test. For example, intesting gypsum wallboard, theflame front typically advances forthe first two minutes and thenrecedes. In the case of loose-fill cel-lulose insulation, the flame frontfirst advances, then recedes andadvances again.

To account for these differentreactions and to obtain a moreuniform ranking of materials, thelatest edition of the CAN/ULC-S102 uses formulae (developed by George Williams-Leir) to normalize test results. The formulae are given in Appendix 2of the ULC standard.

FLAME SPREAD RATINGS OFFOAM PLASTICS AND OTHERANOMALOUS MATERIALS

If a building material is intendedto be used as a finished floor sur-face, testing on the ceiling of thetunnel will not be representativeof end use conditions. In addition,the material might react quite differently with flames impingingon it in an upside down position.

Certain materials tend to dripand melt, or sag under their ownweight when exposed to a firesource. Tests on the tunnel ceilingof these materials could result insome anomalies if the materialmelted or dropped down and awayfrom the fire source.

[3.1.12.1.(2)] The NBCC requiressuch materials (when regulated)be tested in accordance with ULC standard CAN/ULC-S102.2,Standard Method of Test forSurface Burning Characteristicsof Flooring, Floor Covering, andMiscellaneous Materials andAssemblies.

In this test, the samples areplaced on the floor of the tunneland the burner gas ports areturned downward. The same formulae used in normalizing testresults for the CAN/ULC-S102standard are used in that red oakis assigned a flame-spread ratingof 100 and reinforced inorganiccement board a flame-spread rating of 0, when both are testedon the floor of the tunnel.

Some materials, primarily foamedplastics, show anomalous behaviorin the tunnel. The flame frontinitially progresses rapidly, thenslows down or recedes, in mostcases not reaching the end of thetunnel.

A separate formula is used toassign a flame-spread rating forsuch materials. The formula isbased solely on the rate of flamepropagation along the surface ofthe material to the point wherethe flame front stops and beginsto recede.


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This formula was developedbecause the original formulaeyielded low flame-spread ratingsfor foamed plastics, when actualfire situations suggest much higher values.

In some tests conducted on eitherthe ceiling or the floor of the tunnel, certain materials exhibitrapid flaming across the surface.This makes it difficult to measurethe actual rate of flame propaga-tion. Another unusual case occurswhen a char layer forms, inhibit-ing burning along the surface of the material after an initialflash of flaming.

When either case occurs, the corner-wall test, ULC standardCAN/ULC-S127, must be used to assign a flame-spread ratinginstead of either of the ULC S102or S102.2 tunnel test methods mentioned earlier.

[2.5.3.1.] The NBCC allows theauthority having jurisdiction to accept the results of tests conducted in accordance withother standards provided they are considered equivalent. Itshould be noted, however, thattests performed under earlier editions of the CAN/ULC S102and S102.2 standards are not thesame as current editions becausethe calculation methods havechanged over the years to accountfor the properties of new materials.

This would also apply to the UStunnel standards, ASTM E84 andNFPA 255, which use similarapparatus but have minor operational differences.

In these two American standards,there are no provisions for testingproducts on the floor of the tun-nel. As a result, thermoplasticmaterials (including some foamedplastics), which melt or drip whenexposed to the fire obtain a lowerflame-spread rating in the USthan in Canada.

ALTERNATIVE DETERMINATION

[D-3.1.1.] The flame-spread rat-ing and smoke developed classifi-cation of a material may also bedetermined from the informationcontained in Appendix D of theNBCC.

Information is only provided for generic materials for whichextensive fire test data is avail-able (Table 6.1). For instance, lum-ber, regardless of species, andDouglas fir, poplar, and spruceplywood, of a thickness not lessthan those listed, are assigned aflame-spread rating of 150.

In general, for wood products up to 25mm thick, flame-spreadrating decreases with increasingthickness. Values given in theAppendix D of the NBCC are



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TABLE 6.1

Assigned flame-spread ratingsand smokedeveloped classifications

Paint or Varnish notMore than 1.3mm Thick,

Minimum Cellulosic Wallpaper Applicable Thickness Unfinished 3 not more than 1 Layer 5,6

Materials Standard mm FSR SDC FSR SDC

Hardwood or — — 300 300 softwood flooring 3

Gypsum wallboard CSAA82.27-M 4 9.5 25 50 25 50

Lumber None 16 150 300 150 300

Douglas Fir plywood 1 CSA O121 11 150 100 150 300

Poplar plywood 1 CSA O153 11 150 100 150 300

Plywood with CSA O151 11 150 100 150 300Spruce face veneer 1

Douglas Fir Plywood 1 CSA O121 6 150 100 150 100

Fiberboard low density CSA A247 11 > 150 100 150 100

Hardboard Type 1 CGSB-11.3 9 150 > 300 2 2

Standard 6 150 300 150 300

Particleboard CAN3-O188.1 12.7 150 300 2 2

Waferboard CAN3-O437 — 2 2 2 2

Notes:1. The flame-spread ratings and smoke developed classifications shown are for those plywoods

without a cellulose resin overlay.2. Insufficient test information available.3. Wood flooring unfinished or finished with a spar or urethane varnish coating.4. Gypsum Wallboard complying with the following ASTM standards is also acceptable - ASTM C36,

ASTM C442, ASTM C588, ASTM C630 & ASTM C931. 5. Flame-spread ratings and smoke developed classifications for paints and varnish are not

applicable to shellac and lacquer.6. Flame-spread ratings and smoke developed classifications for paints apply only to alkyd and

latex paints.

Source: Appendix D, Section D-3, 1995 NBCC


conservative because they areintended to cover a wide range of materials. Specific species and thicknesses may have valuesmuch lower than those listed in Appendix D.

Specific ratings by species aregiven in Table 6.2. Information

on proprietary and fire-retardantmaterials is available from ULClistings or from manufacturers.The values listed in Table 6.2 applyto finished lumber, however, therehas been no significant differencein flame-spread rating noted inrough sawn lumber.

TABLE 6.2

Typical flame-spread ratings and smokedeveloped classificationsof wood products

Product Flame-Spread Smoke DevelopedLumber, 19mm thickness Ratings Classification

Cedar Western Red 73 98

Pacific Coast Yellow 78 90

Fir Amabilis (Pacific Silver) 69 58

Hemlock Western 60-75

Maple (flooring) 104

Oak Red or White 100 100

Pine Eastern White 85 122

Lodgepole 93 210

Ponderosa 105-230

Red 142 229

Southern Yellow 130-195

Western White 75

Poplar 170-185

Spruce White 65

Sitka 74 74

Western 100

Shakes Western Red Cedar 69

Shingles Western Red Cedar 49

GENERAL

[3.1.13.1.(1)] Any material thatforms part of the building inte-rior and is directly exposed is considered to be an interior finish. This includes interiorcladdings, flooring, carpeting,doors, trim, windows, and light-ing elements.

If no cladding is installed on theinterior side of an exterior wall of a building, then the interiorsurfaces of the wall assembly areconsidered to be the interior finish,for example, unfinished post andbeam construction. Similarly, if noceiling is installed beneath a flooror roof assembly, the unfinishedexposed deck and structural mem-bers are considered to be the inte-rior ceiling finish.

PAINT AND WALL COVERINGS

When a surface finish such aspaint, wallpaper, wood veneer,fabric or plastic is applied to asubstrate such as plaster, gypsumwallboard or plywood, it is then considered as the interior finish.

Normally, the surface finish andthe material to which it is appliedboth contribute to the overallflame-spread performance. Mostsurface coatings such as paint and wallpaper are usually lessthan 1mm thick and will not contribute significantly to theoverall rating.

This is why the NBCC assigns the same flame-spread and smokedeveloped rating to common mate-rials such as plywood, lumber and

gypsum wallboard whether theyare unfinished or covered withpaint, varnish or cellulosic wall-paper (Table 6.1).

Paint and wallpaper of a conven-tional thickness usually provideadditional protection for theunderlying surface. Depending ontheir composition, they may evenslightly reduce the flame-spreadrating of the interior cladding.

There are also special fire-retardant paints and coatingsthat can substantially reduce the flame-spread rating of aninterior surface. These coatingsare particularly useful whenrehabilitating an older buildingto reduce the flame-spread ratingof finish materials to acceptablelevels, especially for those areasrequiring a flame-spread ratingno greater than 25.

Other coatings, such as fabricwall covering, which are usuallythicker than 1mm, can present afire hazard of their own and mustbe tested in accordance with thereference standard together withthe underlying material. This isbecause the substrate, includingany adhesives used, can signifi-cantly affect test results.

Veneers, such as corkboard andfibreboard, and other finishessuch as acoustic tiles or carpetingattached to interior wall cladding,are treated as surface coatingsrather than cladding.

Care must be exercised to specifyadhesives resistant to high temperatures so that finishes will not peel readily during a fire

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6.3 Interior Finishes

and expose the underlying surface.Phenol-resorcinol, melamine ormelamine-urea adhesives areoften used. These proprietarymaterials must, of course, be tested in accordance with ULCstandards.

[3.1.4.2.(1)] Foamed plastic materials are not permitted as an interior finish in occupied portions of a building. They mustbe protected by plywood, gypsumwallboard or other acceptablethermal barrier material evenwhen their flame-spread rating iswithin acceptable limits.

This requirement for a thermalbarrier is partly due to concernsfor smoke generation. It also takesaccount of the fact that, with nothermal barrier over the insula-tion product, there can be a fastertemperature build-up in a roomduring a fire. This can increasethe potential for flashover.

FLOORING

In a room fire, the flooring is usu-ally the last item to be ignited,since the coolest layer of air isnear the floor.

[3.1.13.7.(1)[&[(2)] For this reason,the NBCC, like most other codes,does not regulate the flame-spread rating of flooring, with the exception of certain essentialareas in high buildings:• exits• corridors not within suites• elevator cars• service spaces

However, with the new requirementsfor sprinklers in all high buildingsin the 1995 NBCC, the stricter limitsplaced on interior finishes, includ-ing floors, no longer apply except inGroup B major occupancies.

Traditional flooring materialssuch as hardwood flooring andcarpets can, therefore, be usedalmost everywhere in buildings of any type of construction.

It should be noted that carpetsglued or nailed to an unfinishedfloor are considered part of theinterior finish, while loose rugsare considered part of the build-ing contents. Similarly, woodbased panels used as a wearingfloor over a metal or concrete deckshould not be considered part ofthe structure or the interior floorfinish unless permanentlyattached to the deck.

[3.1.5.8.(4)] Where permanentlyattached, these wood panelswould be considered the finishedfloor, which is permitted to becombustible in noncombustiblebuildings in any case.

LIGHT DIFFUSERS AND LENSES

The NBCC also regulates lightdiffusers and lenses, which arethe panels that form the lightemitting portion of lighting fixtures. Modern fixtures are usually made from translucent ortransparent synthetic materials,many of which do not meet thebasic flame-spread requirementsfor interior ceiling finish.


[3.1.13.4.] Except for Group A,Division 1 occupancies, the NBCCallows the use of light diffusersand lenses that exceed the flame-spread rating limits required fora particular location providedthat, when tested in the tunnel inconformance with ULC StandardCAN/ULC-S102.3, StandardMethod of Fire Tests of LightDiffusers and Lenses, they fall tothe bottom of the test apparatusbefore being ignited.

This drop-down feature is requiredto avoid having a continuous surfacewhich could spread flames across aceiling in a real fire situation.

In addition, when these light diffusers and lenses are tested inaccordance with CAN/ULC-S102.2,they cannot have a flame-spreadrating exceeding 250 nor a smokedeveloped classification over 600.These lighting elements must beinstalled so that nothing belowwill prevent them from fallingout of the ceiling.

For increased fire safety, additionalrequirements apply to fire separatedcorridors and exits to ensure that thelighting elements are sufficientlyspaced from each other therebyreducing the flame-spread potential.

APPLICATION OF NBCC REQUIREMENTS

The level of NBCC requirementsfor flame-spread ratings is rela-tive to the importance of a spaceas a means of escape. The moreessential the space is as a link

to safety for a greater number ofoccupants in the building, themore restrictive the requirements.

From a room or suite, occupantswould normally escape to a spacecommon to many other rooms,such as a corridor, and proceed toa space, such as an exit stairway,toward which other floors wouldalso converge.

Obviously, maximum protectionwill be required in the exit stair-way, since a fire in the exit wouldjeopardize all occupants of thebuilding. A fire in a corridorwould hamper the evacuation of occupants on one floor alone.Even less stringent requirementswould apply in a room.

It should be noted that flame-spread requirements apply equally to combustible and noncombustible constructionbecause they concern the rate of fire spread along interior finishes, and not the structuralfire resistance of the structure.

[3.1.5.10.[&[3.1.13.8.] One peculiar-ity concerning noncombustibleconstruction should also be con-sidered: the flame-spread ratingof the material must apply notonly to the exposed surface butalso to any surface that would beexposed by cutting through thematerial in any direction.

Lumber and heavy timber meetthis requirement since they arehomogeneous; grain orientationdoes not affect flame spread.


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[3.1.5.10.(3)[&[3.1.13.8.(1)] Fire-retardant treated wood is exemptfrom the requirement, recognizingthat the fire-retardant chemicals,while reducing the surface flamespread rating, do not penetratethe entire wood member. Thisexception does not apply to fireretardant paints or coatingswhich are surface applied.

Composite wood products call forindividual consideration. Orientedstrandboard (OSB) and waferboardare relatively homogeneous.Products with definite glue planessuch as plywood and glue-laminatedtimber delaminate as they burn inthe tunnel test, so the effects of theglue are already reflected in theflame-spread rating. In practice, therule is meant to be applied to prod-ucts which may, realistically, beused with the surface laminationremoved.

[3.1.13.2.(1)] In general, theNBCC sets the maximum flame-spread rating for interior walland ceiling finishes at 150, whichcan be met by most wood products.

[D-3.1.1.] For example, 6mmDouglas Fir plywood may beunfinished, painted, varnished orcovered with conventional cellu-losic wallpaper. This has beenfound to be acceptable on thebasis of actual fire experience.

This means that in all areaswhere a flame-spread rating of 150 is permitted, the majorityof wood products may be used as

interior finishes without specialrequirements for fire-retardanttreatments or coatings.

[3.1.13.2.(2)] Doors are permittedto have a flame-spread rating of200 with exceptions commensurateto the occupancy hazard (morerestrictive for Group A, Division 1assembly occupancies, no restric-tions on doors within dwellingunits).

[3.1.13.6.(1)] In areas such as publiccorridors and corridors in care anddetention occupancies, the maximumflame-spread rating is set at 75, butthe NBCC will also allow the lowerhalf of walls in the corridor to have amaximum flame-spread rating of150 if the top half has a flame-spreadrating of not more than 25.

]3.1.13.2.(4)] Similarly, in allareas where a flame-spread ratingof less than 150 is required, up to10% of the wall and ceiling areacan have a rating of at most 150.This would apply to exits, where amaximum flame-spread rating of25 is required, and is generallypermitted to account for com-bustible trim, handrails andlighting fixtures.

The application of the require-ments for interior finishes in thoseareas where the NBCC imposesstricter limits is otherwise coveredin Tables 3.1.13.2. and 3.1.13.7.Tables 6.3 and 6.4 summarize theNBCC requirements by locationand element.


Description of NBCCRegulated Area Reference Interior Finish Requirements 2, 3

Buildings of noncombustible [3.1.5.4.] Walls: 150 FSRconstruction and • not more than 25mm in thickness

[3.1.5.10.] • FSR must be homogeneous throughout the material

Ceilings: 25 FSR• not more than 25mm in thickness except for

fire-retardant treated wood battens• FSR must be homogeneous throughout the material

except for fire-retardant treated wood• 10% of ceiling area within a fire compartment

may have up to 150 FSR

Combustible vertical glazing: • 75 FSR permitted up to the second storey• 150 FSR permitted on the first storey provided

glazing does not exceed 25 percent of the wall area 4

Group A, Division 1 [3.1.13.2.] 75 FSR 1, 6

occupancies including doors,skylights, glazing and lightdiffusers and lenses

Group B occupancies [3.1.13.2.] 75 FSR 1, 6

Public corridors, corridors [3.1.13.2.(4)] Walls: not more than 75 FSR 1 or upper half of used by the public in Group A and 25 FSR 1 and lower half of 150 FSR 6

and B occupancies and [3.1.13.6.]corridors serving classrooms

Ceiling: not more than 25 FSR 1, 6

and patients’ sleeping rooms

Other Occupancies [3.1.13.2.] 150 FSR

Doors in all occupancies [3.1.13.2.(2)] 200 FSRexcept Group A, Division 1

Doors within dwelling units [3.1.13.2.(3)] FSR not regulated

Bathrooms within suites of [3.1.13.3.] 200 FSRresidential occupancy

All buildings except Group A [3.1.13.4.(1)] Ceiling light diffusers and lenses not more than 250 FSR and 600 SDC with drop out requirement and size and separation restrictions

Exits including exterior exit [3.1.13.2.] 25 FSR 1. In noncombustible buildings the FSR mustpassageways described in and be homogeneous throughout the material except forArticle 3.1.13.10. providing [3.1.13.8.(1)] doors, fire-retardant treated wood and heavy timberthe only means of egress construction in sprinklered buildings.

Lobby used for exiting as [3.1.13.2.(1)] 25 FSR 1 except that up to 25% of the total wall area described in Sentence and not including combustible doors is permitted to have3.4.4.2.(2) [3.1.13.2.(4)] 150 FSR

Underground walkways [3.1.13.9.] Except for paint, only noncombustible materials permitted

Covered vehicular [3.1.13.2.(1)] 25 FSR 1

passageways except forheavy timber roof assemblies

Vertical service spaces [3.1.13.2.(1)] 25 FSR 1

Notes:1. Up to 10% of the total wall area and 10% of the total ceiling area is permitted to have a 150 FSR.

Except in Group A, Division 1 occupancies, doors, skylights, glazing and light diffusers and lensesneed not be considered in the calculation. [3.1.13.2.(4)]&[(5)]

2. FSR is the flame-spread rating and SDC is the smoke developed classification.3. Exposed foam plastics are not permitted on walls or ceilings. [3.1.4.2.]&[3.1.5.11.]4. In a sprinklered building, glazing is also permitted on second storey.5. Unless otherwise specified, FSR’s apply to both walls and ceilings.6. For sprinklered buildings, the FSR is permitted to be 150.

TABLE 6.3

NBCCrequirements for interiorfinish 5 and exterior glazing


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TABLE 6.4

Additional interior finishrequirementsfor high buildings regulated bySubsection 3.2.6.


Description of Interior Finish Requirements 2

Regulated Area Unsprinklered buildings Sprinklered buildings 1

Exit stairways, vestibules to Walls, ceilings and floors not see Table 6.3exit stairs, and exit lobbies more than 25 FSR and notdescribed in Sentence 3.4.4.2.(2) more than 50 SDC 3, 4

Corridors not within suites Walls not more than 100 SDC, see Table 6.3ceilings not more than 50 SDC.See Table 6.3 for FSR limits 3, 4

Floors not more than 300 FSRand not more than 500 SDC.

Elevator cars and vestibules Walls and ceilings not more than 25 FSR and not more than 100 SDC. Floors not more than 300 FSR and not more than 300 SDC.

Service spaces and Walls, ceilings and floors not see Table 6.3service rooms more than 25 FSR and not

more than 50 SDC

Lighting elements see Table 6.3 see Table 6.3

Other locations and elements Walls not more than 300 SDC, see Table 6.3ceilings not more than 50 SDC.See Table 6.3 for FSR limits.

Notes:1. Buildings of Group B major occupancy and elevator cars are not included.2. FSR is the flame-spread rating and SDC is the smoke developed classification.3. Does not apply to 10% of wall or ceiling finish including trim and millwork which

may have 150 FSR and 300 SDC.4. Does not apply to 10% of wall finish which may be doors which have 200 FSR

and 300 SDC.

GENERAL

Fire-Retardant Treated Wood(FRTW) is wood which has beenimpregnated with fire-retardantchemicals in solution under high pressure in accordance with CSAstandard O80, Wood Preservation(Figure 6.3).The treatment reducessurface burning characteristics,such as flame spread, rate of fuel contribution and smoke contribution.

To dispel any myths that may stillexist, the treatment does not makethe wood noncombustible. This ideastems from certain earlier codeswhich equated a 25 flame-spreadrating to noncombustibility.

FRTW contains different chemicalsthan products known as preserva-tive treated wood. However, thesame manufacturing process is used

to apply the chemicals. The prod-ucts are not interchangeable.FRTW products burn at a slowerrate than untreated wood products.

FLAME-SPREAD RATING

[3.1.4.4.] When FRTW is specifiedin the NBCC, it must have a flame-spread rating of not more than 25when tested in conformance withCAN/ULC-S102.

It therefore qualifies as an interiorfinish for any application since the most restrictive flame-spreadrating is 25.

FRTW must be identified by alabel from an independent testinglaboratory which indicates thatthe necessary tests were made andproduction controls maintained(Figure 6.2).

FIGURE 6.2

FRTW label

Fire-Retardant Treated Wood 213

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6.4 Fire-Retardant Treated Wood

Manufacturer’s name, address, and product name

-

For many wood species, and partic-ularly plywood and lumber in sizescommon to frame construction,treatment results in chemicalretentions high enough to obtain aflame-spread rating of 25 or less. Itshould be noted that the chemicalswill not usually penetrate theentire wood member; refusal willusually occur when the chemicalshave penetrated approximately13mm from the outer surface.

[3.1.13.8.] The NBCC recognizesthis special characteristic. FRTWis exempt from the requirementthat a material exhibit its assignedflame-spread rating, whatever itmay be, on any surface that wouldbe exposed by cutting through thematerial in any direction, if to beused for interior finish in noncom-bustible buildings.

The actual flame-spread rating of treated lumber or plywooddepends on the fire-retardantchemicals used and the amount ofchemicals retained in the wood.

Commonly used chemicals are proprietary mixtures which arefree of halogens, sulphates,ammonium phosphate andformaldehyde. These providesuperior performance characteris-tics over previous formulationsand lower corrosivity to metalfasteners. These water-solublechemicals are effective in reduc-ing flame spread, and throughcareful proportioning succeed inreducing smoke development andafterglow.

EXTERIOR USE

When FRTW products are used in areas where the material is

exposed to weather or highhumidity, it must be treated with special non-leaching chemicals similar to those used for fire-retardant treatedcedar shakes and shingles.

An accelerated weathering test(ASTM D2898) exposes FRTW toregular wetting and drying cyclesto represent actual long-term outdoor conditions. FRTW muststill achieve a flame-spread rating of 25 after undergoing this accelerated weathering inorder to qualify for exterior use.

]3.1.5.5.(4)]&[(5)] These require-ments apply to exterior gradefire-retardant treated plywoodsiding over wood studs in exteriorwalls of noncombustible build-ings and FRTW decorativecladding on exterior marquee fascias of noncombustible build-ings. (Chapters 2 and 4).

FIRE-RETARDANT COATINGS

Listed fire-retardant coatingsapplied to wood also reduce theflame-spread rating to less than75 or 25. These coated products canbe used for interior finish in non-combustible buildings exceptwhere the flame-spread ratinglimits apply not only to exposedsurfaces but also to surfaces thatmay be exposed by cutting throughthe product in any direction.

FRTW products are excludedfrom these requirements whileproducts protected by fire-retardant coatings are not. This recognizes the permanencyof the fire-retardant treatments.


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FIGURE 6.3

Loading wood into fire-retardant treatment pressure cylinder

GENERAL

All components of a roof assem-bly influence its performanceunder fire conditions.

In the past, roof assemblies wereassumed to be safe under fireexposure if the deck and its supports were constructed of noncombustible material eventhough the vapor barrier, adhesives and roof covering were combustible.

In 1953, one of the largest singlefire losses recorded ($45 000 000)proved the fallacy of thisassumption. At the GeneralMotors plant in Livonia,Michigan, highly combustiblevapors from asphalt roofingproducts leaked through the noncombustible deck, rapidlyspreading fire along the under-side of 14 hectares of roof. Thiscaused the collapse of the unpro-tected structural steel assembly

and rendered fire-fighting operations ineffective.

The Livonia loss prompted the development of improvedadhesives and vapor barriers to reduce the production ofvapors that could penetratemetallic roof decking and con-tribute to the spread of fire.

At the same time, an extensiveresearch and testing program was undertaken on large-scalespecimens (30.5m x 6m) to devel-op criteria for the performance ofroof assemblies. Large-scale testsare prohibitively expensive andfurther research was commis-sioned to devise a test using theSteiner flame-spread tunnel.

The result of this effort is incorporated in ULC standardCAN/ULC-S126, StandardMethod of Test for Fire Spreadunder Roof-Deck Assemblies. Itrequires the flame spread on the

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6.5 Roof Assemblies

FIGURE 6.4

FRTW roofassembly alternative

underside of the complete roofassembly not to exceed 3m in thefirst 10 minutes and not to exceed4.2m in the total 30-minute testperiod.

[3.1.14.2.] For metal roof deckassemblies, this requirement only applies in unsprinkleredbuildings permitted to be of combustible construction wherean unrated metal roof deck assembly is used in lieu of a rated combustible or FRTW roof assembly.

In such cases, any metal roof deckassembly, supporting combustiblematerial above the deck that couldpropagate a fire below the deck,must meet the standard unless:• the combustible material is

protected on the underside by a thermal barrier

• the building is sprinklered• the roof assembly has a

fire-resistance rating of at least 45 minutes

FIRE-RETARDANT TREATED WOOD ROOF SYSTEMS

In certain unsprinklered one-storeybuildings, the NBCC permits the useof a roof deck construction system,using FRTW, that meets the flame-spread performance standard origi-nally developed for noncombustibleroof assemblies.

[3.1.14.1.] The required fire-resistance rating of the roof assem-bly can be waived if the deck is con-structed of FRTW and the assem-bly passes the requirements ofCAN/ULC S126 (Figure 6.4).

For the fire-retardant treated roof system to meet the criteria ofCAN/ULC-S126, the treated woodmust have superior fire-retardantchemical retention so that it pass-es an extended flame-spread test.The flame-spread rating underthe standard 10-minute exposureof the CAN/ULC-S102 test must below enough (usually below 20),that the flame-spread rating will

FIGURE 6.5Fire-retardanttreated woodroof systems


Roof CoveringBuilt-up or prepared

Approved insulationor 25mm cane or wood-fibre board

Fastening Adhesive or mechanical(staples plus galvanized roofing nails)

SupportsFire-retardant treated lumber joists or trusses, untreated heavy timber, or noncombustible

Vapour BarrierAluminum sheeting or steel foil

DeckingFire-retardant treated plywood or lumber

not exceed 25 even with the testperiod extended to 30 minutes.

A roof deck system of FRTW maybe supported by:• metal and reinforced concrete

beams or joists• heavy timber supports• FRTW joists or trussesUnless wood members are heavytimber, which has an inherentcapacity to withstand fire exposure, they must be fire-retardant treated. Experienceshows that both lumber and plywood decking must have a minimum actual thickness of19mm and both should be tongueand groove. Plywood decking, ifnot tongue and groove, must alsohave unsupported joints solidlybacked with FRTW or plywood.

Figure 6.5 shows that the con-struction of roof assemblies usingFRTW is similar to that of othertypes of roof assemblies, using ametallic vapor barrier membranebetween the decking and the insulation. Usually 0.05mm alu-minum sheeting is attached withan approved adhesive, althoughsteel foil is also acceptable.Galvanized roof nails may be used to fasten the insulation tothe vapor barrier which is thenstapled to the deck.

FRTW or noncombustible ceilingsmay be attached to the undersideof the system, with the resultingconcealed spaces appropriatelyfire stopped.

FRTW roof assemblies are per-mitted as an alternative to roof

assemblies of noncombustible construction or ordinary wood-frame roof assemblies having a fire-resistance rating of 45 minutes. When used, however, the NBCC requires that, exceptfor Group E and Group F, Div. 3occupancies, the area of thebuilding be half that whichwould be permitted if either of the other two types of roofassembly were used.

These building area limits areimposed where FRTW roofs areused because FRTW roof systemsare generally open, subject todirect exposure from a fire belowand consequently are less struc-turally stable during a fire.

As noted earlier, fire-retardantcoated wood is not the same asFRTW and therefore is not permitted to be used under thisrequirement unless the systempasses the extended 30-minutetunnel test (CAN/ULC-S126).

ROOF COVERINGS

Roof coverings have often beencontributing factors in conflagra-tions. Most roof coverings, eventoday, are combustible by the verynature of the materials used formaking them waterproof.

The objective of the NBCC istherefore to require that the risks associated with a roof cover-ing be minimized for the type ofbuilding, its location and use.

There are two main types of product used for roof covering.First, there are the built-up roofmembranes such as tar and gravel

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that are laid in several operationsand the more recent single-ply synthetic roofing materials.Second, there are the preparedcoverings which include shingles,shakes, tiles and roll roofing thatcome from the manufacturerready to install over the underlayand roof deck in one operation.

TESTING

[3.1.15.1.] The NBCC requires that roof coverings be tested inaccordance with ULC standard

CAN/ULC-S107, StandardMethods of Fire Tests of RoofCoverings. These independent lab-oratory tests are for performanceunder external fire exposure.

The test illustrated in Figure 6.6concentrates on three features:• the ease with which the surface

of the roof covering can beignited by direct flame or byburning brands landing on the roof

• the extent of flame spread overthe roof surface when a flame


Air introduced from outside the test roomby blower controlled by rheostat

Air duct

Inorganic reinforced cement board sides

Floor level

Construction ofinorganic reinforced

cement board tosimulate eaves

and cornice

94mm height of velometer nozzle

Test specimen mountedon framework, pitch can

be adjusted

location of thermocouple

Baffle to prevent backfiring under test deck 762mm

1520mm spacing of framework when making

burning brand test

343mm

92mm

152 178 235 273

114mm127mm

343mm

889mm

1320 mm

1110mm

25mm gas supply line

Gas Burner of 51mm diameter pipe, 1118mm long, with 914mm long slot in sidetoward specimen, 12.7mm wide

To get uniform gas pressure at the burner,gas is piped to both ends

Fins to reduce turbulance and straighten air stream

Test Specimen

Location ofvelometer reading

Thermocouple

To gas supply

2135mm

Section

Plan

Source: ULC-S-107

Inorganic reinforcedcement board sides

1020mm

FIGURE 6.6

Test apparatusfor roof covering materials

is directed onto the lower edgeof the roof deck

• the tendency for flaming orglowing pieces of the roof covering to break loose in flying brands that can be carried away from the roof onto other portions of the roof or onto other structures

The same test is applied to built-up and prepared types ofroof coverings, conducted with theproduct installed on a metal roofdeck. This determines, as nearlyas possible, how it will performwhen in place on a building andexposed to various degrees of fireseverity.

After the product has been classi-fied through initial testing, thetesting laboratory continues to

monitor production, and makesperiodic tests to ensure that original qualities and propertiesare maintained. A roof coveringproduct that meets and maintainsstandards is qualified to carry alabel issued by the testing labora-tory designating its classification.

The standard classifies roof coverings in accordance with their performance:• Class A perform well under

severe fire test exposures• Class B under moderately

severe exposures• Class C under less severe

exposure

[3.1.15.2.]&]3.1.5.3.(1)] The NBCCpermits roof coverings that meetthe Class C rating to be used

Roof Assemblies 221

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FIGURE 6.7

Wood shingleroof

for any building regulated byPart 3 of the Code, including any noncombustible building,regardless of height or area.

This C rating can be met easilyusing FRTW shakes or shingles,asphalt shingles, or roll roofing.

[3.1.15.2.(2)] Small assembly occu-pancy buildings not more than twostoreys in building height and lessthan 1000 m2 in building area do notrequire a classification for the roofcovering. In these traditional cases,untreated wood shingles are accept-able if they are underlaid with anoncombustible material to reducethe potential for burn through witha burning brand (Figure 6.7).

[2.5.3.1.] As with other test methods, the authority havingjurisdiction may accept theresults of other fire test standardsor of earlier versions of the referenced standards, provided it is satisfied that the results are equivalent to those obtainedusing CAN/ULC-S107.

The equivalent U.S. standardspublished for this applicationinclude:• UL 790 Tests for Fire Resistance

of Roof Covering Materials• ASTM E-108 Standard Test

Methods for Fire Tests of RoofCoverings

• NFPA 257 Standard Methods of Fire Tests of Roof Coverings

All of these test methods are very similar to the Canadiancounterpart. The results of testsconducted in accordance withthese other test standards should,therefore, be acceptable.

When approving a roof coveringtested under an equivalentmethod, it is important thatresults of all individual types of fire tests required by the standard are provided.

These individual tests includeassessment for:• spread of flame• burning brands• intermittent flame exposure• flying brand production

Very few changes have been madeto these standards over the yearsand tests performed under earliereditions are still valid today.

It should be noted that in the case of FRTW shakes and shingles, accelerated weatheringand actual long-term weatheringtests are carried out to ensurethat the effects of fire-retardanttreatment will not be reduced bycontinuous exposure to weather.

Six decks are submitted to a standard rain test (ASTM D2898)and subsequently submitted to the various fire tests called for by the ULC standard. In addition,15 test decks are weathered outside for periods of exposure of one, two, three, five and 10 years.

At the end of each time period,three of the decks are removedfrom the exposure site, condi-tioned as specified in the standardand submitted to the same firetests. Fire retardant coatings typically cannot meet all the requirements of a Class C rating because of these extreme weathering tests.


Roof Assemblies 223

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Chapter SummaryThe NBCC strictly regulates the flame-spread potential ofinterior finishes because their contribution to fire growthcan significantly affect the ability of occupants to safelyevacuate the building.

The flame-spread limits are essentially dependent on theimportance of the area under consideration with regard to evacuation.

The limits contained in the NBCC permit extensive use ofuntreated wood finishes. Fire-retardant treated wood canoffer attractive and economical solutions in areas whereflame-spread limits do not permit the use of untreated wood products.

The use of FRTW can also waive fire-resistance requirements for roof assemblies in some cases.

The NBCC also regulates the flame-spread potential ofroofing materials, as well as other properties includingtheir propensity to be ignited by burning brands, to reducethe hazard of fire spreading from roof to roof.

7Fire SpreadBetweenBuildings7.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

The St. Lawrence Burns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

7.2 Objectives and Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 229

7.3 Limiting Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

Area of Exposing Building Face . . . . . . . . . . . . . . . . . . . . . . . . 237

Construction of Exposing Building Faces . . . . . . . . . . . . . . . . . . 238

7.4 Exceptions to Spatial Requirements . . . . . . . . . . . . . . . . . . . 243

Unlimited Unprotected Openings in Building Faces . . . . . . . . . . 243

Reduced Fire Resistance in Low Fire Load Buildings . . . . . . . . 243

Increased Area of Openings for Wired Glass . . . . . . . . . . . . . . . 244

Equivalent Opening Factor for Exterior Walls . . . . . . . . . . . . . . . 244

7.5 Exposure Protection Within a Building . . . . . . . . . . . . . . . . . 245

Horizontal Fire Spread Between Compartments . . . . . . . . . . . . 245

Vertical Fire Spread Between Floors . . . . . . . . . . . . . . . . . . . . . 247

Fire Exposure of Exit Facilities . . . . . . . . . . . . . . . . . . . . . . . . . 249

7.6 Examples of Spatial Separation Calculations . . . . . . . . . . . . 251

Example 7.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251

Example 7.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254

Example 7.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256

Example 7.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264

A fire in one building is always athreat to neighboring buildings.Thermal radiation or convectionthrough windows or other unprotected openings could ignite combustible materials in or on a nearby building.

To reduce this risk, a number of measures are used. Theseinclude:• limiting the number and size

of openings in the building face

• requiring buildings to be noncombustible

• requiring buildings to be cladwith noncombustible siding

• separating the buildings by aclear space

The measures chosen depend on the likely severity of the fireand radiation from the face of the building where the fire originates.

This chapter explains the objec-tive and rationale behind NBCCrequirements for preventing firespread between buildings. As well,examples of calculations for spatial separations are provided.

THE ST. LAWRENCE BURNS

Early NBCC requirements for spatial separation of buildingswere based on British andJapanese studies performed dur-ing post-war years. Most of thedata on the relationship betweenspatial separation and tolerableradiation levels evolved fromCanadian experiments referred toas the St. Lawrence Burns.

When the St. Lawrence Seawaywas under development in the1950s, a number of small townsnear the existing shoreline had tobe expropriated and demolished.The National Research Council'sDivision of Building Research(now the Institute for Research inConstruction) saw the abandonedbuildings as ideal for fireresearch experiments.

The burns, conducted in the winter of 1958, were designed to observe critical fire develop-ment factors such as:• its effect on the survival of

occupants• its effect on the spread of fire

by radiation• the effect of ventilation rates

in the room of fire origin

The proximityof buildings is controlled to reducepotential forconflagrations


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The objectives of the study were to determine at what distancesintensities of radiation would besufficient to ignite combustiblematerials in adjacent structures,and the intensity of thermal radiation at window openings.

The study concluded that:• the radiation levels from build-

ings with combustible interiorfinishes were double thosewhere noncombustible interiorfinishes were used

• peak radiation levels at somedistance from the buildingwere found to be directly related to the percentage ofopenings in the exterior wall

• radiation levels during the first 16 minutes rarelyexceeded 25% of maximumradiation levels. In most cases,radiation levels were onlyabout 20% of maximum after20 minutes

• maximum radiation levels were not greatly affected by the type of exterior cladding.

These findings are the basis ofNBCC requirements that applytoday.


The objective of the NBCC require-ments for spatial separation andexposure protection of buildings is to prevent fire spread betweenbuildings.

Spatial separation, though a primary means of attaining thisobjective, is not always the bestmethod. In major urban areas,where land is expensive, large set-backs from property lines willhave a serious economic impact ona project.

The level of thermal radiationemitted from the face of a burningbuilding is directly related to thenumber and size of the openings inthe building face. Therefore, alimit on such openings will reduceradiation and allow buildings tobe closer together.

Buildings could be situated veryclose together if exterior walls facing neighboring properties wereconstructed as firewalls, and hadno openings which could emit radi-ation. It is more common, however,to combine spatial separation withcontrol on the amount and size ofopenings in the exterior wall inorder to prevent fire spreadbetween buildings (Figure 7.1).

The NBCC generally uses theterm unprotected opening to refer to doors, windows or otheropenings in a building face thatare not protected with a closure(see Chapter 5 for an explanationof closure).

Normally, openings through theexterior wall of a building (such as windows) are not protected by

FIGURE 7.1

Spatial separationdeterminesboth wall constructionand amount of openingspermitted

Objectives and Assumptions 229

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7.2 Objectives and Assumptions

closures because they are neitherpractical nor economical.

By definition, however, an unpro-tected opening is also any part ofthe building face that has a lesserfire-resistance rating than thatrequired for the exposing buildingface. The exposing building face isan exterior wall of a building thatcould expose another building to thermal radiation and therebycause fire to spread from onebuilding to another.

[3.2.3.] The NBCC limits the maximum area of unprotectedopenings permitted in an exposingbuilding face, expressed as a percentage of the area of theexposing building face.

The spatial separation values are based on the followingassumptions:

• The exposing building face is arectangle in a vertical plane.

• The exposing building face isparallel to the exposed surface.

• The fire department should be able to respond and set upoperations within 15 to 20 minutes of the outbreak of fire.

• The exposing building face is agrey radiator.

Grey radiator means that theunprotected openings are assumedto be uniformly distributed acrossthe building face and that, during afire, heat will be uniformly emittedfrom the entire surface at a rateproportional to the ratio of the totalarea of unprotected openings to thearea of the exposing building face.

As mentioned in Section 7.1, radiation levels within the first20 minutes are only about 20% ofthe maximum radiation levels.Spatial separations are based on the assumption that the firedepartment will be at the scene to control exposure after the first20 minutes of the fire.

]3.2.3.1.(5)] If firefighting ser-vices cannot reach a fire scenewithin 10 minutes of an alarmbeing received (which could be the case in isolated rural areas) theNBCC requires that the limitingdistance be doubled for buildingsthat are not sprinklered through-out. Because radiant energy isinversely proportional to distancesquared, the increased separationdistance reduces the exposure toacceptable levels.

For a given limiting distanceand total area of exposing build-ing face, the percentage of per-mitted unprotected openings isdetermined by the geometry ofthe building face. This affectsthe total amount of heat that will be radiated.

The NBCC bases the maximumpermitted area of unprotectedopenings for unsprinklered buildings on the aspect ratio of the exposing building face. This ratio is expressed as eitherlength/height or height/length.

[3.2.3.1.] In the 1995 NBCC, different sets of spatial separationtables apply for sprinklered andunsprinklered buildings. It isassumed that the entire exteriorwall face of a sprinklered build-


ing will not become involved in afire. This is because the sprinklersystem limits the maximum sizeof a fire.

Consequently, the need to considerthe effect of the aspect ratio of the height and length of thebuilding is removed. Also, it isexpected that fires in sprinkleredbuildings will not involve theentire exterior wall.

The maximum area of the exterior wall face that need beconsidered in determining spatialseparations for any sprinkleredbuilding is:• 200m2 for Group E and Group F,

Division 1 and 2 occupancies• 150m2 for all other occupancies

The maximum area of exposingbuilding face used for unsprin-klered buildings is 2000m2.

These maximum areas were determined on the basis of theapplicable engineering designsallowed by the NFPA sprinklerstandards. In the design stan-dards, the expected size of the fire in a sprinklered building isassumed for each occupancy. It isassumed that the maximum floorarea that will be involved in afire in a sprinklered building is465m2 and the maximum lineardimension is 26m.

The maximum exposing buildingface areas for sprinklered build-ings were determined using thesesmaller base floor areas andassuming that the sprinklerslimit fire to a single storey.

[3.2.3.1.] As a result, the 1995NBCC, significantly reduces theminimum spatial separationrequirements for sprinkleredbuildings and allows for greateramounts of unprotected openingsto be present. The doubling of thelimiting distance for delayed firedepartment response no longerapplies to buildings that aresprinklered throughout.

[3.2.3.7] As well, the constructionand cladding requirements for theexterior walls are now appliedafter the effect of sprinklers areconsidered by using the spatialseparation tables specificallyapplicable to sprinklered buildings.

[3.2.3.11] The credit normallyapplied for the use of wired glassor glass block in exterior wallopenings is not applied in sprinklered buildings. This isbecause the impact of their usewould not be significant since thefire in the building is controlledor suppressed by the sprinklers.

Objectives and Assumptions 231

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Consider two unsprinklered build-ings on lots A and B (Figure 7.2.)

The owner of Building A,Situation A, constructs the firstbuilding and locates it next to the property line with windowscovering 80% of the wall adjacentthe property line. This is not inaccordance with spatial separa-tion rules.

When owner B comes to constructa building, the authority having

jurisdiction would impose alengthy set-back or restrictions onopenings and wall constructionmaterials to offset the proximityof Building A to the property line.Obviously, this unfairly penalizesthe owner of the building on lot B.

On the other hand, if the con-struction and number of openingsfor both buildings had been estab-lished on the basis of the lot line(Situation B), both buildings

FIGURE 7.2

LimitingDistance

Limiting Distance 233

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7.3 Limiting Distance

Lot A Lot B

Building A

Pro

pert

y Li

neP

rope

rty

Line

Building face with 80%unprotected openings

within 1m of property line.

Lot A Lot B

Building A

Pro

pert

y Li

neP

rope

rty

Line

Equal amounts ofunprotected openings for equivalent distance

from property line.

Building B

Equal amounts ofunprotected openings for equivalent distance

from property line.

Situation A

Situation B

could have the same amount of openings for an equivalent distance from the property line.

The NBCC only regulates a building under construction, independently of buildings onadjacent sites. Therefore, theremust be a reference line for calculating spatial separationand the area of unprotected open-ings permitted for each building.

The distance which must be maintained from the referenceline is referred to as the limitingdistance.

This limiting distance is calculated from the exposingbuilding face to one of:• the property line• the centre line of a street or

public thoroughfare• an assumed line between two

buildings or fire compartmentson the same property

Note that the assumed line does nothave to be equidistant from the twobuildings or fire compartments.

The distance required between abuilding and the reference line isproportional to the amount ofunprotected openings in its expos-ing building face. Inversely, thearea of unprotected openings per-mitted in an exposing buildingface is reduced as the distance tothe reference line decreases.

[TABLES][3.2.3.1.A.]&[3.2.3.1.B.]The application of the NBCCrequirements for spatial separation is simplified by Tables 3.2.3.1.A. and 3.2.3.1.B. for unsprinklered buildings.

[TABLES][3.2.3.1.C.]&[3.2.3.1.D.] As mentioned, the spatial separationrequirements are easier to applyand are significantly less restric-tive for sprinklered buildingsthan for unsprinklered buildings.Tables 3.2.3.1.C and 3.2.3.1.D. contain the values for permittedunprotected openings based onlimiting distance and the size ofthe exposing building face.

Separate tables are used for mercantile and high-hazardindustrial occupancies. Theseoccupancies are assumed to have alarger combustible content whichwould result in higher thermalradiation levels.

In buildings where these higherhazard occupancies are found, the percentage of unprotectedopenings permitted for a givenlimiting distance is approximatelyhalf of that permitted for otheroccupancies.

In sprinklered buildings, themaximum limiting distance need-ed to permit 100% unprotectedopenings is:• 15m for any Group E or Group

F, Div. 1 or 2 occupancies• 9m for the other occupancies

In unsprinklered buildings, these distances can reach as highas 70m and 50m respectively forbuildings having large exposingbuilding faces.

The tabulated values for limitingdistance are based on the assump-tion that the exposing buildingface is a rectangle in a verticalplane, and the exposed surface lies


in a parallel plane. This assump-tion simplifies the application ofspatial separation requirementswith little loss in accuracy.

[3.2.3.1.(3)] Irregularly shapedbuilding faces must be projectedonto a vertical plane. This verti-cal plane must be positioned sothat no portion of the buildingextends horizontally beyond it.The limiting distance is thenmeasured from this vertical planeto the real or reference line.

The actual area of unprotectedopenings is taken as the area ofunprotected openings in the exte-rior wall projected onto the plane.

]3.2.3.1.(4)] If a building has allthe unprotected openings locatedin wall sections which are setback from the front face, then atwo-stage calculation can be made(Figure 7.3).

The first stage determines the construction requirements for the exterior wall of the building(see Construction of ExposingBuilding Faces). First, the permis-sible area of unprotected openingsat the plane of the external face of the building closest to the property line is determined. Thepermitted area of unprotectedopenings is expressed as a percent-age of the area of the projection ofthe building face. This percentageis then used to determine the typeof construction and FRR.

The second stage determines thepercentage of unprotected open-ings permitted. The permissablearea of unprotected openings iscalculated using the distance tothe plane of the recessed openings.

The percentage of unprotectedopenings actually permitted willbe greater because of the increasedlimiting distance. The Appendixto the NBCC 1995 further illus-trates how this calculation is made.

With this NBCC calculationmethod, a small blank wall projection close to the propertyline may govern the type of construction permitted for anentire building face.

The NBCC permits other methodsof evaluating spatial separationrequirements to be used. Informa-tion on these methods is containedin the Bibliography References 37, 38, 55, 85, 86 and 87 in theAppendix of this book.

Interpolation of the NBCC tablesis permitted when the limitingdistance or the percentage ofopenings falls between the values in the tables.

Interpolation is not permitted inunsprinklered buildings, however,for a limiting distance between 0 and 1.2m because flames can projecthorizontally 1 to 1.2m beyond anopening.

[3.2.3.5.] The NBCC requires thatopenings in an exposing buildingface that has a limiting distance of less than 1.2m be protected by closures. Wired glass and glassblocks are not permitted as closuresfor this application because it isassumed that they only reduce radiation by one half. This reductionis insufficient to control the spreadof fire to neighboring buildingswhere the limiting distance is less than 1.2m.


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FIGURE 7.3

Limiting distance andrecessed opening


Reference Line

Limiting Distancefor determining type of construction and FRR.

Reference Line

Limiting Distancefor determining percent ofunprotected openings permitted

Stage 1

Stage 2

AREA OF EXPOSING BUILDING FACE

[3.2.3.2.(1)] The area of an expos-ing building face is typically measured vertically from groundlevel to the ceiling of the top storey,and horizontally from the interiorsurfaces of the exterior walls.

[3.2.3.2.(2)] Other measures areused for buildings which are divid-ed into fire compartments designedto control the movement of firewithin the building. The NBCCpermits the exposing building faceto be calculated on the basis ofindividual fire compartments.

Measurements are made verti-cally between interior surfaces ofhorizontal fire separations andhorizontally between interiorsurfaces of walls constructed asfire separations.

Creating fire compartments in a floor area by the use of interiorfire separations will reduce thearea of the exposing building faceradiating heat in a fire situation.

This reduction in the area of theexposing building face can permita greater area of unprotectedopenings. This in turn reduces the requirements for exterior wall construction.

FIGURE 7.4

Compart-mentation and exposingbuilding face


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FRR greater of:Floor Ratingor45 minutes

Mercantile, High and Medium Hazard Industries

Notes:1. With vertical fire separation continuous from front to back of the building, the two sections of

exterior wall can be considered separate exposing building faces.2. If floor assemblies are continuous fire separations with openings protected, the area of the

exposing building faces can be reduced further.

The fire separations boundingeach compartment must be continuous both vertically andhorizontally (Figure 7.4).

[3.2.3.2.] For these provisions toapply, each fire compartmentmust be completely separatedfrom other parts of the buildingby fire separations that meet the following conditions:• For Group A, B, C, D, or Group

F, Division 3 occupancies, thefire-resistance rating must beat least one hour, unless thefloor assembly is permitted tobe less than one hour by 3.2.2,in which case the minimumFRR is 45 minutes.

• For Group E or Group F,Division 1 and 2 occupancies,the fire separations around afire compartment must be atleast 45 minutes and must notbe less than the FRR requiredfor the floors above and belowthe compartment.

Where combustible construction is permitted, parts of buildings(such as rooms or suites) can beconsidered as fire compartmentswhen surrounded by 45-minuterated wood-frame walls and floors. Wood assemblies can be designedto provide up to a two-hour fire-resistance rating.

[3.2.3.2.(6)] In sprinklered build-ings containing interconnectedfloor spaces, each storey is permit-ted to be considered as a separatefire compartment. The presence ofthe large openings through the

floor assemblies can be ignored inthis case as it is assumed that thesprinkler protection in the build-ing will control fire spread fromfloor to floor.

CONSTRUCTION OF EXPOSING BUILDING FACES

Where the percentage of permitted unprotected openings is restricted, the balance of the wall must have some fireendurance to ensure that the radiating area does not increaseduring a fire.

Should an exterior wall fail in the early stages of a fire, the areaof unprotected openings couldsuddenly become 100% of theexposing building face. If the limiting distance were based on a permitted area of unprotectedopenings of 10%, this distancewould obviously now be of marginal value in preventing the spread of fire.

Note that the permissible area of unprotected openings may consist of unrated, unrestrictedwall construction, doors and windows (Figure 7.5).

[3.2.3.7.] Table 7.1 summarizes theNBCC requirements for the con-struction type and fire-resistancerating for the exposing buildingface. The need for noncombustibleconstruction and cladding and therequirements for fire resistancerelax as the permitted area ofunprotected openings increases.


TABLE 7.1

Construction ofexterior walls


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FIGURE 7.5

Walls as unprotectedopenings

Unprotected Opening10% of building face

If 60% of Exposed Building Face is permitted to be unprotected openings,and in this situation 10% is an unprotected opening, 50% (lighter shaded area) may be unrestricted wall construction.

MinimumFire-Resistance

Unprotected Rating forOpenings Exposing

Occupancy Permitted, Building Face, Wall ExteriorClassification percent hours Construction Cladding

A, B, C, D 0 to 10 1 Noncombustible Noncombustible

and F-3 > 10 to 25 1 Combustible 1 or Noncombustible 2

Noncombustible 3

> 25 to < 100 3/4 Combustible 1 or Combustible 1 or Noncombustible 3 Noncombustible 2

100 None Required Combustible 1 or Combustible 1 or Noncombustible 3 Noncombustible 2

E, F-1 0 to 10 2 Noncombustible Noncombustible

and F-2 > 10 to 25 2 Combustible 1 or Noncombustible 2

Noncombustible 3

> 25 to < 100 1 Combustible 1 or Combustible 1 or Noncombustible 3 Noncombustible 2

100 None Required Combustible 1 or Combustible 1 or Noncombustible 3 Noncombustible 2

Notes:1. If building is permitted to be of combustible construction by Subsection 3.2.2.2. Combustible cladding assembly can be used on noncombustible buildings if cladding meets the

vertical flame spread limits of Article 3.1.5.5.3. Wood stud framing can be used in non-loadbearing portions of exterior walls of noncombustible

buildings when permitted area of openings exceeds 10% (see Chapter 2).

There is little point in requiringnoncombustible construction and cladding for a building facethat is permitted to have 100%openings. In such cases, spatialseparation rather than structuralconfinement becomes the control-ling factor.

[3.1.7.3.(3)] As noted in Chapter 5,the fire-resistance rating for anexterior wall assembly is requiredfrom the inside only. A fire-resis-tance rating from the outside isnot required, regardless of the limiting distance specified or thepercent of unprotected openingspermitted.

[3.2.3.3.] To simplify the calcula-tion of the area of the exposingbuilding face, the area of a gableend in an attic does not have to beincluded. However, the gable mustbe constructed to the same require-ments as the exposing building facebelow. This is intended to inhibitfire from reaching the concealedattic space, igniting the gable endwall, and increasing the radiation.

Structural members, such asbeams, columns or arches, that areentirely outside the exterior build-ing face or that are cantileveredfrom the building interior to theexterior, are not considered part ofthe exposing building face. Thelimiting distance is measured from the wall rather than from the furthest horizontal projectionof such structural members.

[3.2.3.8.(1)] No protection fromexterior fires is needed for anexterior structural member thatis at least 3m from a property line or from the centre line of a public thoroughfare. At this distance, it is unlikely that themember will be exposed to a firein a neighboring building of sufficient intensity to cause structural collapse.

Structural members of heavy tim-ber have inherent fire resistanceand need not be covered to protectthem from exterior or interiorfires.

[3.2.3.8.(2)] When structural members are less than 3m from aproperty line, they must have afire-resistance rating of not lessthan that required for interiorloadbearing members, but notless than one hour (Figure 7.6).

[3.2.3.6.] NBCC requires thatcombustible projections such asbalconies and eaves on the exteri-or of buildings be 1.2m from theproperty line or 2.4m from a combustible projection on anotherbuilding on the same property.

This ensures that the addition of combustible balconies on abuilding face does not negate theprotection offered by this spatialseparation.



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If > 3m, then heavy timber member need not be covered with noncombustible cladding.

Property LineLimiting Distance

Heavy Timber Structure

FIGURE 7.6

Limiting distance for exteriorstructuralmembers

The NBCC allows several excep-tions to the requirements for spatialseparation and exposure protection.

UNLIMITED UNPROTECTEDOPENINGS IN BUILDING FACES

[3.2.3.9.(2)] If the limiting distance is at least 9m, a firecompartment at street level may have unlimited unprotectedopenings in the building facefacing the street, regardless ofthe area of unprotected openingsotherwise permitted.

This exception was granted toallow traditional store fronts inmercantile occupancies but todayapplies to any occupancy at street

level. Exposure hazard to buildingson the other side an 18m widestreet is considered minimalbecause of easy firefighting access(Figure 7.7).

[3.2.3.9.(1)] An open-air parkinggarage is permitted to have un-limited openings on every storey provided a limiting distance of 3m is maintained. Tests haveshown that fire exposure fromopen-air garages is minimal.

REDUCED FIRE RESISTANCE IN LOW FIRE LOAD BUILDINGS

[3.2.3.10.] One-storey, low-hazardindustrial buildings with a lowfire load, such as power generating

Exceptions to Spatial Separation Requirements 243

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7.4 Exceptions to Spatial Separation Requirements

First StoreyUnlimited Unprotected Openings

Second StoreyUnlimited Unprotected Openings

Street access for firefighting

Unlimited unprotected openings are permitted in both portions of building faces located at a street level.

Street access for firefighting

FIGURE 7.7

Unlimitedunprotectedopenings atstreet level

plants and plants that manufacturemasonry products, are also exemptfrom most spatial separationrequirements because they are considered very low fire hazards.

The construction of such buildings and their contents arepredominantly noncombustible. If the limiting distance is at least3m, no fire-resistance rating isrequired for nonloadbearing wallsof noncombustible construction.

INCREASED AREA OF OPENINGS FOR WIRED GLASS

[3.2.3.11.] In unsprinkleredbuildings, the area of unprotectedopenings in an exposing buildingface is permitted to be doubled ifthey are fitted with wired glassor glass blocks. These windowsreduce radiation levels by approximately 50%.

[3.2.3.7.] The construction require-ments for exposing building facesshown in Table 7.1 must be metbefore the area of unprotectedopenings is doubled.

TABLES][3.2.3.1.C.]&[3.2.3.1.D.]The 1995 NBCC does not permit the doubling of permitted unpro-tected openings for sprinkleredbuildings (as was the case in previ-ous editions). The specific spatialseparation Tables for sprinkleredbuildings include the sprinklerreduction factor.

The reduction for wired glass orglass block does not apply forsprinklered buildings because the maximum reduction in radiantheat expected from the window has already been accounted for in recognition of the effect of thesprinklers.

EQUIVALENT OPENING FACTORFOR EXTERIOR WALLS

[3.2.3.1.(6)] The NBCC require-ment for an equivalent openingfactor often leads to confusion. Itwas introduced specifically formanufactured steel buildings withuninsulated metal sides; primarilystorage buildings.

Even though manufactured steelbuildings are noncombustible, thesides can become red-hot whenexposed to a fire. In these cases, theassembly fails the fire test and theentire wall surface would be con-sidered as an unprotected opening.

However, these walls are normallybuilt with few openings, so thatwhen the building collapses thefire tends to be smothered. Totreat these buildings in the sameway as those with 100% unprotect-ed openings, simply because ofheat transmission through thewalls, would be an unnecessaryrestriction.The correction forincreased radiation increases thearea of unprotected openingsabove actual values.

[3.1.7.2] The NBCC thereforewaives the temperature transmis-sion criteria for exterior walls,with a limiting distance of atleast 1.2m providing a correctionis made for increased radiation.

Data from fire-resistance tests onsample assemblies are required for the calculation. The tempera-ture of the unexposed wall surfaceat the time the required FRR isreached is required. This must beobtained from the testing agency.


Most spatial separation require-ments are intended to prevent thespread of fire from one building toanother.

The NBCC also contains require-ments addressing the potentialfor fire spread from one fire compartment to another, withinthe same building. Fire mayspread through openings in theexterior or interior walls or floorsor ceilings.

Fire exposure of exit facilitiesfrom the exterior of the buildingis also a potential hazard whichmust be avoided.

Within a building, floors andwalls are constructed as fire separations to impede the spreadof fire from one part of the build-ing to another. Fire separationsare also constructed to protectbuilding exits. The function of thefire separation can be defeated bythe presence of openings in theexterior envelope of the building.

Fire can bypass fire separations asfollows:• compartment to compartment

horizontal spread via unpro-tected openings

• floor to floor vertical spreadvia skylights and windows

• floor to floor vertical spreadvia window openings

• compartment to compartmenthorizontal spread via soffits

Exit facilities can be exposed tofire by the following:• exterior openings in exit

enclosures• exterior exit doors• unenclosed exterior exit stairs

The NBCC specifies additionalrequirements for each case toreduce the possibility of firespread or fire exposure from exterior openings in the building.

HORIZONTAL FIRE SPREADBETWEEN COMPARTMENTS

Unprotected Openings

The potential for horizontal firespread between fire compartmentsexists where exterior walls meetat an angle. Flames and radiationprojecting from an unprotectedopening in one fire compartmentcan impinge on an unprotectedopening in another fire compart-ment.

[3.2.3.13.] The NBCC considersthat there is a potential for firespread between separate fire compartments when the anglebetween the exterior walls of a building is 135° or less and the walls contain unprotectedopenings in close proximity to one another.

The NBCC sets a minimum dis-tance, D0 , which must separateopenings in these cases. Also, the construction of the portion of the wall between the openingsis required to have a fire-resis-tance rating at least equal to

Exposure Protection Within a Building 245

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7.5 Exposure Protection Within a Building

that required for the internal fire separation between the twofire compartments. (Figure 7.8)

This requirement does not applyto exterior exit doors or openingsin the exterior wall of an exitenclosure exposed to openings in adjacent exterior walls. (SeeFire Exposure of Exit Facilitiespage 249)

Where the openings are in sepa-rate fire compartments in thesame building, the requirementsdo not apply if the building issprinklered. If only one com-partment is sprinklered, therequirements must be met.

If the fire compartments are inseparate buildings, on opposite

sides of a firewall, the require-ments still apply even when oneor both of the buildings or compartments are sprinklered.

Soffits

[3.2.3.15.(1)] NBCC requirementsfor the protection of soffits limitopenings in overhanging roof soffitswhere an unprotected window orexterior door opening is less than2.5m below the soffit.

This requirement applies only in residential and certain insti-tutional occupancies where acommon attic or roof space islocated above more than twodwelling units or patients' bed-rooms. It is intended to impedethe spread of fire from one suite


Fire Compartment Alimiting distance

D = 6m

Fire Compartment Blimiting distance D = 3m

Do

Exposed Face

Interior FireSeparation

φ = 120°

Notes:1. Fire-resistance rating of exposed face within the distance Do must be at least equal to that of the interior fire separation.2. No openings are permitted within the distance Do

FIGURE 7.8

Separation ofopenings inexterior walls

D0 ≥ 2Dmax - [φ/90 × Dmax]

D0 ≥ 2(6) - [120/90 × 6]

D0 = 4m

through soffit openings to theroof space, and down into othersuites.

Materials that may be used to protect the soffit include:• 11mm plywood• 12.5mm oriented strandboard

or waferboard• 11mm lumber• any noncombustible material

at least 0.38mm thick having amelting point of at least 650°C

The soffit protection must extendon either side of the wall openingbelow (Figure 7.9).

The requirements for soffit protection are waived if:• the roof overhang is fire

stopped from the remainder of the roof space [3.2.3.15.(3)]

• the compartment containingthe window and door openingsis sprinklered [3.2.3.15.(4)]

The applicable sprinkler installa-tion standards, NFPA 13 and

NFPA 13R, permit certain roomssuch as closets and bathrooms to be unsprinklered. However, thoserooms must be sprinklered, to permit protection of the soffit to be waived.

VERTICAL FIRE SPREADBETWEEN FLOORS

SkylightsBuildings with portions havingdifferent building heights canpresent a potential for fire spreadwhere two fire compartmentsmeet at different elevations.

[3.2.3.14.] The location of skylights in the roof assembly of the lower portion of a buildingis restricted when there are openings in the adjacent exteriorwall of the higher portion. Theprovision of sprinkler protectionin the lower portion reduces thepotential for a severe fire and consequently allows unrestricteduse of skylights (Figure 7.10).

FIGURE 7.9

Protection of soffits


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1.2m

Suite

Soffit Vent

SuiteSuite

Protected Soffit(no openings)

Attic common to more than two suites

1.2m1.2m 1.2m

1.2m1.2m

Window OpeningsThe NBCC recognizes the potential for fire spread storey to storey through openings inexterior walls of commercial andindustrial buildings (Group E andGroup F, Divisions 1 & 2) due tothe substantial fire load usuallycontained in such buildings.

Once the fire has breached anopening in the exterior wall of astore or factory, flames projectingfrom that window could leapupward through an opening toanother compartment.

[3.2.3.16.(1)] For unsprinkleredbuildings, the NBCC requiressuch openings in the exteriorwalls of fire compartments to beseparated by a horizontal canopy.This canopy must:

• be at least 1m deep• have the same fire resistance

as the floor assembly, but neednot be more than one hour

Alternatively, the upper exteriorwall may be recessed at least 1m behind the exterior wall containing the opening in thelower storey.

In the previous edition of theNBCC, a vertical apron/spandrelor a canopy was considered acceptable protection againstpotential fire spread storey tostorey. In the 1995 NBCC, thisapron/spandrel option no longerapplies. Recent fire research andfire loss experience has shownthat even a 1m noncombustiblevertical spandrel between thewindows will not prevent storey tostorey fire spread.

FIGURE 7.10

Separation of windowopenings andskylights


If "D" is less than 5m, no windows are permitted in this area.

If "D" is 5m or more, there is no restriction on windows in adjacent wall of upper compartment.

Skylight

Unsprinklered fire compartment. If compartment is sprinklered, location of skylight or windows is unrestricted.

5m

5m

D

(Source: Commentary on Part 3 of National Building Code of Canada 1995, National Research Council Canada)

[3.2.3.16.(3)] In the previous edition of the NBCC, theapron/spandrel or canopy wasrequired in all affected buildings.It now has been recognized that, if a building is sprinklered, the exposure is reduced and thecanopy/setback requirements need not apply.

Since most multi-storey commercialand industrial buildings are nowrequired to be sprinklered, thecanopy or setback is only requiredin unsprinklered commercial andindustrial buildings two or threestoreys in height.

FIRE EXPOSURE OF EXIT FACILITIES

An exterior exit facility can beexposed unexpectedly to fire fromexterior wall openings in a num-ber of ways. Protection againstthis fire exposure can be providedfor the openings by one of threemethods of protection.

[3.2.3.12.(4)] The methods of protection accepted in the NBCCinclude:• glass block• wired glass• closures

[3.2.3.12.(1)[&](3)] Openings inclose proximity to each othermust be protected when they arein walls where the angle is 135° or less between:

• the exterior wall of a buildingand the exterior wall of an exit enclosure

• the exterior wall of one firecompartment and an exteriorwall of another fire compart-ment containing an exit door

Although not explicitly stated,where an opening in an exteriorexit enclosure is exposed, protec-tion is required only if the otheropening is in a different fire compartment.

This also applies for an exposedexterior exit door; protection isrequired only if the other exterioropening is located in a separatefire compartment.

[3.2.3.12.(1)] If an unprotectedopening in the exterior wall of an exit enclosure (other than an exterior exit door) could beexposed to fire from an unprotect-ed opening in the exterior wall of the same building, one of theopenings must be protected by one of the methods of protectionnoted previously (glass block,wired glass or closures).

This applies only if any portion ofthe opening in the exit enclosureis within 3m horizontally and lessthan 10m above or 2m below anyportion of the opening in the exterior wall of the building.

[3.2.3.12.(3)] If an exterior exitdoor is within 3m horizontally of an unprotected opening in the exterior wall of another firecompartment, the opening in theexterior wall must be protected by one of the methods of protec-tion.


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[3.4.4.3.(1)] Neither requirementfor the preceding two cases appliesto an exterior exit passagewaythat:• has not less than 50% of the

exterior sides open to the outdoors

• is served by exit stairs at eachend of the passageway

An exterior unenclosed exit stairor ramp could constitute a thirdcase of exposure.

[3.2.3.12.(2)] The exterior exitstair or ramp is consideredexposed only if any portion of it iswithin 3m horizontally and lessthan 10m above or 5m below anyportion of an opening in the exte-rior wall of the same building.

Under these conditions, the opening must be protected withone of the methods of protection.


The following are examples oflimiting distance calculationsand the construction optionsavailable for designing structuresin proximity to a property line.

EXAMPLE 7.1

Figure 7.11 (pg 253) shows a verysimple building arrangement:

Building height: one storeyOccupancy: Group A, Div. 2(restaurant)Sprinkler Protection: noneBuilding Position: walls parallel to the lot lines.Distance to lot line: South-3m,West-2mHeight of exposing building face: H = 3mLength of sides: L1 = 15mL2 = 9mArea of unprotected openings: South Side = 13.2m2

West Side = 2.4m2

Determine:

• whether the limiting distanceis sufficient on the South andWest sides

• the type of construction requiredfor these two exterior walls

[3.2.2.28.] In applying Subsection3.2.2 requirements, the construc-tion of the walls can be unratedwood frame construction.

Determining Limiting Distance

South SideThe minimum limiting distancerequired on the South side is

determined using the followinginformation:

Area of exposing building face: Aebf = L x H = 15 x 3 = 45m2

Area of unprotected openings: Aupo = 13.2m2

Ratio of length to height of firecompartment:

L/H = 15:3 = 5:1

Actual percentage of unprotectedopenings:

Aupo/Aebf = 13.2/45 × 100 = 29.3%

Solution:

[TABLE[3.2.3.1.A.] Given this per-centage of unprotected openings,the NBCC requires a limiting distance, D1, of 3.9m (by interpola-tion). This exceeds the limitingdistance, 3m, actually provided for this side of the building.

Since the distance to the lot line, S1,is only 3m, there are several options:• reduce the amount of unprotected

openings to 19% as required for alimiting distance of 3m

• use wired glass or glass blocksin the openings

• move the location of the building back 0.9m so that theactual distance from the lotline is 3.9m

By using wired glass or glass blocksin the windows, the area of permit-ted unprotected openings can bedoubled to 38%, well above the valuedesired by the owner.

Examples of Spatial Separation Calculations 251

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7.6 Examples of Spatial Separation Calculations

The option chosen will be dictated by:• economics• whether or not the owner wants

to keep all the windows in theSouth wall

• whether or not the distance tothe lot line on the North sidemust be maintained

West SideThe minimum limiting distancerequired on the West side isdetermined using the followinginformation:

Area of exposing building face:Aebf = L x H = 9 x 3 = 27m2



L/H = 9:3 = 3:1


Aupo/Aebf = 2.4/27 x 100 = 8.9%

Solution:

[TABLE[3.2.3.1.A.] Given this per-centage of unprotected openings,the NBCC requires a limiting distance, D2, of 1.5m (by interpola-tion). This is less than the 2m limiting distance, actually provid-ed for this side of the building.

The owner could increase the area of the windows on the West side to12.6 % or 3.4m2 and still be withinthe allowed limits for a 2m limitingdistance.

Determining Exterior WallConstruction Requirements

South WallThe option selected to meet the limiting distance requirements forthe South wall, will determine thetype of construction required forthe wall.

Option S7.1A:Limiting Distance — 3mWindow Type — ordinaryMaximum permitted area of unprotected openings — 19 percent

[3.2.3.7.(2)] Wall ConstructionRequirements:• can be wood frame construction• must have one-hour

fire-resistance rating (FRR)• must be clad with noncom-

bustible cladding

Option S7.1B:Limiting Distance — 3mWindow Type — wired glass orglass blockMaximum permitted area ofunprotected openings — 38 percent

[3.2.3.7.(2)] Wall constructionrequirements are the same asOption S7.1A.

[3.2.3.11.] The doubling of the 19% permitted openings for a limiting distance of 3m does notaffect the type of constructionrequired.


Option S7.1C:Limiting Distance — 3.9mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 29%

]3.2.3.7.(3)] Wall ConstructionRequirements:• can be wood frame construction• must have 45 minute FRR• can be clad with wood siding

West Wall

Option W7.1A:Limiting Distance — 2mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 12.6%

]3.2.3.7.(2)] Wall ConstructionRequirements:

• can be wood frame construction• must have one-hour FRR• must be clad with noncom-

bustible cladding

Option W7.1B:To lower the one-hour fire-resistancerating and avoid the need for non-combustible cladding, the ownerwould have to relocate the buildingto make the limiting distance to theWest wall at least 3.1m.

Limiting Distance — 3.1mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 26.6%

[3.2.3.7.(2)] Wall ConstructionRequirements:• can be wood frame construction• must have 45 minute FRR• can be clad with wood siding


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FIGURE 7.11

LimitingDistances — Examples 7.1 and 7.2

North

S2

S1

D2

L2

D1

L1

Lot LineLot Line

Avoiding Fire Rated Exterior WallsIf the owner wanted to avoid havingto provide fire-resistance ratingsfor the walls, the limiting distancesfrom these walls would have to be:

[TABLE[3.2.3.1.A.]

South Wall = 8m

West Wall = 7m

If firefighting facilities could not reach the building within 10minutes, the minimum limitingdistances would have to be doubledin order to avoid the fire-resistanceratings because the building isunsprinklered.

EXAMPLE 7.2

Same building as example 7.1 but building is sprinklered. Therequirements and options avail-able change significantly for a sprinklered building.


South SideThe minimum limiting distancerequired on the South side isdetermined using the followinginformation:



Ratio of length to height of firecompartment: Not applicable


Aupo/Aebf = 13.2/45 x 100 = 29.3%

Solution:

[TABLE[3.2.3.1.C.] Given this per-centage of unprotected openings,the NBCC requires a limiting dis-tance, D1, of 2.6m (by interpolation).This is less than the 3m limiting distance actually provided for this side of the building.

The amount of unprotected openings permitted for the 3mlimiting distance is actually 38%.The area of the openings could beincreased to this amount withoutaffecting limiting distance orwall construction.

West SideThe minimum limiting distancerequired on the West side is determined using the followinginformation:



Ratio of length to height of firecompartment: Not applicable


Aupo /Aebf = 2.4/27 x 100 = 8.9%

Solution:

[TABLE[3.2.3.1.C.] Given this per-centage of unprotected openings,the NBCC requires a limiting distance, D2, of 0.7m (by inter-polation). This is less than the 2m limiting distance actually provided for this side of the building.


[3.2.3.5.] The NBCC requires thatwhen the limiting distance is lessthan 1.2m, any openings in the wallmust be protected by closures otherthan wired glass of glass block.Consequently if the building ismoved to within 0.7m of the propertyline, protective measures must beprovided for the openings.


South SideUnlike the unsprinklered case,where the increased allowance inunprotected openings due to theuse of wired glass or glass blockdid not affect the minimum construction requirements, theincreased allowance in openingsdue to sprinklering of the buildingis used to determine minimumconstruction requirements.

Option S7.2A:Limiting Distance — 3.0mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 38%


West SideOption W7.2A:

Limiting Distance — 2mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 25.2 %


If the building is moved closer to the lot line, the exterior wallconstruction will be affected.

Option W7.2B:Limiting Distance — 0.7mWindow Type — Protected by closures other than wired glass or glass blockMaximum permitted area ofunprotected openings — 0%

[3.2.3.7.(1)] Wall ConstructionRequirements:• noncombustible construction• one-hour fire-resistance rating• clad with noncombustible

cladding

Option W7.2C:Limiting Distance — 1.2mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 15.2%

[3.2.3.7.(3)] Wall ConstructionRequirements:• can be wood frame construction• must be one-hour FRR• must be clad with noncom-

bustible cladding


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EXAMPLE 7.3

Figure 7.12 shows a more complexbuilding arrangement. The lot lineruns at an angle and comes veryclose to the North-West corner. Thebuilding also features a recessedwall on the West side.

Building height: one storeyOccupancy: Group A, Div. 2(restaurant)Sprinkler Protection — noneBuilding Position: walls not parallel to the lot lines, withrecessed sectionsDistance to lot line: North-2m West: • 1m (At the North-West

corner)• 6.7m (At wall section L4)

Height of the exposing buildingface: H = 3m

Length of sides: L1 = 12.5m

L2 + L3 + L4 = 10m

Area of unprotected openings: North Side = 8m2

West Side = 8.5m2

(including the door)

Determine:• whether the limiting distance

is sufficient on the North andWest sides

• the type of constructionrequired for these two exteriorwalls

[3.2.2.28.] As for Example 7.1, theconstruction of the walls can beunrated wood frame construction.


North SideThe minimum limiting distancerequired on the North side isdetermined using the followinginformation:

Area of exposing building face:Aebf = L x H = 12.5 x 3 = 37.5m2

Area of unprotected openings: Aupo = 8m2


L/H = 12.5:3 = 4.2:1


Aupo/Aebf = 8/37.5 x 100 = 21%

Solution:

[TABLE[[3.2.3.1.A.] Given this percentage of unprotected openings, the NBCC requires a limiting distance, D1, of 3.1m(by interpolation).

However, the distance to the lotline must be measured from thepoint where it is closest to theexposing building face, S1, whichis 2m. For this limiting distanceof 2m, the percentage of unpro-tected openings permitted in theNorth wall is only 11%.

Since the distance to the lot line,S1, is only 2m, additional protec-tion must be provided. There areseveral options:• reduce the amount of

unprotected openings to 11% as required for a limiting distance of 2m


• use wired glass or glass blocksin the openings to double theamount of permitted unprotect-ed openings to 22 percent, (justabove the value desired)

• move the location of the building back 1.1m so that the limiting distance is 3.1mwhich allows the 21% desiredunprotected openings


Area of exposing building face:Aebf = (L2 + L3 + L4) x H = 10 x 3 = 30m2



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L1

L2

North

Lot LineLot Line

D2

L3

L4

L5

S2

S1

D2

D2

D1

FIGURE 7.12

Limiting distances —Examples 7.3 and 7.4


L/H = 10:3 = 3.3:1


Aupo/Aebf = 8.5/30 x 100 = 28.3%

Solution:

[TABLE[3.2.3.1.A.] Given this per-centage of unprotected openings,the NBCC requires a limiting dis-tance, D2, of 3.3m (by interpolation).

The distance to the lot line must bemeasured from the point where it isnearest to any portion of the expos-ing building face, S2, which is 1m.On this basis, the entire exposingbuilding face can have no unprotect-ed openings because any openingwithin 1.2m of a lot line must beprotected by closures, other thanglass blocks or wired glass.

Since the distance to the lot line,S2, is only 1m, additional protec-tion must be provided. There areseveral options:• reduce the amount of actual

unprotected openings to 0, asrequired for a limiting dis-tance of 1m

• remove the windows from section L2 of the wall

• move the location of the buildingback 2.3m so that limiting dis-tance at the North-West corner is3.3m which allows the 28.3%desired unprotected openings


North Wall

Option N7.3A:

Limiting Distance — 2m

Window Type — ordinary

Maximum permitted area ofunprotected openings — 11%

[3.2.3.7.(2)] Wall ConstructionRequirements:• can be wood frame construction• must have one-hour FRR• must be clad with

noncombustible cladding

Option N7.3B:Limiting Distance — 2mWindow Type — wired glass orglass blockMaximum permitted area ofunprotected openings — 22%

[3.2.3.11.] Wall constructionrequirements are the same asoption N7.3A. The doubling of the11% permitted openings becausethey are protected by wired glassor glass block does not affect thetype of construction.

Option N7.3C:Limiting Distance — 3.1mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 21%


[3.2.3.7.(3)] Wall ConstructionRequirements:

• can be wood frame construction

• must have one-hour FRR

• must be clad with noncombustible cladding

West Wall

Option W7.3A:Limiting Distance — 1m

Window Type — Must have closures other than wiredglass or glass blockMaximum permitted area ofunprotected openings — 0%

[3.2.3.7.(2)] Wall ConstructionRequirements:• noncombustible construction• one-hour FRR• clad with noncombustible

cladding


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L1

L2

North

Lot LineLot Line

L3

L4

L5

S2

S1

S3

Projected vertical plane from which thepercentage of unprotected openings

permitted in L3 and L4 can be determined.

D3

D1

FIGURE 7.13

LimitingDistances — Example 7.3Option W7.3B

The limiting distance to the sectionclosest to the lot line governs theconstruction type required. Thisconstruction type will apply to allwall sections, including thoserecessed further away from the lotline. Consequently, all three wallsections of the west wall must be ofthe same construction type andfire-resistance rating.

Option W7.3B:

[3.2.3.1.(4)] The NBCC permitsthe amount of unprotected open-ings to be calculated on the basisof a limiting distance measuredfrom a vertical plane located sothat there are no unprotectedopenings between the plane andthe line to which the limiting distance is measured.

With the openings removed fromwall section L2, the minimum lim-iting distance required for thatwall section on the West sidewould then be determined usingthe following information:

Area of exposing building face:Aebf = (L2 + L3 + L4) x H = 10 x 3 = 30m2



L/H = 10:3 = 3.3:1


Aupo/Aebf = 5.4/30 x 100 = 18%

Solution:[TABLE[[3.2.3.1.A.] Given this percentage of unprotected openings,the NBCC requires a limiting dis-tance, D3, of 2.6m (by interpolation).

This is less than the 5.3m distance(S3) provided. Consequently, theunprotected openings in sections L3

and L4 can remain. (Figure 7.13)

The maximum percent of unpro-tected openings is expressed as apercentage of the area of theentire exposing building face. The total area of unprotectedopenings allowed can be placed in the smaller wall sectionswhich are set back.

However, the construction require-ments of Option W7.3A would stillapply to all the wall sections eventhough the unprotected openingswere removed from the sectionclosest to the lot line.

Option W7.3C:

The building is moved back 2.3m.We now have:

Limiting Distance — 3.3mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 28.3%


If, as described in Options N7.3Cand W7.3C, the building is moved2.3m back from the West lot lineand 1.1m further from the Northboundary, the original minimumlimiting distances required aremet and the original designcould stand.

Figure 7.14. shows the effect ofsuch a relocation.


EXAMPLE 7.4

Same building as example 7.3 but building is sprinklered. Therequirements change significant-ly for a sprinklered building.


North SideThe minimum limiting distancerequired on the North side is

determined using the followinginformation:

Area of exposing building face:Aebf = L x H = 12.5 x 3 = 37.5m2

Area of unprotected openings: Aupo = 8m2

Ratio of length to height of firecompartment: not applicable


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L1

L2

North

Lot LineLot LineLot Line

L3

L4

L5

S2

S1

D2

D1

FIGURE 7.14

Limiting distances — Example 7.3Option W7.3Cand N7.3C


Aupo/Aebf = 8/37.5 x 100 = 21%

Solution:[TABLE][3.2.3.1.C.] Given this per-centage of unprotected openings,the NBCC requires a limiting dis-tance, D1, of 1.9m (by interpolation).This is less than the 2m actual dis-tance to the lot line at the worstlocation, the North-West corner.


Area of exposing building face: Aebf = (L2 + L3 + L4) x H = 10 x 3 = 30m2


Ratio of length to height of firecompartment: not applicable


Aupo/Aebf = 8.5/30 x 100 = 28.3%

Solution:[TABLE][3.2.3.1.C.] Given this percentage of unprotected openings, the NBCC requires a limiting distance, D1, of 2.2m (by interpolation).

Like the unsprinklered case, thedistance to the lot line must bemeasured from the point where it is nearest to any portion of theexposing building face, S2, which is1m. This building face can have no

unprotected openings because anyopening within 1.2m of a lot linemust be protected by closures, otherthan glass blocks or wired glass.


North Wall

Option N7.4ALimiting Distance — 2.0mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 21.5%

[3.2.3.7.(3)] Wall ConstructionRequirements:• can be wood frame construction• must have one-hour FRR• must be clad with noncom-

bustible cladding

[3.2.3.11.] The doubling of the percent of unprotected openingsfor wired glass or glass block usedoes not apply in sprinkleredbuildings.

The provision of sprinklers in thisbuilding allows the desiredamount of unprotected openingswithout having to increase thelimiting distance. No otheroptions need be considered for this wall.

West Wall:

Option W7.4A:Limiting Distance — 1mWindow Type — Must have closures other than wired glassor glass block


Maximum permitted area of unprotected openings — 0% (actual)11.7% (for determining wallconstruction)

The 11.7% is determined by interpolation. Even with a limiting distance of less than 1.2m,sprinkler protection reduces theconstruction requirements.

[3.2.3.7.(2)] Wall ConstructionRequirements:• can be wood frame construction• must have one-hour FRR• must be clad with noncom-

bustible cladding

The limiting distance is less than 1.2m and therefore no actual unprotected openings are allowed. Constructionrequirements however are determined based on the percentage of openings thatwould be permitted. The use ofsprinklers results in the percentof permitted unprotected open-ings exceeding 10 percent. As aconsequence the minimum con-struction requirements change.

Option W7.4B:If the unprotected openings areremoved from L2, the limiting distance becomes 2.6m, D3.

Limiting Distance — 2.6mWindow Type — OrdinaryMaximum permitted area ofunprotected openings — 36.4% (actual) 11.7% (for determining wallconstruction)

[3.2.3.7.(2)] Wall ConstructionRequirements:• can be wood frame construction• must be one-hour FRR• must be clad with noncom-

bustible cladding

[3.2.3.1.(4)] The maximumamount of unprotected openingspermitted, 36.4%, is calculated onthe basis of a limiting distancemeasured from the vertical plane located so that there are nounprotected openings between theplane and the line to which thelimiting distance is measured.

The construction requirements of Option W7.4A would still apply to all the wall sections. The construction is based on thesmallest limiting distance anddoes not change based on the location of the openings.

Option W7.4C:To retain the original design, thesprinklered building would onlyneed to be located 2.2m from theWest lot line, instead of the 3.3mfor the unsprinklered case, and nofurther away from the Northboundary.

Limiting Distance — 2.2mWindow Type — ordinaryMaximum permitted area ofunprotected openings — 30%



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Chapter SummaryThe potential for fire spread between buildings increases significantly with proximity and the number of openings in exterior walls from which thermal radiation emanates.Adjacent properties can be protected if sufficient distances betweenbuildings are maintained or the number and size of openingsthrough which radiation is emitted is limited.The NBCC details calculation procedures and tables which establish distances and percentages of unprotected openings.The role of automatic sprinklers in reducing fire spread frombuilding to building is also reflected. New spatial separation tablesfor sprinklered buildings significantly reduce construction, limit-ing distance and unprotected opening requirements compared tothose for unsprinklered buildings.

8Fire Safetywithin Floor Areas8.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

8.2 Occupant Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

8.3 Fire Alarm and Detection Systems . . . . . . . . . . . . . . . . . . . . . 273

Alarm Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

Fire and Smoke Detection Systems . . . . . . . . . . . . . . . . . . . . . . 276

Signal to Fire Departments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

8.4 Means of Egress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

Suites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

Access to Exits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

Exits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

8.5 Safety within Floor Areas of

Specific Occupancies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

Assembly Occupancies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

Residential Occupancies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

Care Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

Repair and Storage Garages . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

8.6 Service Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299

Previous chapters have explainedthat the spread of fire can be controlled by:• limiting the combustibility

and flammability of buildingcomponents

• providing automatic sprinklerprotection

• providing physical barriers tocontain the fire

However, the immediate safety of building occupants depends primarily on:1. how quickly they are alerted

to a hazardous situation2. the means of escape available3. the degree to which those means

of escape offer protection fromlife-threatening conditions

The Manage Exposed branch ofthe NFPA Fire Safety ConceptsTree offers two alternatives:Safeguard Exposed and LimitAmount Exposed (exposed beingpeople).

Limiting the number of peoplethat might be exposed to a fire isan administrative responsibilitygoverned by the National FireCode of Canada (NFCC).

The Safeguard Exposed branchrelies on means to:• Defend Exposed in Place, or • Move Exposed

The Defend Exposed in Place concept applies particularly toinstitutions such as prisons, hospitals and nursing homeswhere mobility is restricted. Ifthe occupants cannot be easilymoved away from the hazard,

special safeguards must be inplace for them to safely remain in the vicinity.

The Move Exposed branch appliesto situations where occupants arealert and mobile, and can easilybe moved to a safe destination. Allthree steps in the Move Exposedbranch, (Figure 3.1), must be fol-lowed to achieve its objective:

1. Cause Movement of Exposed

2. Provide Movement Means

3. Provide Safe Destination

In other words, occupants must bealerted to the danger, must havemeans of egress and must have asafe destination.

This chapter describes the prin-ciples behind NBCC require-ments that provide for the safemovement of building occupantsduring a fire. Access for firefight-ing is an important part of firesafety within floors but isdescribed separately in Chapter 9.

The role of the firefighter isimportant to the safety of theoccupants in a fire situation.Firefighters can help occupantsto evacuate efficiently. In addi-tion, many building fire alarmsystems help fire departmentslocate a fire quickly, thereby aiding firefighters’ efforts to protect occupants.

As seen in Chapter 4, fire safetyrequirements for the overallbuilding are based on the build-ing’s major occupancy. NBCCrequirements for safety withinfloor areas, related to means ofegress, are based on the specific

The NBCC specifies exitrequirements


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occupancy of the floor area, roomor space being considered. Forexample, an office buildingclassed as a Group D major occupancy may contain a smallemployee cafeteria. Fire safetyrequirements for a cafeteria are not the same as those for anoffice, and therefore will beapplied separately.

Requirements for service spacesare also discussed. These areas are treated separately becausethey are usually unoccupied andinaccessible to the public or tobuilding occupants.


In planning exit facilities, and indetermining the need for a firealarm system, the first considera-tion is: How many people need tobe moved through the exit system?

A door can only allow a certainnumber of people to pass throughin a given amount of time. If alarge number of building occu-pants must funnel through onedoor, a queue, or lineup, will result.

Studies show that under the psychological stress imposed byan emergency, a queue will makecrowd control more difficult andcause people to panic. This canbecome a dangerous situation.

A sufficient number of appropri-ately sized exits must be providedto allow complete evacuation in areasonable amount of time. Inaddition, the choice of alarm system to provide detection andearly warning of a fire shouldtake into consideration thenature of the occupants, (forexample, mobility, age, number,and location in the building).

In unsprinklered buildings, theneed for a fire alarm system andthe number and size of exitsrequired to safely evacuate alloccupants in a space is based onthe number of people using thefacility. This number is called theoccupant load.

Occupant load is defined as: “the number of persons for whicha building or part thereof isdesigned.”

Occupant loads are used strictly fordetermining fire safety require-

ments and should not be confusedwith dead loads or live loads usedin design of structural members.

[3.1.16.1.] The NBCC assigns values, based on observations, tocalculate the number of peoplethat can reasonably be expectedto occupy a space for a specifiedpurpose. The values in NBCCTable 3.1.16.1. give the area insquare metres per person for common uses. There are twoexceptions to this:

• for rooms or space with fixedseats, the number of seats is used to determine the occu-pant load

• for dwelling units, the occupant load is based on twopersons per sleeping room

To calculate the number of people,or occupant load, a designer mustfirst determine the total floorarea that can be utilized. The following areas are not includedwhen determining occupant load:

• interior walls and partitions

• vertical shafts

• washrooms

• service rooms

• exits

The occupants of the floor area arethose using the washrooms, and soto include the washrooms wouldmean counting them twice. Servicerooms such as small electricalrooms are excluded as they are usu-ally unoccupied and when occupied,it is often by a person or personsalready calculated in the occupantload for the general floor area.

Occupant Load 269

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8.2 Occupant Load

Once the area of the room orspace is determined, it is thendivided by the value in NBCCTable 3.1.16.1. for the occupancytype to obtain the occupant load.This occupant load is then usedto determine the requirementsfor an alarm system, and thenumber and size of exits. Alarmsystems can also be required forreasons other than occupant load.These are detailed in section 8.3

The values in Table 3.1.16.1. shouldbe used only for determining exitand alarm requirements. Theyshould not be used to determineroom sizes or area required toaccommodate a specific number ofpeople. These numbers are intendedto determine the maximum possiblenumber of people that the exitscould be required to serve. Thesenumbers do not correspond with thearea that should be designed foroccupant use. Other architecturalmethods exist for determiningareas required for occupants.

The improper application of unitarea per person can lead to unsafeconditions, particularly in reha-bilitation projects where a spaceis converted to a new occupancy with a much lower area per per-son. The new value should be usedonly to assess exit capacity.

[3.1.16.1.(1)(c)] The NBCC doesgive some discretion to theauthority to approve differentoccupant load values where theowner can show that fewer personswill occupy the area. For example,a supper club might be designedwith a large dance area and wide-ly spaced tables. Since those usingthe dance area are presumablythose occupying the tables, thedance area could be excluded fromthe area calculation for determin-ing occupant load. The authorityhaving jurisdiction could then besatisfied that the occupant load isless than otherwise calculatedusing the assigned values.


FIGURE 8.1

Number andcharacteristicsof occupantsdeterminedesign standards

NBCC values are only providedfor common uses. For specialdesigns or occupancies not includ-ed in Table 3.1.16.1. of the NBCC,an occupant load can usually bedetermined jointly between thedesigner and the local authority.

[3.1.16.1.(4).] Where a room servesmore than one purpose, the occu-pant load must be determinedbased on the use involving thehighest density of occupants. Anassembly floor area, for example,may be used at different times for :

• non-fixed seating

• standing space

• dining or other purposes

For such multipurpose use, the calculation is based on the small-est number of square metres perperson, or highest density, in theTable for any of the multi-purposeuses. In this case, the value forstanding space would have to beused for determining occupantload.

Occupant Load 271

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The Move Exposed objective ofthe NFPA Fire Safety ConceptsTree relies on the successfulimplementation of several steps.The first step is Cause Movementof Exposed, which means that thebuilding occupants are alerted tothe existence of a fire. The mainmethod of achieving this is bymeans of a fire alarm system.

ALARM SYSTEMS

The provision of a fire alarm system depends primarily on:• the major occupancy

classification• occupant load• building size• whether the building is

sprinklered

[3.2.4.1.] Generally, the NBCCrequires a fire alarm system inall sprinklered buildings and inall buildings containing overthree storeys, including storeysbelow grade. The storeys belowgrade are included because firescan develop there undetected, andmay have fuel and occupant loadscomparable to other storeys.

In residential occupancies, analarm system is generallyrequired in buildings havingsleeping accommodation of morethan 10 persons, or when locatedin a building containing morethan three storeys.

[3.2.4.1.(3)] An alarm system is notrequired in residential buildings,including hotels and motels, if:• each of the dwelling units or

suites is served by an exterior

exit facility leading directly to ground level

• it is not more than threestoreys in height

• for an apartment building, notmore than four dwelling unitsshare the same means of egress

Individual egress routes willreduce exit time. Exterior exitfacilities provide smoke-freeegress routes and also allowimmediate firefighting access.

[3.2.4.1.(2)] Other conditionswhere fire alarm systems arerequired include unsprinkleredbuildings which contain:• a contained use area • an impeded egress zone• a total occupant load more

than 300, other than in openair seating areas

• an occupant load more than 150above or below the first storey,other than in open air seatingareas

• an occupant load more than 300below an open air seating area

• a school, college, or child carefacility, including a day carefacility, with an occupant loadmore than 40

• a licensed beverage establish-ment or a restaurant, with anoccupant load more than 150

• a medium hazard industrialoccupancy or a low hazardindustrial occupancy with anoccupant load more than 75above or below the first storey

• a high hazard industrial occupancy with an occupantload more than 25

Fire Alarm and Detection Systems 273

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8.3 Fire Alarm and Detection Systems

Types of Fire Alarms

[3.2.4.4.] The NBCC specifies twotypes of fire alarm systems: • the single-stage system, in

which manually activated signalling boxes (pull stations)or other devices cause a generalalarm to sound throughout thebuilding

• the two-stage system, in whichthe activating device firstsounds an alert signal to warnthose on duty that an emer-gency exists before the generalalarm is given

The two-stage alarm allows super-visory staff to verify the nature ofthe emergency before initiatingevacuation. If the supervisory personnel do not respond to thealert signal within five minutes,the general alarm is automaticallyactivated. Manual pull stationsmust be equipped to allow for a general alarm signal to be initiated immediately, if so desired by supervisory personnel.

[3.2.4.3.] In Group B, care ordetention occupancies, where peopleare under restraint, or are other-wise restricted by age or infirmity,a two-stage alarm is required. Thisavoids initiating evacuation forwhat could be a false alarm.

The first stage or alert ensuresthat staff has an opportunity toinvestigate the emergency beforethe building is evacuated at thesound of the general alarm.However, a single-stage system ispermitted in children’s custodialhomes, convalescent homes andorphanages, provided the building

is not more than three storeys in height.

The fire alarm system in Group F,Division 1, high-hazard industrialoccupancies must be a single-stagesystem because of the need forprompt alarm and evacuation. Two-stage systems are not permitted inthis type of occupancy, since a firecould develop with such speed thatany delay in sounding a generalalarm might have life-threateningimplications.

In all other cases, where a firealarm system is required, it can be either a single stage or twostage system.

Continuity of Fire Alarm Systems

[3.2.4.2.] As a general principle,if a fire alarm system is requiredin any portion of a building, thesystem must serve the entirebuilding. This can even apply tobuildings that are considered separate buildings by the NBCCbecause they are divided by a firewall. The alarm must be pro-vided on both sides of the firewallonly if there are large openingsthrough it such as windows, doorsor HVAC ducts.

In multiple occupancy buildings,requirements for a fire alarm system serving each major occu-pancy may differ. Even if onlyone major occupancy in thebuilding requires an alarm sys-tem, the system must be designedto serve the entire building. Thesounding of the alarm in oneoccupancy must activate thealarm throughout the building.


This will alert all the occupantsof the building to the danger.

[3.2.4.2.(4)] The NBCC does makean exception to the continuity offire alarm systems for buildingswhich are:• up to three storeys in height • divided by vertical one-hour

fire separations through whichthere is no access from one por-tion of the building to another

[3.2.4.1.] This includes buildingssuch as row housing units andindustrial plazas or malls.

This exception is due to each suitehaving its own exits independentof others and travel distancesbeing short. In such cases, eachportion is permitted to be providedwith separate and independentfire alarm systems. This exceptiondoes not apply to buildingsrequired to be sprinklered.

Installation Requirements

[3.2.4.5.] Fire alarm systemsmust be installed and tested inaccordance with

• CAN/ULC-S524 Standard forthe Installation of Fire AlarmSystems

• CAN/ULC-S537 Standard forthe Verification of Fire AlarmSystems

Proper installation and ongoingmaintenance of fire alarm systemsare both vital. This ensures thatthe system functions properly andwill promptly alert building occu-pants to a fire.

Annunciator Panels

[3.2.4.8.(1)] In general, all build-ings which are required to besprinklered or required to have afire alarm system must be pro-vided with an annunciator panelto advise firefighters of the loca-tion of the fire. The panel mustbe located in close proximity to abuilding entrance that faces astreet or access route. If there ismore than one such entrance, apanel is required at only one ofthe entrances, preferably theentrance where fire departmentpersonnel are expected to enter.

[3.2.4.8.(5)] Annunciator panelsare not required for certain smaller buildings required tohave a fire alarm system when:• the aggregate area for all

storeys (including those belowgrade) does not exceed 2000m2

• the building is not more thanthree storeys in buildingheight

• the building is not sprinklered

In such cases, the requirement foran annunciator panel is waivedbecause, given the size of thebuilding, the location of the fireshould be readily obvious.

[3.2.4.8.(4)] When an annuncia-tor panel is not installed in abuilding required to have a firealarm system, the alarm systemmust be connected to a signaldevice which will give a visualand audible trouble signal toalert the occupants to a problemwith the system. This signaldevice must be located at themain entrance to the building.


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[3.2.4.8.(2)] Fire alarm systems inlarger buildings must be zoned.The annunciator panel must indi-cate the location of the alarmactivation for each separate floorarea or zone. No zone can exceed2000m2 in area.

[3.2.4.8.(6)] This area limit doesnot apply to interior undividedopen space used for an arena, rink,or swimming pool. In such cases,the entire open space can be onezone, while the remaining portionsof the building are still zoned forevery 2000m2 of area.

FIRE AND SMOKE DETECTION SYSTEMS

The effectiveness of a fire alarmsystem depends on how quickly itis activated after the outbreak of afire. If activation of the alarm sys-tem relies on manual pull stations,a significant amount of time couldelapse before the alarm is given tothe fire department because:

• the fire could be burning unde-tected in an unoccupied area, or

• occupants could fail to pull the alarm in their haste toevacuate the premises

Manual Pull Stations

[3.2.4.17.(1)] Manual pull stationsare required in most buildings in which a fire alarm system isinstalled. The stations must beinstalled:• near every required exit• near the principal entrance to

the building on any storeylocated at ground level

[3.2.4.17.(3)] In a building contain-ing a hotel or motel or only dwellingunits, pull stations are not requiredat exterior egress doorways from asuite or dwelling unit provided:• the building is not more than

three storeys in height• the building is sprinklered

• each suite or dwelling unit is served by an exterior exitfacility leading directly toground level

• the egress doorway does notlead to an interior sharedmeans of egress

[3.2.4.17.(4)] Manual pull stationsare required near any doorway lead-ing from a shared interior corridorto the exterior in the above cases.

Automatic Detection Requirements

Buildings requiring a fire alarmsystem also require some means ofautomatic fire detection, including:• heat detectors of either fixed

temperature or rate of rise • automatic sprinklers• smoke detectors

The value of fire detectors in savinglives is beyond doubt; precious timeis gained through early warning.They are particularly useful in:

• residential occupancies whereoccupants may be sleeping

• in hospitals and nursinghomes to initiate preplanningresponse by staff

• in areas such as storage lockerrooms and service rooms, wherea fire may gain considerableintensity before it is detected


[3.2.4.10.(2)] In unsprinkleredbuildings where a fire alarm isrequired, fire detectors connectedto the fire alarm system must beinstalled in specific areas. Theseareas are typically unoccupiedand often contain potential ignition sources and include:• storage and service rooms not

within a dwelling unit• janitor’s rooms• elevator and dumbwaiter shafts• laundry rooms not within a

dwelling unit

These fire detectors can be eithersmoke or heat detectors.

[3.2.4.11.] In buildings wherelarge groups gather or whereoccupants may sleep, smoke detectors are also required inthose vital areas such as:• sleeping rooms and egress

corridors from Group B• all public corridors in Group C • corridors in Group A Division 1

occupancies• exit stair shafts• rooms and corridors in a

contained use area • interconnected floor spaces

next to draft stops providedaround the floor openings

In these areas, a quick response isessential should a fire occur.

Many buildings have a mechanical ventilation systemthat recirculates air throughoutthe building through one or morecentral plenum chambers. Thesesystems can distribute smokefrom the origin of fire through-out the building.

Even a relatively small fire haspotential to contaminate an entirebuilding with smoke through anair circulation system. Smoke canbe sufficiently dense or toxic, evenwhen it is diluted, to impede evac-uation particularly when it is discharged into a means of egress.

[3.2.4.12.] For this reason, duct-type smoke detectors are ofteninstalled in recirculating air handling systems where a firealarm system is required for abuilding. Specifically, these detectors are required when theair handling system:• serves more than one storey• serves more than one suite

in a storey• serves more than one fire

compartment in floor areascontaining patient rooms in ahospital or nursing home

These smoke detectors initiate analarm which activates dampersand fan controls to shut down the equipment which prevents the distribution of contaminated air throughout the building.

Automatic Detection SystemsSeveral types of fire and smokedetection devices are available.The heat detector is designed tosense abnormally high tempera-tures or a high rate of temperaturerise. Its disadvantage is that itwill not necessarily detect asmouldering fire. A smoulderingfire can produce enough smoke tocause a hazard to life before suffi-cient heat builds up to activate the detector. On the positive side,heat detectors are reliable andneed little maintenance.


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Smoke detectors can detect thepresence of fire at a much earlierstage than heat detectors. Smokedetectors are activated by productsof combustion and will detect asmouldering fire.

There are two principal types ofsmoke detectors (Figure 8.2):• photo-electric smoke detectors

measure the amount of lightobscuration caused by the pres-ence of products of combustion

• ionization detectors react to areduction in conductance causedby the presence of products ofcombustion

Both types require periodic main-tenance.

Infrared and ultra-violet detec-tors respond to low-energy flamesand are most appropriate in areaswhere flammable liquids arestored.


FIGURE 8.2

Smoke detectors

+

-+

++

-

- -

Alarm OFF

+

-

Radioactive material(ion source)

+

-+++

-

- -

Alarm ON

+

-

Smoke particles makeions less mobile

Alarm ON

Alarm OFF

Light Source Receiver

Light Source Receiver

Clean Air

Smoke Particles

Photoelectric Detector

All of these heat, smoke and flamedetectors are designed to provide asignal to the building fire alarmsystem. The type most suitable fora particular floor area depends onthe physical characteristics of thehazard associated with the floorarea.

[3.2.4.21.] The NBCC requires asmoke alarm in all dwellingunits, and in any sleeping roomoutside a dwelling unit that isnot in a care or detention occu-pancy required to have a firealarm system. Thus every apart-ment and every bedroom inhotels, motels, dormitories andsimilar buildings must beequipped with a smoke alarm.

[3.2.4.21.(2)] In multi-storeydwelling units, at least one smokealarm is required to be installedon each storey. These smokealarms must be wired so that ifany one activates, all the alarmswill sound.

A smoke alarm differs from asmoke detector in that it is not connected to a fire alarm system,but is instead designed to act as aself-contained fire detector andalarm. It will warn occupants within a suite or dwelling unit ofa fire in time to safely exit thebuilding.

Smoke alarms are relatively inex-pensive and reliable, providedthey are tested and maintainedregularly to remove dust and otherairborne particles from cookingand smoking that become trappedin the detection chamber.

[3.2.4.21.(8)] The NBCC permits amanual disconnect device to beinstalled to allow disabling thesmoke alarm temporarily. Thispermits silencing the alarm inthe case of burnt toast withoutthe permanent disconnection ofthese critical alarms.

[3.2.4.15.] Automatic sprinklersare considered to fulfill therequirement for fire detectorsbecause they operate on the sameprinciple as fixed temperatureheat detectors.

High buildings are subject toadditional requirements for firealarm and detection systems,such as the provision of voice communication systems. Theseare discussed in Chapter 10, High Buildings.

SIGNAL TO FIRE DEPARTMENTS

The sooner a fire is detected andextinguished, the more lives canbe saved and the less propertydamage incurred. If a fire isdetected in its early stages, it canoften be controlled by portablefire extinguishers. It is difficult,however, to predict the severity ofa fire, and the fire departmentshould always be called as soon asa fire is discovered.

[3.2.4.7.] This is one reason whythe 1995 NBCC now requires thatall automatic sprinkler systems bedesigned to transmit a signal toautomatically notify the firedepartment that a waterflow detec-tion device has been activated.


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[3.2.4.9.(2)] All automatic sprin-kler systems must be electricallysupervised to ensure that anyimpairment or tampering withthe system will be detected.Electrical supervision ensuresthat an electrical signal will betransmitted to the annunciatorpanel if any of the following occur:• any valve controlling water

supply is moved• a pressure loss develops

(water flow)• the electrical supply to any auto-

matic fire pump system fails • the water supply becomes

inadequate• the temperature falls

sufficiently to cause part of the water supply to freeze

[3.2.4.7.] Single stage fire alarmsystems are not required to bedesigned to transmit a signal tonotify the fire department exceptin a building of assembly occu-

pancy having an occupant loadmore than 300. When the alarmsystem does not send a signal tothe fire department, a legiblenotice stating that the firedepartment be notified must beposted on the wall near each manual pull station.

Signals to the fire departmentmay be transmitted by:

• proprietary control centres conforming to Chapter 9 of NFPA Standard 72D,Installation, Maintenance and Use of ProprietaryProtective Signalling Systems

• a central station located off thepremises, usually monitored byan independent agency

Proprietary control centres aremonitoring stations located on theproperty which ensure constantsupervision. The alarm signalmay be transmitted to the firedepartment automatically ormanually via a supervised circuit.


Means of egress, including exitsand access to exits, is a major factor affecting life safety.

An exit is that part of a means ofegress which leads from the floorarea it serves to the outside orother safe destination. In otherwords, it is the final, most protectedlink between any part of the build-ing and a safe destination.

Theoretically, once occupants of abuilding enter an exit, they shouldbe protected from the threat of fireuntil they reach safety. Access toexits are those facilities within afloor area which lead from a suite,or from any part within a suite, tothe exit.

The NBCC requirements formeans of egress are intended tosatisfy steps two and three in theMove Exposed Branch of theNFPA Fire Safety Concepts Tree:• Provide Movement Means • Provide Safe Destination

SUITES

Before discussing access to exits, it isuseful to explain what constitutes asuite, since a number of access toexit requirements depend onwhether a floor area is occupied bya single tenant or several tenants.

A suite is a room or group ofrooms occupied by a single ten-ant. The rooms within a suitehave access to each other eitherdirectly by means of a commondoorway, or indirectly by an inte-rior corridor, by a vestibule or byother similar arrangement con-tained within the suite.

In the NBCC, it is irrelevantwhether the suite is rented orowned. It is important that a suitebe under the control of a singletenant. Thus, common laundryrooms or service rooms are notconsidered as suites.

Classrooms in a school, individualpatient rooms, or units such as amaternity ward in a hospital arenot considered suites either. Theybelong to a single owner, (theschool board or the hospital admin-istration), which normally has con-trol over those spaces. On the otherhand, areas individually rented orowned by different tenants in anapartment building, a hotel or anoffice building, are primarilyunder the control of those tenants,and one tenant normally has nocontrol over another tenant’s suite.

Should a fire occur in an unoccu-pied suite, occupants of neigh-bouring suites would not be awareof a fire until they could smellsmoke or were otherwise alertedto the existence of a fire; by then,the fire could be well developed.This underlines the importanceof installing fire detectors con-nected to an alarm system in eachsuite to alert all occupants of afire, and separating suites to helpcontain a fire.

The NBCC refers to suites androoms not located within a suite.This is intended to clarify that therequirement applies to:

• individual suites but not toeach room within the suite

• common rooms, such as laundry orservice rooms that are not underthe control of a single tenant

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8.4 Means of Egress

ACCESS TO EXITS

The “access to exits” concept isoften misunderstood. Access toexit refers to a path of travel fromany point on a floor area to anexit serving the floor area. Thisincludes:

• that part of an individualroom or suite which leads to an exit

• a doorway that leads to a publiccorridor or other shared meansof egress

• the path of travel from thesuite doorway to the exit whichcan include corridors, publiccorridors and passageways (Figure 8.3)

The access to exit portion locatedwithin a room or a suite is notsubject to specific requirementsother than:• it must provide an unobstructed

path of travel to an egress door-way [3.3.1.22.(1)]

• the distance from any point inthe room or suite to an egressdoorway must not exceed speci-fied limits depending on theoccupancy ]3.4.2.5.]

Specific requirements related tofire separations within occupan-cies and seating arrangements inassembly occupancies have animpact on access to exits becausethey affect the path of travel.Travel distance is measured alongthe path of travel from any pointin a floor area to the nearest exit(Figure 8.5).

Limits on travel distances areobviously important because ofthe potential for an occupant to beexposed to unsafe conditions beforereaching the safety of an exit.

Egress Doorways

[3.3.1.3.(8)] Generally, any floorarea containing more than onesuite requires only one egressdoorway from each individual


FIGURE 8.3

Typical accessfor floor areas

Individually rented suite(e.g., dwelling unit)

Exit Exit

ExitDoor

Egress Doorway(access to exit)

Typical floor area

Public corridor (access to exits)

suite. This single egress doorwayfrom the suite must be:

• an exterior exit doorway leading to the outside

• a doorway leading to a publiccorridor that provides access in opposite directions to twoseparate exits

• a doorway leading to an exteriorpassageway that is open to theoutdoors, and leads in oppositedirections to two separate exits

[3.3.1.5.] Except for dwellingunits, at least two egress door-ways must be provided if a roomor suite:

• is used for a high-hazard industrial occupancy and hasan area more than 15m2

• is intended for an occupantload of more than 60 persons

• has an area or the travel dis-tance from any point withinthe room or suite to an egress

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FIGURE 8.4

Corridors andclassroomdoorways provide accessto exit

doorway exceeding the valuesshown in Table 8.1 for anunsprinklered suite

• has an area which exceeds thevalue in Table 8.2, or the traveldistance within the room orsuite to an egress doorway ismore than 25m for a sprin-klered suite

To determine whether more thanone egress doorway is required froma room or suite, the maximum traveldistance is measured along the pathof travel from any point within theroom or suite to the nearest egressdoorway. Unless only one exit isrequired for the floor area, it isassumed that the egress doorways

TABLE 8.1

Egress in floorarea not sprinkleredthroughout

TABLE 8.2

Egress in floorarea sprinkleredthroughout


Occupancy of Maximum Area of Maximum Distance toRoom or Suite Room or Suite Egress Doorway

m2 m

Group A 150 15

Group C 100(1) 15(1)

Group D 200 25

Group E 150 15

Group F, Division 2 150 10

Group F, Division 3 200 15

Source: Table 3.3.1.5.A of the NBCC1. See Article 3.3.4.4. for dwelling units

Occupancy of Maximum Area ofRoom or Suite Room or Suite

m2

Group A 200

Group B, Division 1 100

Group B, Division 2sleeping rooms 100other than sleeping rooms 200

Group C 150(1)

Group D 300

Group E 200

Group F, Division 2 200

Group F, Division 3 300

Source: Table 3.3.1.5.B. of the NBCC1. See Article 3.3.4.4. for dwelling units

will open into a corridor or passage-way where it will be possible totravel in two different directions toseparate exits.

[3.3.1.6.] Once the number ofegress doorways required is deter-mined, the maximum travel dis-tances for exits are calculated.The maximum travel distanceswithin the room or suite to theegress doorways must not exceedthe limits set for maximum traveldistance for exits.

[3.3.1.5.] When two or moreegress doorways are required, thedoorways must be located as far as practicable from each other.This is so that in the event of a

fire, if one becomes inaccessible,at least one of the others can stillbe used. Exact dimensions forminimum distances between doorsare not provided since these willdepend on the design of the suite;judgement must be exercised ineach case.

[3.4.2.4.(1)] For an open floor areathat serves a single tenant, thetravel distance to an exit is mea-sured from any point on the floorarea to the nearest exit door(Figure 8.5). In a multi-tenantfloor area, travel distance to anexit is typically measured for eachtenant space from the most remotepoint in the room or suite throughthe corridor to an exit.

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FIGURE 8.5

Undivided floorarea

Exit

x

x

Travel Distance

Travel Distance

P

P

Maximum DiagonalDistance

Exit

Travel distance from arbitrary points within a floor area, such as points “P”, is measured along the path of travel to the nearest exit. The longest travel distance within a floor area must not exceed distance listed in Subsection 3.4.2. In addition, exits must be as far apart as practicable. Distance between exits must be 1/2 the maximum diagonal dimension of the floor area or 9m, whichever is greater.

[3.4.2.4.(2)] Travel distance to thenearest exit can be measured fromthe egress door of a suite or aroom not within a suite if it isseparated from the remainder ofthe floor area by: (Figure 8.6)

• fire separations with a fire-resistance rating of not lessthan 45 minutes, or

• by unrated fire separations ifthe floor area is sprinklered

[3.4.2.4.(2)] Egress doors mustopen onto• an exterior passageway• a public corridor• a corridor used by the public

[3.3.1.4.] The requirement for fireseparations between the corridorsand the remainder of the floorarea is dependent upon:• the occupancy• whether the floor area is

sprinklered• the width and, in some cases,

the height of the corridor

CorridorsTypically, an occupant leaving asuite enters a corridor which isshared with other tenants. Thesecorridors are designed to offer anarea of relative safety to enablethem to reach an exit. The NBCCcalls such corridors public corridors.


FIGURE 8.6

Public corridordivided fromfloor area by rated fireseparations

ExitTravel

Distance

Maximum DiagonalDistance

ExitTravel Distance

When a floor area has been subdivided by at least 45 minute fire separations to serve more than one tenant, the travel distance is measured along the path of exit travel within the public corridor from the door of the room or suite to the nearest exit. Again, the longest travel distance must not exceeddistances listed in Subsection 3.4.2. Also exits must be as far apart as practicable. The least distance between exit should be 1/2 the maximum diagonal dimension of the floor area, but need not exceed 9m.

Exit

Exit

Public corridors are defined as: “acorridor that provides access toexit from more than one suite”.

These should not be confused with“corridors used by the public”which serve institutional, assem-bly, and business and personalservices occupancies that do nothave multiple tenants.

[3.3.1.9.] The NBCC also regu-lates corridors serving patients’bedrooms or classrooms which maybe used by the public but are notdefined as public corridors. Theseare treated as special corridorsand are protected accordingly.

All corridors must be designed togive an occupant the option of twodirections to reach an exit in caseone route becomes unsafe. This isone of the most important tenets ofthe NBCC philosophy: an alterna-tive escape route should be availableunless it is deemed that occupantsafety will not be reduced by provid-ing a single exit route.

[3.3.1.9.(7)] For this reason, theuse of dead-end corridors isrestricted. However, the NBCCrecognizes that dead-end corridorsare sometimes necessary for theefficient utilization of space. TheNBCC permits dead-end portionsup to 6m with certain restrictions.Longer dead-end corridors areonly allowed in residential occu-pancies where a second means ofegress is available from the suite.

[3.3.1.4.] In most cases, the NBCCrequires that fire separations witha fire-resistance rating be providedbetween public corridors used foraccess to exits and the remainder of

the floor area. The fire-resistancerating requirement is waived butthere must still be a fire separa-tion if the floor area:• is sprinklered • does not contain a care or deten-

tion or residential occupancy

No fire separation is requiredwhen such corridors exceed 5m inunobstructed width as in the caseof enclosed malls. In such cases,the wide corridor along with themonitored and alarmed automaticsprinkler system, is deemed toprovide the necessary protectionagainst fire spread.

Other public corridors which serveas access to exits are also subject to:• minimum dimensions [3.3.1.9.] • lighting levels for normal and

emergency situations ]3.2.7.1.]• flame-spread limitations, as

discussed in Chapter 6 [3.1.13.6.]

[3.3.1.9.] The NBCC specifies minimum widths and headroomclearances for public corridors anddoorways used as an access to anexit. However, the capacity of exitsand access to exits depends onoccupant load. The requirementswhich regulate width on the basisof the occupant load served bythese facilities must govern, ifthese are more stringent.

In designing widths for access toexits, the likely direction of move-ment should be considered. In mostsituations, it is fairly predictablebut in complex arrangementsinvolving multiple egress paths,judgement must be exercised todetermine the occupant loadserved by a particular route.

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EXITS

[3.4.2.1.(1)] The NBCC requires (in most cases) that every floorarea be served by at least twoexits. The number and location ofexits will depend on:

• the occupancy

• the occupant load

• travel distances

[3.4.4.1.] Exits must lead to a safedestination and, except for a fewminor exceptions, must be sepa-rated by fire separations from theremainder of the floor area.

[3.4.2.3.] It is a NBCC principle,that a second exit must be accessiblein case the route to the first becomesimpassable. Minimum separationdistances are imposed in open floordesigns. In all cases, exits should belocated as far as practicable fromeach other (Figures 8.5 and 8.6).

[3.4.2.1.(2)] In small buildings ofnot more than two storeys in build-ing height, where travel distancesare short and occupant load is atmost 60, a single exit from a floorarea is permissible. This is consistentwith requirements for individualsuites where a single egress doorwayis acceptable for an occupant load ofup to 60 persons.

Exits should not be confused withaccess to exits, (previously discussed).An exit is not part of the floor area.It is a completely separate compart-ment which leads directly to:

• a separate building

• an open public thoroughfare, or

• an exterior open space which isprotected from fire exposurefrom the building and hasaccess to an open public thoroughfare

It should be remembered thatexits also serve regular traffic toand from floor areas. Designersoften provide exit facilities foreveryday use in addition to theones required by the building code.

These extra facilities serve a similar function as the requiredexits, but they are not required to meet NBCC requirements forexits. For example, pull stationsfor fire alarm systems may not becompulsory at such exits. It isgood practice, however, to adhereto the same regulations to avoidpossible confusion for occupants.

[3.4.6.] Certain design and build-ing requirements apply to exits.These requirements are intendedto reduce the possibility of injurywhen the facilities are used.Specifications governing featuressuch as direction of door swing,stair treads and risers, guards,handrails and ramp gradient areset out clearly in the NBCC.

Exit RequirementsThe NBCC requirements for thenumber and location of exits shouldbe taken into consideration in theinitial planning of a building.Introducing additional exit facili-ties at a later stage can prove costlyand disruptive

The first step is to determine theoccupant load for each floor. Next,the number of exits, location, and


details such as height, width and thefire-resistance rating of enclosingfire separations can be determined,based on occupancy, travel distancesand whether or not the floor area orbuilding is sprinklered.

[3.4.3.4.] The aggregate or totalcombined width of an exit or exitsserving a floor area is determinedby multiplying the occupant loadof the room or floor area by thenumber of millimetres of exitwidth required per person.

This approach to calculating exitwidths, based on a certain amountof space per person, replaces theformer step function approach usedpreviously in the NBCC. This givesdesigners more flexibility in sizingexit routes to accommodate theflow of occupants expected in anemergency. This approach is usual-ly used for exits which are requiredto exceed the minimum width.

[3.4.2.5.(3)] If more than one exitis required from a floor area, no sin-gle exit may be considered to con-tribute more than half of therequired exit width. This limitationensures that alternative escaperoutes have adequate exit capacityshould one exit become inaccessible.

The sequence to follow whendetermining exit requirements is:

1. Determine the number of exitsrequired based on travel dis-tance and other requirements.

2. Determine the minimum widthrequirements of the requiredexits to give an aggregate widthof these exits.

3. Establish the minimum aggre-gate exit width required to provide exit capacity for theoccupant load.

If 2 is greater than 3, the require-ments have been met. If 3 isgreater than 2, the width of theexits will have to be increased toprovide for the required width.

[3.4.3.1.] The clear width of everyexit is required to be at least900mm, with the exception of cer-tain fire escapes which need onlybe 550mm wide. The minimumwidth necessary for free travel ofa single file of people is consid-ered to be 550mm, but minimumexit widths are usually wideenough to allow for two files ofpersons, that is, 1100mm.

[3.4.3.4.] The aggregate width ofexits required from a floor area isdetermined by the occupant load.The required width varies withthe mobility of the occupants andthe hazard of the floor area served.

[3.4.3.5.] Exits should not narrowsuddenly. This can congest trafficand incite panic. A doorway lead-ing from an exit stairway or rampwill usually be narrower than thestairway or ramp. Sufficient spaceis necessary so that occupants canadjust to the different rhythms ofmovement on stairs or on a levelsurface. Exit width should not beblocked by turnstiles or construc-tion projecting into the exit. Doorhinges, swinging doors, handrailsor stair stringers are permitted toreduce exit width slightly.

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As noted, floor areas must bedesigned so that the allowabletravel distance to an exit is notexceeded. The NBCC stipulates(for most cases) that at least twoexits be provided from each floorarea. For large floor areas, morethan two exits might be requiredif maximum travel distances areexceeded.

[3.4.2.5.] Generally, maximumtravel distances are limited to arange of 25 to 40m, depending onoccupancy. However, in storagegarages with all storeys con-structed as open-air storeys andwith no other occupancy above, a travel distance of 60m is permitted because occupant load is limited.

[3.4.2.5.(1)] Travel distances up to 105m are permitted in sprin-klered buildings such as shoppingmalls, even though suites are notseparated from the public corridorby fire separations, provided:

• the public corridor is at least9m wide

• the ceiling of the public corri-dor is at least 4m high

• if a room or suite requires morethan one egress doorway, onlyone-half of the egress doorwaysopen into the public corridor

These longer travel distances arepermitted because sprinklers willhelp to control heat, the highceiling will act as a smoke reser-voir, and the large public corridorprovides ample exit capacity(Figure 8.7).

As previous chapters note, exitsrequire special protection:

• exits must be enclosed by fireseparations with a fire-resis-tance rating at least equal tothat of the floor assembly[3.4.4.1.]

• finish materials must have lowflame-spread ratings [3.1.13.2.]

• penetrations of the fire separa-tions which enclose exits mustonly accommodate building services that are necessary tothe exit [3.4.4.4.].

[3.4.5.1.] NBCC regulations formeans of egress constitute mini-mum requirements. Designersshould make every effort to ensurethe integrity of exits because theyconstitute the lifeline betweenfloor areas and the street. As well,exit routes, including those pro-viding access to exits, must beclearly marked with exit signs todirect occupants during a fire.


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FIGURE 8.7

Public corridornot dividedfrom floor areaby rated fireseparations

Travel Distance

Exit

Exit

Exit

Exit Exit

Exit

Exi

t pas

sage

way

Exi

t pas

sage

way

Public Corridor

9mMinimum

When a floor area is not subdivided by rated fire separations and is served by a 9m widepublic corridor, the travel distance is measured along the path of exit travel within the floor area.The maximum travel distance in this case is 105 m. Also, if more than one egress door isrequired from a room or suite, no more than 1/2of the egress doors may open into the public corridor. The building must be sprinklered, and ceiling height in the public corridor can not be less than 4 m.

There are a number of otherrequirements affecting safetywhich concern specific occupancies.

ASSEMBLY OCCUPANCIES

Requirements for assembly occupancies relate primarily to:

• the protection of these spacesfrom adjacent occupancies[3.3.2.2.]

• the detailed treatment of seat-ing arrangements to ensurethat egress will not be impededby inadequate aisles and exitcapacity [3.3.2.3]&[3.3.2.4]

The safety hazard of an assemblyoccupancy is the large number ofpeople gathered in a public placewith which they are not necessarilyfamiliar. The fire load due to thecombustible contents of an assem-bly occupancy is generally low. Thepotential hazard to safety is, how-ever, increased by the necessity ofrows of seating, tables and otherobstructions to movement thatrestrict direct access to exits acrossa floor area (Figure 8.8).

[3.3.2.9.] Outdoor places of assem-bly have separate requirements,since a large number of people inan open space constitutes a uniquesituation. Less stringent measuresapply to outdoor assembly struc-tures because smoke should beable to dissipate into the openspace in front of the seating area.

Also, access is usually available tothe open space behind the seatingarea by means of aisles and pas-sageways. Where barricades serve

to confine spectators or restrictaccess onto a playing field, specialconsideration should be given tothe egress design.

RESIDENTIAL OCCUPANCIES

In residential buildings, the mainconcern is that occupants may be asleep when a fire occurs, andconsiderable time may elapsebefore an emergency is realisedand evacuation begins. Eachdwelling unit must:

• be separated from adjacentdwelling units by fire separations [3.3.4.2.]

• provide egress that accommodatesvarious types of designs whilemaintaining an appropriate levelof safety [3.3.4.4.]

[3.3.4.2.] If a storage garage isattached to a dwelling unit andserves only that unit, no fire sepa-ration is required between theunit and the garage provided:

• the unit and the garage areseparated from the rest of thebuilding by at least a 45minute fire separation

• there are no duct systemsbetween the garage and theunit

• the wall between the unit andthe garage is an effective barrierto gas and exhaust fumes

• any door between the unit andthe garage is tight fitting,weather-stripped, fitted with aself closing device, and not in abedroom

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8.5 Safety within Floor Areas of Specific Occupancies

[3.3.4.2.(4)] The wall between agarage serving more than onedwelling unit and any dwellingunit can be a fire separation withno fire-resistance rating providedthe following conditions are met:• the garage contains no more

than five vehicles• the building is sprinklered• the conditions listed previously

for a garage serving a singleunit are met

CARE FACILITIES

The NBCC recognizes that inoccupancies such as hospitals andnursing homes, normal egress procedures from upper floors arenot applicable because occupantscannot evacuate the floor areawithout assistance from security,nursing or other personnel.

Therefore there must be provisionsto permit occupants to remaininside an institutional buildingfor an extended period of time during an emergency. This is theDefend Exposed in Place objectiveof the NFPA Fire Safety ConceptsTree.

[3.3.3.5.] To achieve this objective,more rigorous fire protection measures are required. In the 1995 NBCC, all buildings of careor detention occupancy must beequipped with automatic sprin-klers. In addition, during anemergency, it is often safer tomove bed patients occupying afloor area to a safer adjacent area.

To permit the horizontal move-ment of patients to relative safety,these floor areas must be dividedby fire separations into two or


FIGURE 8.8

Fixed seatingrestricts accessto exits

more fire compartments. Eachcompartment must not exceed1000m2. Such zones must be largeenough to hold their own occu-pants plus the occupants of thelargest adjacent zone.

REPAIR AND STORAGE GARAGES

Occupancies such as repair andstorage garages are subject toadditional restrictions because ofincreased hazards and sources ofignition. The concern with storage

garages relates mostly to thepotential carbon monoxide conta-mination of adjacent spaces. Theseadditional restrictions include:

• provision of mechanical ventilation [3.3.5.4]

• fire separation from other occupancies [3.3.5.5.]&[3.3.5.6.]

As noted, the fire resistance ratingof the fire separation betweenstorage garages and a dwellingunit can be waived in someinstances.

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[3.6.1.1.] Section 3.6 of the 1995NBCC regulates spaces which housebuilding service facilities such as:• ducts and pipes • electrical wires and cables • electrical transformers and

switchgear • heating furnaces, incinerators

and boilers • air-conditioning and mechanical

equipment • elevators, dumbwaiters and

escalators Such service spaces include atticand roof spaces, ceiling spaces, crawlspaces, elevator hoistways and shaftspaces, as well as specialized servicerooms. Service spaces are normallyunoccupied areas, but must be regu-lated because a fire may ignitewithin them, or they may be routesfor the spread of a fire.

[3.2.1.1.(7)] The NBCC providesfor access to some service spaces topermit maintenance and to aidfirefighting. These special spaces

or interstitial spaces are not con-sidered as a storey if they meet anumber of special requirements .

[3.6.2.] Apparatus such as fuel-fired equipment, incinerators ortransformers present a particularhazard because they have potentialto start fires. The NBCC thereforerequires that , under certain cir-cumstance, rooms containing thembe separated from the remainderof the building by fire separationswith a designated fire-resistancerating. Conversely, some servicerooms contain equipment belong-ing to the building’s emergencysystems, and must be protectedfrom a fire originating elsewhere.

[3.6.3.1.(1)] Vertical service spacessuch as shafts for building ser-vices, enclosures for linen orrefuse chutes, and dumbwaitersand elevators, must be separatedfrom each adjacent storey by fireseparations with a fire-resistancerating based on that of the floorassembly through which they pass.

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8.6 Service Spaces

FIGURE 8.9

Vertical servicespaces Suspended ceiling

FurnaceServicePiping

AirCond.

Suspended ceiling

45 minute shaft

45 minute floorand shaft

60 minute floorover service room

60 minute shaft

Shaft must provide 60 minute fire separation at bottom and 45 minute where it passes through the first and second storey and at the top; interior finish of shaft must have flame-spread rating of 25 or less.

This ensures that the degree ofprotection for that space is in keep-ing with the expected severity of afire on each floor area (Figure 8.9).

[3.1.13.2.] The interior wall sur-faces of service shafts are limitedto a flame-spread rating of 25.

[3.1.13.7.] In high buildings, thesmoked developed classification ofinterior finishes in vertical ser-vice spaces is also regulated andmust not exceed 50. This require-ment is intended to limit thepotential smoke hazard should afire occur in the space.

[3.6.3.3.] Refuse and linen chutesare notorious for nurturing firesbecause ashtrays with smoulderingcigarette butts are often dumpedinto them. For this reason, thechutes, as well as the rooms in to

which they discharge, must be sprin-klered, and additional fire safetyrequirements are also imposed.

Chapter 5 explains that when aceiling space is continuous above afire separation, it is treated as aseparate fire compartment. Theceiling must then be constructed asa fire separation with a designatedfire-resistance rating (Figure 8.10).

[3.6.5.4.] If the concealed space isused as a plenum for heating, venti-lating and air conditioning systems,the NBCC imposes restrictions onthe types of materials which may beused within that space to reduce thepossibility of the spread of fire andsmoke through these service areasto the rest of the building.

[3.2.1.1.(1)] Roof-top enclosures,such as elevator machinery rooms,due to their low occupant load, may

FIGURE 8.10

Horizontal service spaces


Subfloor

Joist

Ceiling

Duct

Ceiling support

12.5mm plywood fire stopping or sprinkler protection

30 minute fire-resistance rating required

45 minute fire separation

be omitted from the storey count in calculating building height.Therefore, a roof-top enclosure on afour-storey wood-building may alsobe of wood-frame construction.

[3.2.2.14.] Enclosed service roomson top of roofs must maintain the required fire separation of the floor assembly between theservice room and the storey below.The fire-resistance rating of theenclosure is waived if it is notmore than one storey high. Nofire separation is necessarybeneath unenclosed roof-topequipment.

Wood-frame enclosures for servicerooms containing heating and

cooling equipment are restricted to buildings permitted to be ofcombustible construction. Otherwood components besides the struc-tural members may be used in service rooms. Doors may be con-structed of wood or wood-basedmaterials.

Even where combustible construc-tion is permitted, the use of woodmay be limited by the degree ofhazard involved, as in incineratorrooms that require not less than atwo-hour fire separation. However,two layers of 15.9mm Type X (fire-resistant) gypsum wallboard onwood-stud framing can give therequired fire-resistance rating,thus providing the fire separation.

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Chapter SummaryThe primary objective of the NBCC is to ensure life safety. This can be achieved by a combination of measures designed to managethe fire and manage the people in accordance with the NFPA FireSafety Concepts Tree.

The Manage Exposed branch relies on three steps: • initiating the movement of the occupants by alerting them to the

emergency • providing means for occupants to move safely within the building

to an exit • ensuring that exits will lead to a safe destination

Certain occupancies are given special consideration due to hazardsrelated to the occupancy as well as to the ease of occupants to evacuatethe building. The provision of early warning and detection systems com-bined with facilities to aid firefighting (standpipes and sprinklers) areall part of the overall passive and active life safety systems provided ina building to ensure public safety.

The level of risk is reduced when a floor area or building is sprinkleredand consequently, the requirements are not as stringent in these cases.

9Provisions for Firefighting9.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

9.2 Access to Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

Access Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

Access Above Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308

Access Below Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308

9.3 Fire Protection Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

Water Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

Sprinkler Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311

Standpipes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316

Portable Fire Extinguishers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

Fires are usually controlled by

• applying cooling agents, usuallywater, to absorb heat and reducefuel temperatures

• by using an isolating agent, suchas foam, to separate the fuel fromoxygen and smother the fire

During a fire, heat may build uprapidly, and quickly heat addition-al fuels, such as building contents,to their ignition temperature. Asmall fire, once it reaches flamingconditions, can get out of controlwithin two or three minutes.

It is vital that a building bearranged so that any fire can bereached quickly. As well, manualor automatic fire suppression systems must be well designedand well maintained.

In the NFPA Fire Safety ConceptsTree, firefighting provisions andbuilding access fall under theManage Fire Impact branch,including both Manage Fire andManage Exposed. To meet theserequirements, access facilities must

be provided and maintained to per-mit fire department personnel to:

• reach the site• evaluate and suppress the fire

in the building• reach those exposed to the fire

Access may mean evacuation orprotection of the building occu-pants in place. More stringentrequirements apply to high build-ings (Chapter 10) because of theirhigher occupant load, and restrict-ed access and exiting which limitefforts to manage the exposed.

The spatial separation require-ments discussed in Chapter 7 aredesigned to reduce the likelihood offire spreading between buildings.The separation and constructionlimits are based on typical radia-tion levels experienced during afire, and the assumption that fire-fighting is available within 10 min-utes of the alarm being received.

Access routes for firefighters allowfirefighting apparatus to be placednear hydrants and near buildings.

Access routesfor firefightersprovide ameans for firefightingapparatus to be placed nearhydrants andnear buildingsfor evacuationpurposes.


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[3.2.2.10.] Every building isrequired to face at least one streetto provide firefighting access.Access routes provided on theproperty are permitted to be con-sidered as streets when determin-ing the minimum constructionand fire protection requirements(except when determining spatialseparation requirements).

[3.2.5.4.] Any building which ismore than three storeys in build-ing height or more than 600m2 inbuilding area must have at leastone access route on the property.For these larger buildings, theaccess routes must be adjacent tothe principal entrance and to anybuilding face required to face astreet.

[3.2.5.5.] For smaller buildingsrequired to face only one street,the access route can be anywherewithin 45m of any portion of thebuilding. This is because smallbuildings contain fewer people,are easily evacuated, and thus pre-sent a lesser risk to life.

Access is maintained for two typesof emergency response:• vehicles which must access

the building directly, such asambulances and ladder trucks

• pumper trucks, which boostwater supplies from the muni-cipal supply to the buildingeither via a hose stream orthrough a service connection

A building’s fire service connec-tions are commonly siamese con-nections which access a building’ssprinkler and/or a standpipe andhose system (Figure 9.1). The fireservice can ensure that pressurefor these systems is maintainedby pumping water from a remotesupply (usually the municipalsystem) through the siamese.

ACCESS ROUTES

[3.2.5.6.] The route which pro-vides emergency access to a build-ing must be connected to a publicthoroughfare so that fire depart-ment equipment can be drivenunimpeded to the scene of the fire.

Access to Buildings 305

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9.2 Access to Buildings

FIGURE 9.1

Typical exteriorstandpipe andsprinkler connections

Each access route must bedesigned to the following criteria(Figure 9.2):• be surfaced with concrete or

asphalt• be able to support the weight of

fire department equipment• minimum clear width of 6m• minimum overhead clearance

of 5m• minimum centreline radius

of 12m• no change in gradient

exceeding 1 in 2.5 over 15m• turnaround facilities in dead-

end portions exceeding 90m

[3.2.5.5.(1)] The location of theaccess route must allow accessdirectly to the building and alsoto the water supply system. Topermit direct access for ambu-lances and ladder trucks, theaccess route must be situated sothat it is:

• not less than 3m

• not more than 15m

from the principal entrance andaccess openings (Figure 9.2)

One of the first actions of aresponding fire department is toconnect to the hydrant closest tothe building. The location of the

FIGURE 9.2

Buildingaccess


Building(no fire department

connection)

3m min.15m max

if building > 3 storeysor > 600m2 building area

min radius = 12mLadder or emergency vehicle

Pumper truck

6m min.

Hydrant

Hose length ‘a’

Hose length ‘b’

a + b ≤ 90mb ≤ 45m

access route must also consideraccess to hydrants and to firedepartment connections on thebuilding.

[3.2.5.16] For buildings with fire department connections to astandpipe or automatic sprinklersystem:• the roadway or yard must be

adjacent to the hydrant • the connection must be not more

than 45m from the hydrant

[3.2.5.5.(2)] For buildings withoutfire department connections:• there must be a fire hydrant

within 90m of the building • paved access must not be more

than 45m from the building

These requirements allow apumper truck to get close enoughto easily boost a hose stream to thefire without excess friction loss inthe hoselines.

[3.2.5.5.(4)] Internal partitionscreate divisions which limit thearea accessible to the fire depart-ment through the principalentrance. There is a 45m limit ontravel distance from the accessroute to one entrance of eachdivided portion of buildings.

[3.2.2.] The tables of allowableheights and areas (Chapter 4) aredivided according to the amount offirefighting access provided forunsprinklered buildings. Anunsprinklered building facingthree streets is permitted to be greater in building area orbuilding height than one facingonly a single street.

[3.2.2.10.] To be considered as fac-ing two streets, 50% of the build-ing perimeter must be locatedwithin 15m of a street or accessroute. For facing three streets, atleast 75% of the building perime-ter must be within 15m of a streetor access route.

The improved accessibility pro-vides better means for evacuatingthe occupants and for attacking thefire from both inside and outsidethe building.

In the 1995 NBCC, the height and area of sprinklered buildingsdo not change according to theamount of access provided. Theheights and areas allowed by theprevious edition of the NBCC forfacing three streets are now per-mitted for sprinklered buildingsfacing only one street.

This change is based on the following:• Previous editions of the NBCC

did not require access openings(windows, doors) for firefight-ing purposes in any wall of abuilding or storey that wassprinklered. Since no openingswere required, the need forstreet access on two or threeblank wall faces of a sprin-klered building was questioned.

• Properly designed and main-tained sprinkler systems,which are electrically super-vised, have a high level of reliability.

• The sprinkler system is able toapply water directly to a fire,and the fire department canboost water pressures into thesprinkler system if necessary.


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ACCESS ABOVE GRADE

[3.2.5.1.] The importance ofattacking a fire from the interiorpositions is reflected in the NBCCby the requirements for directaccess into buildings. Firefightersmust have direct access to everyabove-grade storey that is notsprinklered and whose floor levelis less than 25m above grade.Access must be provided by atleast one unobstructed window oraccess panel for each 15m of wallface, measured horizontally.

These access panels must be locatedin a wall facing a street or accessroute so that firefighting equip-ment, such as hoses and ladders,may be brought up to the accesspanel and into the building.Although not specifically stated inthe NBCC, these access openingsshould be spaced regularly alongthe building face to provide opti-mum access to all areas.

[3.2.5.1.(3)] Access panels abovethe first storey should be:

• easy to open from both insideand outside of the building, or

• glazed with plain glass thatcan be readily broken

[3.2.5.1.(2)] A maximum windowsill height of 900 mm above theinside floor is specified to preventfire-fighters from injuring them-selves while entering the building.

Fire department access by win-dows, doors or access panels isalso required for the first storeyof a building because firefighterscannot always enter by the frontentrance or the exit facilities of abuilding.

Access openings are not requiredfor any storey, above or belowgrade, that is sprinklered. Thisreflects the ability of sprinklersto extinguish fires in their earlystages. Often, when firefightersarrive at a sprinklered building,the fire is either out or under control.

ACCESS BELOW GRADE

Storeys below grade are considereda serious fire hazard because :

• they are often cluttered withcombustible materials

• they are difficult to ventilate

• they are difficult to enter during a fire

[3.2.5.2.] Access to any unsprin-klered basement having a horizontal dimension more than 25m must be provided by:• doors, windows or other facili-

ties leading from the outdoorsfrom at least one street, or

• an interior stairway that isimmediately accessible fromthe outdoors


This allows firefighters to bring infire hose directly without goingthrough other parts of the building(which may already be inaccessibledue to the fire). If the basement issprinklered, access openings arenot required.

[3.2.2.15.] If the building extendsmore than one storey below groundlevel, all basement storeys must besprinklered (except for residentialoccupancies).

[3.2.2.15.(3)] In an unsprinkleredresidential building, the base-ment storey directly below thefirst storey is not required to be sprinklered if at least oneunobstructed access opening isinstalled on that storey for each15m of wall length in at least one wall required to face a street. This exception is allowedto accommodate the use of park-ing levels below residentialbuildings.


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WATER SUPPLY

Water supply required for fire-fighting purposes for any buildingdepends on:• building size• combustibility of building

contents• combustibility of the structure • level of hazard associated with

the occupancy• exposure hazard from neigh-

bouring buildings • whether or not the building

is sprinklered• whether or not a standpipe

system is provided

In crowded districts of largermunicipalities, the possibility of two or more fires creating asimultaneous heavy demand onthe public waterworks systemmust be considered.

[3.2.5.7.] A water supply systemshould be designed, installed and maintained to provide anadequate water supply for fire-fighting purposes. The publicwaterworks system often has tobe supplemented to provide anadequate quantity and pressureof water required to protect largebuildings. A secondary watersupply system is often provided consisting of:• fire pumps and reservoirs• pressure tanks or gravity tanks• private hydrants and fire

mains

[3.2.5.5.(2)] Although not explic-itly stated in the NBCC, ahydrant is required to be located

in close proximity to any buildingrequired to have access routes forfire department vehicles, as speci-fied in Article [3.2.5.4.]

A number of National FireProtection Association (NFPA)standards provide guidance onthe installation of private watersystems and methods for deter-mining minimum water supplyrequirements.

SPRINKLER SYSTEMS

For the 1995 NBCC, the provisionsrequiring sprinklers and the fireprotection requirements for build-ings with sprinklers were examinedin depth. This resulted in sprin-klers being required for many moretypes of buildings (Chapter 4). Theprovision of sprinklers however per-mits a relaxation of many Coderequirements such as:• an increase in the heights and

areas permitted• a reduction in the spatial sepa-

rations required• a reduction in the access required• a reduction in fire-resistance

ratings

The advantage of having sprin-klers ready at all times to immedi-ately discharge water on a fire isrecognized by these relaxations.The excellent record of sprinklersystems is affirmed in severalrecent reports. These emphasize theimportant role that these systemsplay in reducing fire losses in alltypes of construction.

Obviously, the presence of auto-matic fire sprinklers in a buildingalso plays a significant role in the

Fire Protection Systems 311

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9.3 Fire Protection Systems

fire department’s response in a firesituation. Usually, firefighters willconnect to the fire departmentpumper connection and boost thepressure in the sprinkler system toensure that an adequate supply ofwater reaches the fire (Figure 9.3).

In many cases, the fire is controlledby one or two sprinklers, and thefire department need only shut offthe system and assess the damage.

InstallationAutomatic sprinkler protection isa proven means of safeguardingproperty from fire, but like anyother fire protection system, itmust be installed and maintainedproperly to ensure proper functionwhen a fire occurs.

[3.2.5.13.] Automatic sprinklersystems, where required, must bedesigned, constructed, installedand tested in conformance with:

• NFPA 13, Standard for theInstallation of SprinklerSystems, or

• NFPA 13R, Standard for theInstallation of Sprinkler Systemsin Residential Occupancies up toand Including Four Stories inHeight, or

• NFPA 13D, Standard for theInstallation of SprinklerSystems in One- and Two-Family Dwellings and MobileHomes.


Siamese connection

Large water main on city system

Branch main

City hydrant

City Valve

Check Valve

Main control valve (indicator type)

Privatehydrant

Private hydrant

Tank controlvalves

Fire Pump

Water tankon tower

Pump suction tank

Sprinkler Alarm or check valve

Sprinkler shut off

Tank checkvalve

FIGURE 9.3

Typical sprinkler system

[3.2.5.13.(2)] NFPA 13R is permit-ted to be used for a building of resi-dential occupancy throughout, notmore than 4 storeys in buildingheight. NFPA 13D is permitted to beused for a building of residentialoccupancy throughout that containsnot more than 2 dwelling units.

[3.2.5.13.(7)] NFPA 13R andNFPA 13D are residential sprin-kler standards that have onlybeen recognized by the NBCCsince 1993. The NBCC requiresfast response residential sprin-klers which activate much morequickly than traditional commer-cial sprinklers. With these fast-acting sprinklers, the fire in theroom of fire origin is controlledmuch earlier, thereby reducingboth property and human losses.

Neither of the residential stan-dards require sprinklers to beinstalled in unused concealedspaces such as attics and floorspaces or in some small closetsand washrooms. Statistics show that fires originating in suchspaces do not significantly impactthe number of deaths or injuries.

The cost of sprinklering residentialproperties using these standards isreduced significantly (especially forwood-frame construction) because:

• many of the combustible concealed spaces do not have to be sprinklered

• the water supply for the sprinkler system installed toNFPA 13R is less than requiredunder NFPA 13

FIGURE 9.4

Sprinkler system controlsrequire periodic verification


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[3.2.5.13.(7)] Fast response sprin-klers must also be used for care ordetention occupancies. Since mostpeople in these occupancies haverestricted mobility, it is criticalthat the sprinklers activate as fastas possible to ensure tenabilitylevels in the room of fire originare maintained.

The provisions of NFPA 13 allow-ing fast-response sprinklers applyto most other occupancies coveredby the NBCC, including high-challenge warehouse occupancies.

Sprinkler systems are usuallyinstalled throughout a buildingand, in most cases, the NBCCrequires complete protection forthe building. In some cases, theNBCC requires only the floor areaor space to be sprinklered and not

the entire building (depending onthe hazard being protected andthe nature of the fire safety issue).

[3.3.2.5.(3)] For example, the fire-resistance rating of corridor wallsin certain occupancies is waived if the floor area is sprinklered.This is logical because the require-ments for fire-resistance ratingsproviding passive fire protectionare typically applied floor-to-floor,based on the occupancy hazard onthe floor.

[3.2.5.13.(6)] However, to avoidhaving a fire-resistance ratingrequired for a roof assembly, theentire building must be sprin-klered, due to the greater impactof a roof failure. Since the ratingof the roof assembly is waived, allrooms in the storey immediately

FIGURE 9.5

FirefightingEquipment (R to L):firefighters’telephone,standpipe andhose cabinetwith 38 and64mm con-nections,portable fireextinguisher,manual alarmand fire exit


below the roof assembly must be sprinklered, including thoserooms not otherwise required to be sprinklered by the applicablesprinkler standards.

As noted, the design standard,NFPA 13, typically requires sprin-klers to be installed throughout thebuilding, including any concealedspaces containing combustibles orexposed combustible surfaces.

There are, however, many instanceswhere sprinkler protection iswaived for these concealed spaceseven in buildings of wood-frameconstruction. Some of these com-bustible concealed spaces include:• spaces filled entirely with

noncombustible insulation• spaces formed by ceilings

attached directly to, or within152mm of wood joist construction

• spaces where the exposed sur-faces have a flame spread ratingof 25 or less and the materials donot propagate fire in the form inwhich they are installed in thespace, (for example, fire retar-dant treated wood)

Additional information on spacesthat are exempt from sprinklerprotection in wood frame construc-tion can be found in NFPA 13.

Although both NFPA 13 andNFPA 13R allow certain areas ofwood frame construction to beunsprinklered, the building isstill considered as sprinkleredthroughout. Consequently, anyoption in the NBCC afforded tosprinklered buildings apply, evenwith these unsprinklered portionsin the building.

Figure 9.3 shows a typical sprin-kler system and the outside watersupply services. The design andinstallation of these systems iscomplex, since the requirementsvary with construction type andoccupancy. Designers andinstallers must have extensive,specialized knowledge.

In general, sprinklers are installedon a fixed piping system through-out the building. They are typicallyinstalled as :

• wet pipe systems (water always in the piping) or

• dry pipe systems (air filledpipe with differential valveholding back the water)

[3.2.5.14.] Dry pipe systems areused mainly in areas subject tofreezing. The NBCC requirementsdo not usually specify the use ofone type of sprinkler system overthe other except that plastic pipingis restricted to wet pipe systems.

Sprinklers are fixed temperaturedetectors. They are equipped withfusible solder links or frangiblebulbs and will activate only whenthe design temperature is reached.The design temperature rangesfrom 38°C to 329°C depending onthe occupancy and the hazard.

Only the sprinklers located in theimmediate area of the fire willreach their design temperatureand activate. The number ofsprinklers operating will dependon the severity of the fire and theadequacy of the water supply.


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Water SupplyThe minimum water supplyrequired for the system depends on:• the building occupancy• the construction type• the design approach used to

size the system branch linesand feed mains

The hydraulic design approach calculates flow rates and pressurelosses in the system. It is commonlyused and usually results in muchlower water supply requirementsthan other design approaches, espe-cially for wood-frame buildings.

The NFPA’s Automatic SprinklerSystems Handbook and FireProtection Handbook provideextensive background and expla-nation on the design and use ofall types of automatic sprinklersystems. These documents are recommended to all sprinkler sys-tem designers who must interpretthe standards for fire protectionsystems installed to meet NBCCfire safety requirements.

STANDPIPES

Standpipe and hose systems arealmost always needed in unsprin-klered buildings, and in portions ofbuildings that cannot be accessedeasily with hose lines from outsidehydrants.

[3.2.5.8.] The NBCC requiresstandpipe and hose systems forany building:• more than three storeys in

building height

• more than 14m in heightbetween grade and the ceilingof the uppermost storey

• unsprinklered and less than14m in height and more thanthe building area listed inTable 3.2.5.8. of the NBCC.

Standpipe systems are designedfor two types of service:

• Small (38mm diameter) hoseattached to the standpipe out-let are intended for use byoccupants of a building to help control the fire until firefighters arrive.

• Larger (64mm diameter) con-nections are provided for the64mm diameter hose which isbrought into the building bythe firefighters.

These two types of service are usually provided by a singlestandpipe with separate valveoutlets provided to connect 38mmdiameter and 64mm diameterhose (Figure 9.5).

[3.2.5.10.(5)] Where a standpipeand hose system is provided in anunsprinklered building less than25m in height, the NBCC permitsthe exclusive use of 38mm diame-ter hose connections.

A 38mm diameter hose is adequatefor attacking the majority of firesthat can be fought with inside hoselines. Both building occupants andfirefighters can use 38mm hose butthe use of 64mm diameter hose islimited to firefighters.


[3.2.5.10.(1)] Standpipes should belocated in areas where the chanceof mechanical or fire damage isthe least. The large 64mm hoseconnections must be located closeto or in an exit so that they will bereadily available to firefighters.Some municipalities will not per-mit standpipe outlets to be locatedin stairways, while others insiston this location. Therefore thelocal authority should be con-sulted in the early design stages.

[3.2.5.11.(3)] Hose stations for38mm hoselines must be locatedin the floor area:• within 5m of exits• at other locations to provide

coverage to the entire floor area

[3.2.5.9.(1)] Where standpipe andhose systems are required by theNBCC, their design, construction,installation and testing must conform to NFPA 14, Installationof Standpipe and Hose Systems,unless the NBCC has other specificrequirements.

In sprinklered buildings wherestandpipe and hose systems arerequired, the sprinkler and stand-pipe systems typically use a com-bined riser to supply water toeach floor. NFPA 13 providesguidance for the valve arrange-ments and minimum water supply requirements.

PORTABLE FIRE EXTINGUISHERS

[3.2.5.17.(1)] Portable fire extin-guishers should be located andmaintained throughout the build-ing, according to the requirementsof:

• the appropriate provincial, territorial, or municipal regulations or,

• the National Fire Code ofCanada 1995 (in the absence of local regulations)


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Chapter SummaryThis chapter reviewed the NBCC requirements which facili-tate firefighting. These provisions apply to common buildingtypes. In industrial buildings, warehouses and unusualstructures, these provisions may not prove sufficient. TheNational Fire Protection Association Handbook, providesadditional information.

10

High Buildings10.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

10.2 Fire Safety in High Buildings . . . . . . . . . . . . . . . . . . . . . . . . . 323

Smoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323

Appendix B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325

Flame-Spread Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325

Elevators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326

Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326

Central Alarm and Control Facility . . . . . . . . . . . . . . . . . . . . . . . 327

Voice Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

Protection of Electrical Conductors . . . . . . . . . . . . . . . . . . . . . . 327

Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

Emergency Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328

Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328

[3.2.6.1.] High buildings are classified by height and occupancytype. For most occupancy types,(Group A, D, E or F), high buildingsare classified as those buildingswhich are:

• more than 36m in height, measured between grade and the floor level of the topstorey, or

• more than 18m in height ifthere is an increased number of occupants per exit stair

Group C, residential buildingsand Group B, care and detentionbuildings are classified as highbuildings if:

• the Group C or Group B occupancy is located more than 18m above grade, or

• floor areas above the thirdstorey are intended for hospitaland nursing home use (GroupB, Division 2)

[3.1.5.] All high buildings (regulated by NBCC Subsection3.2.6.) are required to be of noncom-bustible construction. However, a considerable amount of wood(Chapter 2) is permitted to be usedin partitions, exterior walls, fin-ished flooring and stage flooring,interior finish, trim and millwork.With certain minimum restric-tions, wood-frame partitions maybe used throughout all buildingsof noncombustible construction,including high buildings.

High-rise buildings present specialfire safety hazards


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In high buildings, immediate evac-uation of all floors is impossiblebecause of:• the large occupant load • considerable vertical travel

distances

A main objective of the NBCCis to provide safety to occupantsfor a sufficient period of time tocomplete evacuation.

This objective is achieved in high buildings by incorporating additional fire safety measures in the design, such as:• smoke control systems

• increased fire resistance ofmajor structural components

(Design Requirement Tables,Chapter 4)

• automatic sprinkler protection

SMOKE

Smoke is usually the major hazardto occupants of high buildings(Figure 10.1). As explained inChapter 1, the vertical movementof smoke is caused by pressure dif-ferentials in the building result-ing from temperature differencesat the exterior boundaries of thebuilding.

FIGURE 10.1

Smoke hazardspresentincreased risk in highbuildings

Fire Safety in High Buildings 323

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10.2 Fire Safety in High Buildings

The heating of a building in coldweather draws air into the build-ing at low levels and discharges itout at upper levels, creating a stackeffect. This direction of flow isreversed in the summer when warmair is drawn down by the cooler air-conditioned air. (Figure 10.2)

In a fire situation, the heat generated by the fire results inthermal expansion of the gases.Smoke and hot gas are forced outof compartments by the air cur-rents created by a fire that hasreached flashover. Stack effect inhigh buildings magnifies thiseffect, increasing the hazard evenmore. Air handling systems andvertical shafts in the buildingsalso contribute to vertical smokemovement.

[3.2.6.2.] In the 1995 NBCC, allbuildings over six storeys arerequired to be sprinklered. Eventhough sprinklers will hold afire in check in the early stages,floor areas will still tend to fillwith smoke. To ensure that evac-uation is possible, stairs must beseparated and pressurized duringa fire emergency. Pressurizationof stair shafts keeps smoke andhot gases out of the stairways.

Vented or pressurized vestibulesare used to counteract pressuredifferentials between floor areasand shafts, helping to controlsmoke movement. Similarly, pressurization can prevent smokefrom entering shafts containingelevators for firefighters.


WinterWarm Building / Cold Air

updraft

vent

SummerCool Building / Hot Air

downdraft

vent

relativepressure

– + relativepressure

+ –

relativepressure

+ – relativepressure

– +

FIGURE 10.2

Stack effect

APPENDIX B

Appendix B of the NBCC entitled,Fire Safety in High Buildings, givesdirection for the design of fire safeconstruction for high buildings.

The measures described inAppendix B are intended to con-trol smoke movement caused bystack effect and other phenomena.The measures vary for buildingheight, occupancy type and size,and illustrate acceptable ways ofachieving the same level of safetyfor buildings of different design.

They are not intended to excludeany other equally effective measurefor controlling smoke movement inhigh buildings. However, the incor-poration by a designer of one of themeasures is considered to be anacceptable means of complyingwith the NBCC.

Various conditions and combina-tions of protection are consideredin Appendix B, such as: • automatic sprinklers• vented corridors and vestibules • pressurized stair shafts• pressurized buildings• vertically divided buildings

A designer should consultAppendix B to understand theintent of the requirements ofSection 3.2.6. and how to meet them.

FLAME SPREAD RATING

[3.1.13.7.] For high buildings,stricter limits than those requiredfor low-rise buildings are imposed

on the flame-spread rating (FSR)and the smoke developed classifi-cation (SDC) of interior finishmaterials.

High-rise buildings are the onlybuildings where FSR and SDC offloor coverings are regulated witha maximum flame-spread rating of:

• 25 for floors in exits and service spaces

• 300 for floors in corridors, elevator cars and vestibules

There are no limits imposed onflame-spread rating on floor coverings in other areas of thebuilding.

[TABLE[D-3.1.1.B] Hardwood andsoftwood flooring (either unfin-ished or finished with a spar orurethane varnish coating) isassigned flame-spread and smokedeveloped classifications of 300(Appendix D). This permits thesefloorings to be used throughouthigh buildings except in specificexit areas and service rooms.

[3.1.13.7.(2)] Provided the highbuilding is sprinklered throughout:

• the smoke developed classifica-tion requirements for wall, floorand ceiling finishes are waived,except in care and detentionbuildings and elevator cars

• the less restrictive flame-spreadrating requirements for interiorfinish in other buildings, asdetailed in Article 3.1.13.2., apply

In most instances wood trim, millwork and doors are permitted.


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ELEVATORS

[3.2.6.4.] Elevators are controlledby key-operated switches, locatedconspicuously at:• each elevator lobby at the

recall level• the central alarm control facility• each elevator car

These switches enable the cars,including elevator cars on inde-pendent key-operated service, to bebrought down to the recall level.Once in the control of firefighters,the switches allow operation of theelevator car independently of floorcall buttons.

[3.2.6.5.] At least one elevator for firefighters is required. Thiselevator must:

• be constructed in accordancewith specifications of Article3.2.6.5.

• be available at the storey havingthe entrance intended for fire-fighter access

• have an elevator shaft designedto be kept free of smoke

• have a power supply which isprotected from fire to ensure its availability to access upperfloors

VENTING

[3.2.6.6.] Means of venting eachfloor area must be provided by:

• smoke shafts

• windows or wall panels, or

• the building exhaust system


FIGURE 10.3

Firefighters’control panel

Venting is necessary to exhaustunburned combustion gases andprevent explosions. Appendix B of the NBCC describes varioussolutions for venting dependingon which features are selected.

Windows used for venting must be suitably identified and capableof being opened. It is not acceptableto provide venting by breaking window glass because this wouldendanger people in the street below.

CENTRAL ALARM AND CONTROL FACILITY

[3.2.6.7.] A central alarm and con-trol facility must be provided onthe storey containing the entrancefor firefighter access to allow fire-fighting to be co-ordinated from acentral facility (Figure 10.3). Thisfacility must have means to controlthe voice communication andalarm systems in the building.

This facility must be located so thatit is readily accessible to firefightersentering the building. Its locationshould also take into account back-ground noise that occurs in fireemergencies which could hinderoperations .

VOICE COMMUNICATION

[3.2.6.8.] For buildings more than36m high, or buildings designedor intended for hospital or nurs-ing home use above the thirdstorey, a voice communication system is necessary to:

• direct occupants to safety

• maintain effective communica-tion between floor areas andthe central control facility

Two-way radio sets used for com-munication by firefighters tendto be screened by the massivestructural frame of a high build-ing and are not effective.

[3.2.4.22.] The voice communica-tion system must consist of:

• a two way communication system between each floor area and the control centre

• loudspeakers operated from thecentral control facility that areaudible clearly in all parts ofthe building

PROTECTION OF ELECTRICAL CONDUCTORS

[3.2.6.9.] Electrical conductorsmust be designed or installed sothat they are protected from fireexposure, for not less than onehour. This ensures operation ofessential services during a fireemergency.

Electrical conductors serving theemergency power supply mustremain protected from fire expo-sure for two hours. Copper-jacketedmineral-insulated cable has beenshown by test to carry its full elec-trical load under CAN/ULC-S101fire exposure conditions for thislength of time.

TESTING

[3.2.6.10.] Because of the signifi-cant hazard of smoke in highbuildings, testing of the systemsfor control of smoke movementand mechanical venting systemsis required.


10

Hig

h B

uilid

ng

s

EMERGENCY POWER SUPPLY

[3.2.7.8.] An emergency powersupply must be provided as analternative to the normal electri-cal power supply for fire alarm andvoice communication systems. Theemergency power must be capableof operating under full load fortwo hours for high buildings.

[3.2.7.9.] Emergency power supplycapable of operating under fullload for not less than two hours isrequired for:

• pumps supplying water for fire-fighting or automatic sprinklersystems

• venting fans

• smoke control fans

• elevators in buildings morethan 36m high

• every firefighter elevator

The emergency power supply mustbe capable of serving all elevatorsbut need only have capacity tosupply firefighters’ elevators plusone additional elevator at a time.


Chapter SummaryHigh buildings have special requirements because evacuation iscomplicated by occupant load and travel distances. The NBCCgives direction for measures to provide sufficient evacuation timesuch as:

• smoke control systems

• increased fire resistance of structural components

• automatic sprinkler systems

Other requirements specific to high buildings are also described.

AppendixInformation Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331

Index of Tables and Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345

Index of Code References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

CANADA

Alberta Forest Products Association (AFPA)

11710 Kingsway Avenue, Suite 200Edmonton, AB T5G 0X5Telephone: (403) 452-2841Fax: (403) 455-0505

Wood Products Consumer Information

L’Association des manufacturiers de bois desciage du Québec (L’AMBSQ)(Québec Lumber Manufacturers Association)

5055, boul. Hamel ouest, bureau 200Québec QC G2E 2G6Telephone: (418) 872-5610Fax: (418) 872-3062

Lumber

Canadian Codes Centre

c/o National Research Council of CanadaMontreal RoadOttawa, ON K1A 0R6Telephone (613) 993-9960Fax: (613) 952-4040

Building Codes Development,Technical Support

Canadian Commission on Building and Fire Codes (CCBFC)

c/o National Research Council of CanadaMontreal RoadOttawa, ON K1A 0R6Telephone: (613) 993-5797Fax:(613) 952-4040

Building Code Development

Canadian Construction Materials Centre(CCMC)

c/o National Research Council of CanadaMontreal RoadOttawa, ON K1A 0R6Telephone: (613) 993-6189Fax: (613) 952-0268

Building Products Assessment

Canadian Hardwood Plywood Association(CHPA)

27 Goulburn AvenueOttawa, ON K1N 8C7Telephone: (613) 233-6205Fax: (613) 233-1929

Hardwood Plywood

Canadian Home Builders Association (CHBA)

200, 150 Laurier Avenue W.Ottawa, ON K1P 5J4Telephone: (613) 230-3060Fax: (613) 232-8214

Residential Building

Canadian Institute of Treated Wood (CITW)(Institut canadien des bois traités)

200, 2430 Don Reid DriveOttawa, ON K1H 8P5Telephone: (613) 737-4337Fax: (613) 247-0540

Treated Wood Consumer Information

Canadian Lumber Standards AccreditationBoard (CLS)

103, 4400 Dominion StreetBurnaby, BC V5G 4G3Telephone: (604) 451-7313Fax: (604) 451-7343

Lumber Grading, Standards

Information Sources 331

Information Sources

APPENDIX

There are many specialist groups in Canada and the United Stateswhich offer technical information on building codes and fire safetyand assistance on the use of wood and wood products in buildingconstruction.

If you have a technical inquiry and are not sure who to call, contactthe Canadian Wood Council in Canada or the American Wood Councilin the United States for guidance.

Canadian Lumbermen’s Association (CLA)(Association canadienne de l’industrie du bois)


Wood Products

Canadian Particleboard Association (CPA)


Particleboard

Canadian Plywood Association (CanPly)

735 West 15th StreetNorth Vancouver, BC V7M 1T2Telephone: (604) 981-4190Fax: (604) 985-0342

Plywood

Canadian Standards Association (CSA)

178 Rexdale BoulevardEtobicoke, ON M9W 1R3Telephone: (416) 747-4000Fax: (416) 747-2475

Material and Design Standards

Canadian Wood Council (CWC)

350, 1730 St. Laurent Blvd.Ottawa, ON K1G 5L1Telephone: (613) 247-7077Fax: (613) 247-7856

Wood Products: Consumer InformationCodes and StandardsWood Engineering

Canadian Wood Preserver’s Bureau (CWPB)

c/o Canadian Institute of Treated Wood200, 2430 Don Reid DriveOttawa, ON K1H 8P5Telephone: (613) 737-4337Fax: (613) 247-0540

Treated Wood Certification and Inspection

Canadian Wood Truss Association

350, 1730 St. Laurent Blvd.Ottawa, ON K1G 5L1Telephone: (613) 247-7077Fax: (613) 247-7856

Wood Trusses

Cariboo Lumber Manufacturers Association(CLMA)

205, 197 Second Avenue NorthWilliams Lake, BC V2G 1Z5Telephone: (604) 392-7778Fax: (604) 392-4692

Lumber

Central Forest Products Association, Inc.(CFPA)

P.O. Box 1169Hudson Bay, SK S0E 0Y0Telephone: (306) 865-2595Fax: (306) 865-3302

Lumber

Council of Forest Industries of British Columbia (COFI)

1200, 555 Burrard StreetVancouver, BC V7X 1S7Telephone: (604) 684-0211Fax: (604) 687-4930

Lumber, Consumer Information

Forintek Canada Corp. (FCC)

Head Office, Western Laboratory2665 East Mall, UBCVancouver, BC V6T 1W5Telephone: (604) 222-5702Fax: (604) 222-5703

Forest Products Research Laboratory


Eastern Laboratory319 rue FranquetSainte Foy, QC G1P 4R4Telephone: (418) 659-2647Fax: (418) 659-2922



Information Sources continued

APPENDIX


Fire Research CenterCarleton Technology Training Centre4100, 1125 Colonel By DriveOttawa. ON K1S 5R1Telephone: (613) 523-0288Fax: (613) 523-0502

Fire Research, Fire Performance of Wood Products

Gypsum Manufacturers Association of Canada

1052 Johnathan DriveMississauga, ON L4Y 1K1Telephone: (905) 897-2624Fax: (905) 897-2624

Gypsum Building ProductsConsumer Information

Inchcape Testing Services – Warnock Hersey

3210 American DriveMississauga, ON L4V 1B3Telephone: (905) 678-7820Fax: (905) 678-7131

Fire Testing

Interior Lumber Manufacturers Association(ILMA)

360, 1855 Kirschner RoadKelowna, BC V1Y 4N7Telephone: (604) 860-9663Fax: (604) 860-0009

Lumber

Maritime Lumber Bureau (MLB)(Bureau du bois de sciage des Maritimes)

P.O. Box 459Amherst, NS B4H 4A1Telephone: (902) 667-3889Fax: (902) 667-0401

Lumber

National Fire Laboratory (NFL)

c/o National Research Council of CanadaMontreal RoadOttawa, ON K1A 0R6Telephone: (613) 993-2204Fax: (613) 954-0483

Fire Research, Fire Modelling

National Lumber Grades Authority (NLGA)

103, 4400 Dominion StreetBurnaby, BC V5G 4G3Telephone: (604) 451-7323Fax: (604) 451-7388

Lumber Grading

Northern Forest Products Association (NFPA)

400-1488 Fourth AvenuePrince George, BC V2L 4Y2Telephone: (604) 564-5136Fax: (604) 564-3588

Lumber

Ontario Lumber Manufacturers Association(OLMA)(Association des manufacturiers de boisde sciage de l’Ontario)

1105, 55 University AvenueP.O. Box 8Toronto, ON M5J 2H7Telephone: (416) 367-9717Fax: (416) 367-3415

Lumber

Structural Board Association (SBA)(Association de panneau structural)

412, 45 Sheppard Avenue EastWillowdale, ON M2N 5W9Telephone: (416) 730-9090Fax: (416) 730-9013

OSB, Waferboard

Truss Plate Institute of Canada (TPIC)

c/o GangNail Canada Inc.P.O. Box 1329Bradford, ON L3Z 2B7Telephone: (905) 775-5337Fax: (905) 775-9698

Truss Plates, Trusses



APPENDIX

Underwriters’ Laboratories of Canada (ULC)

7 Crouse RoadScarborough, ON M1R 3A9Telephone: (416) 757-3611Fax: (416) 757-9540

Fire Test StandardsFire Protection EquipmentProduct standards and certification,Fire Testing

Western Wood Truss Association (WWTA)

8428, 213 StreetLangley, BC V1M 2J1Telephone: (604) 888-7905Fax: (604) 888-7905

Wood Trusses

UNITED STATES

American Hardboard Association

1210 West NW HighwayPalatine, IL 60067Telephone: (708) 934-8800Fax: (708) 934-8803

Hardboard

American Institute of Timber Construction(AITC)

140, 7012 S Revere ParkwayEnglewood, CO 80112Telephone: (303) 792-9559Fax: (303) 792-0669

Glulam

American Society for Testing and Materials (ASTM)

100 Barr Harbor DriveWest Conshohocken, PA 19428-2959Telephone: (610) 832-9500Fax: (610) 832-9555

Material Standards, Fire Test Standards

American Wood Council (AWC)

800, 1111 – 19th Street NWWashington, DC 20036Telephone: (202) 463-2769Fax: (202) 463-2791

Wood Products: Consumer InformationWood Engineering, Codes and Standards

APA The Engineered Wood Association

7011 South 19th StreetTacoma, WA 98411Telephone: (206) 565-6600Fax: (206) 565-7265

Plywood, OSB, Waferboard, Structural-Panels, Glulam

Building Officials and Code AdministratorsInternational, Inc. (BOCA)

4051 West Flossmoor RoadCountry Club Hills, IL 60478Telephone: (708) 799-2300Fax: (708) 799-4981


California Redwood Association

200, 405 Enfrente Dr.Novato, CA 94949Telephone: (415) 382-0662Fax: (415) 382-8531

Redwood Lumber Products

Cedar Shake & Shingle Bureau

275, 515-116th Street NEBellevue, WA 98004Telephone: (206) 453-1323Fax: (206) 455-1314

Shingles & Shakes

Council of American Building Officials(CABO)

5203 Leesburg Pike, Suite 708Falls Church, VA 22041Telephone: (703) 931-4533Fax: (703) 379-1546

Represents Building Officials

Factory Mutual Research Corporation

1151 Boston Providence TurnpikeNorwood, MA 02062Telephone: (617) 762-4300Fax: (617) 762-9375

Fire Protection Systems,Fire Testing

334 Fire and Safety Design in Buildings


APPENDIX

Forest Products Laboratory (FPL)

One Gifford Pinchot DriveMadison, WI 53705-2398Telephone: (608) 231-9200Fax: (608) 231-9592


Gypsum Association

510, 810 First Street, N.E.Washington, DC 20002Telephone (202) 289-5440Fax (202) 289-3707

Gypsum Building Products,Consumer Information

Hardwood Plywood & Veneer Association(HPVA)

P.O. Box 2789Reston, VA 22090Telephone: (703) 435-2900Fax: (703) 435-2537

Hardwood Plywood and Veneers

International Conference of Building Officials(ICBO)

5360 Workman Mill RoadWhittier, CA 90601Telephone: (310) 699-0541Fax: (310) 908-5524


National Association of Home Builders (NAHB)

15th & M St. NWWashington, DC 20005Telephone: (202) 822-0200Fax: (202) 822-0374

Residential Building

National Fire Protection Association(NFirePA)

1 Batterymarch ParkQuincy, MA 02269Telephone: (617) 770-3000Fax: (617) 770-0200

Fire Standards,Sprinkler Standards, Fire safetyCodes and Standards

National Institute of Building Sciences (NIBS)

400, 1201 L Street NWWashington, DC 20005Telephone: (202) 289-7800Fax: (202) 289-1092

Building Regulations and Technology

National Institute of Standards andTechnology (NIST)

Building and Fire Research LaboratoryGaithersburg, MD 20899Telephone: (301) 975-5900Fax: (301) 975-4032

Fire Research, Fire Modelling

National Particleboard Association

18928 Premiere CourtGaithersburg, MD 20879Telephone: (301) 670-0604Fax: (301) 840-1252

Particleboard

Society of Fire Protection Engineers (SFPE)

One Liberty SquareBoston, MA 02109Telephone: (617) 482-0686Fax: (617) 482-8184

Fire Protection Engineering,Fire Research, Fire Modeling

Southern Building Code CongressInternational (SBCCI)

900 Montclair RoadBirmingham, AL 35213Telephone: (205) 591-1853Fax: (205) 592-7001


Underwriters’ Laboratories Inc. (UL)

333 Pfingsten RoadNorthbrook, IL 60062Telephone: (708) 272-8800Fax: (708) 272-8129

Fire Test Standards, Fire Testing



APPENDIX


APPENDIX

TABLES

Table 1.1 17NBCC Standing Committee on Fire Protection

Table 2.1 33Minimum dimensions of wood elements in heavy timber construction

Table 2.2 40Permitted uses of heavy timber construction in or as an alternative to noncombustible construction

Table 4.1 74Classification of buildings

Table 4.2 84Fire separation required between major occupancies

Table 4.3 91Mandatory sprinklers in the 1995 NBCC

Table 5.1 140Restrictions on temperature rise and glazing for closures

Table 5.2 159Time assigned to wallboard membranes

Table 5.3 160Time assigned for contribution of wood or light steel frame

Table 5.4 162Flooring or roofing over wood, cold formed steel members or open-web steel joists

Table 5.5 162Fire-resistance rating for ceiling membranes

Table 5.6 176Fire severity based on fire load concept

Table 6.1 205Assigned flame-spread ratings and smoke developed classifications

Table 6.2 206Typical flame-spread ratings and smoke developed classifications of wood products

Table 6.3 211NBCC requirements for interior finish and exterior glazing

Table 6.4 212Additional interior finish requirements for high buildings regulated by Subsection 3.2.6.

Table 7.1 239Construction of exterior walls

Table 8.1 284Egress in floor area not sprinklered throughout

Table 8.2 284Egress in floor area sprinklered throughout

FIGURES

Chapter 1 Lead Photograph 2Canadian building regulations provide for extensive wood structures

Figure 1.1 3The Boston Fire in 1872 was one of several major city fires that identified the need for new fire regulations

Figure 1.2 5National Building Code of Canada, 1941, 1953, 1995

Figure 1.3 9Fire claimed 492 lives at Boston’s Cocoanut Grove in the fall of 1942. It had a significant impact on regulations for exits and interior finishes.

Figure 1.4 11A fire on the ground floor of Chicago’s 22-storey LaSalle Hotel, considered to be a “fire-resistive” building, sent hot gasesthrough the ventilation system to the upperfloors, forcing evacuation.

Figure 1.5 12A welder’s torch ignited combustible insulation material in the basement of the highrise CIL House, Montreal in 1962

Figure 1.6 15Recent fires continue to emphasize the fire hazards of high-rise structures

Chapter 2 Lead Photograph 28Many varieties of wood components create structural forms

Figure 2.1 30Steel loses strength at elevated temperatures

Index of Tables and Figures 337

Index of Tables and Figures

APPENDIX

Figure 2.2 31Wood-frame construction

Figure 2.3 32Heavy timber construction

Figure 2.4 34Heavy timber connections

Figure 2.5 35Connection details

Figure 2.6 36Detail I Built-up truss joint

Figure 2.7 36Floor decks

Figure 2.8 42Wood frame exterior wall in noncombustible construction

Figure 2.9 43Wood stud framing in exterior wall of noncombustible building

Figure 2.10 44Raised wood floor

Chapter 3 Lead Photograph 50Business and medium hazard industrial complex in wood

Figure 3.1 53NFPA Fire Safety Concepts Tree

Figure 3.2 57Post-fire interior

Figure 3.3 61Fire safety requirements must be addressed early in the design stages

Figure 3.4 63Firefighter and the aftermath

Chapter 4 Lead Photograph 70Thompson Community Centre, Richmond B.C

Figure 4.1 73Heavy timber skeleton of an arena

Figure 4.2 75Determining building area

Figure 4.3 76Determining grade

Figure 4.4 77Determining number of storeys

Figure 4.5 78Artificially raised grade

Figure 4.6 78Mezzanines and building heights

Figure 4.7 79Multiple levels of mezzanine

Figure 4.8 80Office is a subsidiary occupancy to the warehouse

Figure 4.9 82Multiple occupancy

Figure 4.10 86Fire-resistance rating of supporting assemblies

Figure 4.11 92Four-storey wood-frame construction

Figure 4.12 93Impact of sprinkler changes

Chapter 5 Lead Photograph 130Wall assembly being removed from the furnace after a fire-resistance test

Figure 5.1 133Large multi-unit buildings are divided by rated fire separations to create fire compartments

Figure 5.2A 136Continuity of vertical fire separations

Figure 5.2B 136Continuity of vertical fire separations

Figure 5.3 137Vertical shafts

Figure 5.4 143Wood joists in noncombustible fire separations

Figure 5.5 143Fire wall connection details

Figure 5.6 144Erection of trusses onto a firewall

Figure 5.7 145Firewall support

Figure 5.8 148Fire test furnace for floors and roofs

Figure 5.9 148Fire test furnace for walls


Index of Tables and Figures continued

APPENDIX

Figure 5.10 150Fire test furnace for columns

Figure 5.11 154Listed wood joist floor assembly

Figure 5.12 155Listed wood stud wall assembly

Figure 5.13 169Load factor for glulam fire-resistance calculations (NBCC, 1995)

Figure 5.14 170Glulam exposure cases (NBCC Appendix D, 1995)

Figure 5.15 174Harmathy’s ten rules of fire endurance

Figure 5.16 175Ingberg’s hypothesis on equal fire severities

Figure 5.17 179Fire separations in residential occupancies

Figure 5.18 180Continuity of separations

Figure 5.19 181Mixed construction: wood trusses on heavy timbers on steel columns

Figure 5.20 183Exceptions for exterior unprotected members

Figure 5.21 186Typical atriums and exits

Figure 5.22 190Wood-frame fire stopping

Figure 5.23 191Wood-frame fire stopping

Figure 5.24 191Furring as fire stopping

Figure 5.25 191Stair fire stopping

Figure 5.26 192Plywood as attic fire stopping

Figure 5.27 193Sprinklers allow for use of heavytimber roof assemblies in largenoncombustible buildings

Chapter 6 Lead Photograph 198In Group A, Division 2 occupancies wall and ceiling finishes with a Flame-SpreadRating of up to 150 are permitted

Figure 6.1 201The Steiner tunnel for measuring surface burning characteristics

Figure 6.2 213FRTW label

Figure 6.3 215Loading wood into fire-retardant treatment pressure cylinder

Figure 6.4 217FRTW roof assembly alternative

Figure 6.5 218Fire-retardant treated wood roof systems

Figure 6.6 220Test apparatus for roof covering materials

Figure 6.7 221Wood shingle roof

Chapter 7 Lead Photograph 226The proximity of buildings is controlled to reduce potential for conflagrations

Figure 7.1 229Spatial separation determines both wall construction and amount of openings

Figure 7.2 233Limiting Distance

Figure 7.3 236Limiting distance and recessed opening

Figure 7.4 237Compartmentation and exposing building face

Figure 7.5 239Walls as unprotected openings

Figure 7.6 241Limiting distance for exterior structural members

Figure 7.7 243Unlimited unprotected openings at street level

Index of Tables and Figures 339


APPENDIX

Figure 7.8 246Separation of openings in exterior walls

Figure 7.9 247Protection of soffits

Figure 7.10 248Separation of window openings and skylights

Figure 7.11 253Limiting Distances - Examples 7.1 and 7.2

Figure 7.12 257Limiting Distances - Examples 7.3 and 7.4

Figure 7.13 259Limiting Distances - Example 7.3 Option W7.3B

Figure 7.14 261Limiting Distances - Example 7.3 Option W7.3C and N7.3C

Chapter 8 Lead Photograph 266The NBCC specifies exit requirements

Figure 8.1 270Number and characteristics of occupants determine design standards

Figure 8.2 278Smoke detectors

Figure 8.3 282Typical access for floor areas

Figure 8.4 283Corridors and classroom doorways provide access to exit

Figure 8.5 285Undivided floor area

Figure 8.6 286Public corridor divided from floor area by rated fire separations

Figure 8.7 291Public corridor not divided from floor area by rated fire separations

Figure 8.8 294Fixed seating restricts access to exits

Figure 8.9 297Vertical service spaces

Figure 8.10 298Horizontal service spaces

Chapter 9 Lead Photograph 302Access routes for firefighters provide a means for firefighting apparatus to be placed near hydrants and near buildings for evacuation purposes

Figure 9.1 305Typical exterior standpipe and sprinkler connections

Figure 9.2 306Building access

Figure 9.3 312Typical sprinkler system

Figure 9.4 313Sprinkler system controls require periodic verification

Figure 9.5 314Firefighting equipment (R to L): firefighters’ telephone, standpipe and hose cabinet with 38 and 64mm connections, portable fire extinguisher, manual alarm and fire exit

Chapter 10 Lead Photograph 320High-rise buildings present special fire safety hazards

Figure 10.1 323Smoke hazards present increased risk in high buildings

Figure 10.2 324Stack effect

Figure 10.3 326Firefighters’ control panel



APPENDIX

1. Baird, Donal M., Montreal High-Rise Fire,NFPA Quarterly, Vol. LVII, National FireProtection Association, Boston, MA, 1963.

2. Baird, Donal M., The Story of Firefightingin Canada, Boston Mills Press, Erin,Ontario, 1986.

3. Building the Future — The Strategic Plan ofthe Canadian Commission on Building andFire Codes 1995 – 2000, National ResearchCouncil of Canada, Ottawa, 1996.

4. Browne, F.L., Rep. No. 2135, USDA ForestServices, Forest Product Lab., Madison,WI, 1958.

5. Castino, G.T. and Harmathy, T.Z., eds.,Fire Risk Assessment, American Societyfor Testing and Materials, Special TechnicalPublication 762, Philadelphia, PA, 1980.

6. CCBFC Policies and Procedures 1992,National Research Council of Canada,Ottawa NRCC No. 34136, 1992.

7. Cote A.E. and Linville, J.L., eds., FireProtection Handbook, 17th Edition, NationalFire Protection Association, Quincy, MA, 1991.

8. Cote, Ron., ed., Life Safety CodeHandbook, Sixth Edition, National FireProtection Association, Quincy, MA, 1994.

9. Criteria for Use in Extension of Data fromFire Endurance Tests, ULC SubjectC263(e)-M1988, Underwriters’ Laboratoriesof Canada, Toronto, Ontario, 1988.

10. di Nenno, P.J., et al, eds., SFPE Handbookof Fire Protection Engineering, 2nd Edition,National Fire Protection Association,Quincy, MA, 1994.

11. Drysdale, D., An Introduction to FireDynamics, John Wiley and Sons Ltd., 1985.

12. Engineering Design in Wood (Limit StatesDesign) CAN/CSA-O86.1-M94, CanadianStandards Association, Toronto, Ontario, 1989.

13. Ferguson, R.S., Principles of Fire ProtectionApplied in Part 3: Use and Occupancy,National Building Code of Canada, TechnicalPaper No. 272, Division of BuildingResearch, National Research Council ofCanada, Ottawa, NRCC 10054, 1970.

14. Certification Listings, Inchcape TestingServices – Warnock Hersey Listing Services,Mississauga, Ontario, 1995.

15. Fire Resistance Design Manual, GA-600-92,Gypsum Association, Thirteenth Edition,Washington, DC, 1992.

16. Fire Resistance Directory, Underwriters’Laboratories Inc., Volumes I and II,Northbrook, IL, 1994.

17. FM Approval Guide, Factory MutualCorporation, Norwood, MA, 1996.

18. Fowell, Andrew J., ed., Fire and Flammabilityof Furnishings and Contents of Buildings,American Society for Testing and Materials,Special Technical Publication 1233,Philadelphia, PA, 1994.

19. Galbreath, M., Fire Endurance of LightFramed and Miscellaneous Assemblies,Technical Paper No. 222, Division of BuildingResearch, National Research Council ofCanada, Ottawa, NRCC 9085, 1966.

20. Galbreath, M., Fire in High Buildings,Division of Building Research, Fire StudyNo. 21, National Research Council ofCanada, Ottawa, NRCC 10081, 1968.

21. Gosselin, G.C., Fire Compartmentation andFire Resistance, Proceedings of BuildingScience Insight ‘87, Institute for Research inConstruction, National Research Council ofCanada, Ottawa, NRCC 28277, 1987.

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APPENDIX

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41. Mehaffey, J.R., ed., Mathematical Modelingof Fires, American Society for Testing andMaterials, Special Technical Publication983, Philadelphia, PA, 1988.

42. National Fire Code of Canada, CanadianCommission on Building and Fire Codes,National Research Council of Canada,Ottawa, NRCC No. 38727, 1995.

43. Objective Based Codes: A New ApproachFor Canada, National Research Council ofCanada, Ottawa, 1996.

44. Olesziewicz, Igor, The Concept and Practiceof Performance Based Building Regulations,Internal Report No. 697, National ResearchCouncil of Canada, Ottawa, 1994.

45. Phillips, D., and Kasem, M.A., UpholsteredFurniture Fires in Canada, Consumer andCorporate Affairs Canada, L10127-F32, 1985.

46. Powers, Robert W., Sprinkler Experiencein High Rise Buildings (1969-1979), SFPETechnology Report 79-1, Society of FireProtection Engineers, Boston, MA, 1979.


Bibliography continued

APPENDIX

47. Proulx, Guylene, et al, Study of theOccupant’s Behaviour During the 2 ForestLaneway Fire in North York, Ontario, January 6th, 1995., Internal Report IRC-IR-705, Institute for Research andConstruction, National Research Council of Council, Ottawa, 1995.

48. Puchovsky, Milosh T., et al, NFPA’s Future inPerformance-Based Codes and Standards,National Fire Protection Association, Quincy,MA, 1995.

49. Registry of Product Evaluations, CanadianConstruction Materials Centre, NationalResearch Council of Canada, Ottawa,NRCC No. 36130, Winter 1995 – 1996.

50. Richardson, J.K., An Assessment of thePerformance of Automatic Sprinkler Systems,SFPE Technology Report 84-2, Society ofFire Protection Engineers, Boston, MA, 1984.

51. Robertson, A.F. ed., Fire Standards andSafety, American Society for Testing andMaterials, Special Technical Publication 614,Philadelphia, PA, 1976.

52. Schaffer, E.L., Charring Rates of SelectedWoods Transverse to Grain, Res. Pap. FPL69, USDA Forest Service, Forest ProductsLab., Madison, WI, 1967.

53. Schaffer, E.L., Review of InformationRelated to the Charring Rate of Wood,Res. Note FPL-145, USDA Forest Service,Forest Products Lab., Madison, WI, 1966.

54. Schaffer, E.L., et al, Strength Validation andFire Endurance of Glue-Laminated TimberBeams, Res. Pap. FPL 467, USDA ForestService, Forest Products Lab., Madison, WI,1986.

55. Shorter, G.W., McGuire, J.H., N.B. Hutcheon,and Leggett, R.F., The St. Lawrence Burns,NFPA Quarterly, Vol. 53, No. 4, National FireProtection Association, Boston, MA, 1960.

56. Shoub, H., ed., Early History of Fire EnduranceTesting in the United States, American Societyfor Testing and Materials, Special TechnicalPublication 301, Philadelphia, PA, 1961.

57. Smith, J. Grove, Fire Waste in Canada,Report of the Commission of Conservation,Ottawa, 1918.

58. Solomon, R.E, ed., Automatic SprinklerSystems Handbook, Sixth Edition, NationalFire Protection Association, Quincy, MA, 1994.

59. Standard for Fire Doors and Windows, NFPA 80, National Fire ProtectionAssociation, Quincy, MA, 1992.

60. Standard for the Installation, Maintenanceand Use of Protective Signaling Systems,NFPA 72, National Fire ProtectionAssociation, Quincy, MA, 1990.

61. Standard for the Installation of SprinklerSystems, NFPA 13, National Fire ProtectionAssociation, Quincy, MA, 1994.

62. Standard for the Installation of SprinklerSystems in One-and Two-Family Dwellingsand Mobile Homes, NFPA 13D, National FireProtection Association, Quincy, MA, 1994.

63. Standard for the Installation of SprinklerSystems in Residential Occupancies up toFour Storeys, NFPA 13R, National FireProtection Association, Quincy, MA, 1994.

64. Standard for the Installation of Standpipeand Hose Systems, NFPA 14, National FireProtection Association, Quincy, MA, 1993.

65. Standard for the Installation of Fire AlarmSystems, Underwriters’ Laboratories ofCanada, ULC Standard CAN/ULC S524-M91,Scarborough, Ontario, 1991.

66. Standard for the Verification of Fire AlarmSystems, Underwriters’ Laboratories ofCanada, ULC Standard CAN/ULC S537-M87,Scarborough, Ontario, 1986.

67. Standard Method for Accelerated Weatheringof Fire-Retardant Treated Wood for FireTesting, ASTM D2898, American Society forTesting and Materials, Philadelphia, PA, 1994.

68. Standard Methods of Fire Endurance Testsof Building Construction and Materials,Underwriters’ Laboratories of Canada, ULCStandard CAN4-S101-M89, Scarborough,Ontario, 1982.

69. Standard Method of Fire Tests for FireStop Systems, Underwriters’ Laboratoriesof Canada, ULC Standard CAN4-S115-M85, Scarborough, Ontario, 1985.

Bibliography 343


APPENDIX

70. Standard Method of Fire Test of Exterior WallAssemblies, Underwriters’ Laboratories ofCanada, ULC Standard CAN/ULC-S134-M92,Scarborough, Ontario, 1992.

71. Standard Method of Fire Tests of Light Diffusersand Lenses, Underwriters’ Laboratories ofCanada, ULC Standard ULC-S102.3-M1982,Scarborough, Ontario, 1982.

72. Standard Methods of Fire Tests of RoofCoverings, Underwriters’ Laboratories ofCanada, ULC Standard CAN/ULC-S107-M87,Scarborough, Ontario, 1987.

73. Standard Method of Test for Determination ofDegrees of Combustibility of Building MaterialsUsing an Oxygen Consumption Calorimeter(Cone Calorimeter), Underwriters’ Laboratoriesof Canada, ULC Standard CAN/ULC-S135-92,Scarborough, Ontario, 1992.

74. Standard Method of Test for Determinationof Non-Combustibility in Building Materials,Underwriters’ Laboratories of Canada, ULCStandard CAN4-S114-M80, Scarborough,Ontario, 1980.

75. Standard Method of Test for Fire SpreadUnder Roof-Deck Assemblies, Underwriters’Laboratories of Canada, ULC StandardCAN/ULC-S126-M86, Scarborough,Ontario, 1986.

76. Standard Method of Test for Surface BurningCharacteristics of Building Materials andAssemblies, Underwriters’ Laboratories ofCanada, ULC Standard CAN/ULC-S102-M88,Scarborough, Ontario, 1988.

77. Standard Method of Test for Surface BurningCharacteristics of Flooring, Floor Covering,and Miscellaneous Materials and Assemblies,Underwriters’ Laboratories of Canada, ULC Standard CAN/ULC-S102.2-M88,Scarborough, Ontario, 1988.

78. Standard Test Methods for Fire Tests ofBuilding Construction and Materials, ASTME119-95, American Society for Testing andMaterials, Philadelphia, PA, 1995.

79. Supplement to the National Building Codeof Canada 1990, Associate Committee onthe National Building Code, NationalResearch Council of Canada, Ottawa,NRCC 30629, 1990.

80. Test Methods for Electrical Wires and Cables,CSA C22.2 No. 0.3-92, Canadian StandardsAssociation, Toronto, Ontario, 1992.

81. Thermal Insulation, Mineral Fibre, forBuildings, CSAA101-M1983, CanadianStandards Association, Toronto, Ontario, 1983.

82. U.S. Department of Energy, AutomaticSprinkler System Performance and Reliabilityin United States Department of EnergyFacilities, 1952-1980, Washington, DC, 1982.

83. Users Guide – NBCC 1995 Fire Protection,Occupant Safety and Accessibility (Part3),Canadian Commission on Building and Fire Codes, National Research Council ofCanada, Ottawa, 1996.

84. Walker, John, Disasters, Studio Vista,London, 1973.

85. Williams-Leir, G., Program for PocketCalculator to Derive Spatial Separations toDeter Fire Spread, Computer Program No.44, Division of Building Research, NationalResearch Council of Canada, Ottawa, 1978.

86. Williams-Leir, G., Another Approximation forSpatial Separation, Technical Paper No. 372,Division of Building Research, NationalResearch Council of Canada, Ottawa, NRCC 12643, 1970.

87. Williams-Leir, G., Approximation for SpatialSeparations, NFPA Fire Technology Volume2, No. 2, National Fire ProtectionAssociation, Boston, MA, 1966.

88. Wood Building Technology, CanadianWood Council, Ottawa, 1993

89. Wood Design Manual, Canadian WoodCouncil, Ottawa, 1995.

90. Wood Preservation, CAN/CSA O80 SeriesM89, Canadian Standards Association,Toronto, Ontario, 1989.

91. Wood Reference Handbook, CanadianWood Council, Ottawa, 1995.



APPENDIX

A

Access for fire fighting

See firefighting

Access panels 308-309

Access routes 305-307

Access to exits 282-287

Alarm systems

control facility 327

in suites 281

See also Fire alarms; Fire detection systems

American Society for Testing and Materials (ASTM)

standard re. roof assemblies 222

and testing fire-resistance ratings 147

American Society for Testing Materials (ASTM) Standards

(D-2898) accelerated weathering test 214, 222

(E-108) roof coverings 222

(E-119) fire-resistance ratings 155

(E-84) flame-spread rating 204

Annunciator panels 275-276, 280

Arenas 77, 80

Assembly occupancies. See Group Aoccupancies (assembly)

ASTM. See American Society for TestingMaterials (ASTM)

Atriums

requirements for 131, 185-187

Automatic Sprinkler Systems Handbook (NFPA) 316

B

Basements

See Access for firefighting, below grade; Storeys below ground

Beams 177

Beams, glulam 168-171

See also Heavy timber construction

Bleachers 74

Building

definition 71

classification 73-82

construction requirements 83

See also Design requirement tables

size

building area 75

building height 76-80

exceptions for building height 77-80

major occupancy 80-81

See also Group A, B, C, etc. occupancies

Building codes

fires that shaped 9-15

origin of 3-5

See also National Building Code of Canada

Burning brands 220, 222

Burn rate. See Char

Business and personal services occupancies.

See Group D occupancies

C

Cables 142, 297, 327

Canadian Commission on Building and Fire Codes

formation of 17-18

Public Review Process 19

role of 6, 13

Standing Committee on Fire Protection 18

Canadian Construction Materials Centre (CCMC) 23

Canadian Standards Association (CSA)

heavy timber construction 34

wood-frame construction 32

Canadian Standards Association (CSA) Standards

(0141) Softwood Lumber 34

(080) Wood Preservation 213

(086) Engineering Design in Wood 32, 169

Canadian Wood Council, Wood Design Manual 32, 169

Index 345

Index

APPENDIX

Care and detention occupancies. See Group Boccupancies (care and detention)

CCMC. See Canadian Construction MaterialsCentre (CCMC)

Ceiling membranes

fire-resistance rating 135

component additive method 161-163

Ceilings, basis for fire-resistance rating 157

Ceiling spaces 298

Cellulose 167, 203

Cement board, reinforced 202

Central alarm and control facility 327

Char 33, 168

Cladding and fascias 42-44

Closures

compartmentation 62

protection of openings 135-140

Coatings, as interior finishes 207

Columns, fire-resistance rating 250, 179

Columns, glulam 168-171

Combustible construction


Compartmentation

affect on fire severity 175-176

area of exposing building face 237-238

containing a fire 61-63

definition 133

exposure protection within a building 245-250

See also Fire separations

Component additive method 157-165

Concealed spaces

combustible materials in 39, 59, 199, 297

fire separations 146, 189

fire stopping 39, 104, 163, 189-192

sprinklers 313, 315

Concrete construction 144

Concrete, reinforced 29, 144

Connections

fire service 305, 307

heavy timber construction 34-37

joists for firewalls 145

Construction requirements 83-89

See also Design Requirement Tables

Construction types 98

heavy timber construction 33-38

noncombustible construction 39-47

wood frame construction 31-32, 55-59

Corridors 282, 286-287

Crawl spaces 95-96

See also Storeys below ground

D

Dampers 141

Design requirement tables 97-127

Division of Building Research. SeeInstitute for Research in Construction (IRC)

Doors

fire-resistance rating 138-139

flame-spread rating 210-211

See also Closures; Egress, means of; Exits

Draft stops 186, 277

Dry pipe systems 315

Ducts 13, 58, 135, 141, 163, 297

firewalls 274

Dwelling units 178, 210, 246, 273, 279, 293

E

Eave projections 146, 192, 240

Egress, means of

access to exits 282-287

exits 287-292

floor areas of specific occupancies 293-297

suites 281-282

Electrical conductors, in high buildings 327

Electrical wiring 141-142

Elevators

firefighters’ 326

high buildings 326

Emergency power supply, in high buildings 328

Equivalent opening factor 244

See also Spatial separation


Index continued

APPENDIX

Evacuation

high buildings 323

managing the exposed 67, 267

Exhaust systems, mechanical 186

Existing buildings, application of NBCC. See Upgrading

Exits

means of egress 281-291

occupant load 269-271

width of 289

See also Egress, means of; Evacuation

Exposing building face

area of 237-238

construction of 238-240

fire spread between buildings 227-228

limiting distance 233-235, 251-262

See also Spatial separation

Exterior walls. See Spatial separation; Walls, exterior

Extrapolation of data from fire tests 172-174

F

Finish, interior. See Flame-spread rating; Interior finish

Fire

containing it 61-63

firefighting 65, 303

preventing conflagrations 62-63

description of in a room 55

Fire alarms 273-280

and occupant load 269-271

See also Fire detection systems

Fire compartments See Compartmentation

Fire department connections. See Sprinklers;Standpipe and hose system

Fire detection systems

alarm systems 273-280

fire and smoke detection systems 276-279

smoke alarms 279

See also Fire alarms; Flame detectors; Heat detectors; Smoke detection systems; Smoke alarms

Fire extinguishers, portable 317

Firefighting

access to buildings 305-309

access above grade 308

access below grade 309

fire protection systems

sprinklers 91, 311-316

standpipes 316-317

water supply 316

high buildings 326-327

elevators 326

Fire growth

limiting of 55-59

flammability 58-59

noncombustibility concept 57

Fire hose. See Standpipe and hose systems

Fire load 175-176

Fire modelling 171-172

Fire Protection Handbook (NFPA) 316

Fire-protection ratings, closures 138

Fire protection systems

sprinkler systems 311-316

standpipes 316-317

water supply 316

Fire resistance

and multiple occupancy 83-89

and sprinklers 91-93

Fire-resistance rating

alternative methods for determining 157-174

extrapolating data from tests 172-174

for glulam timbers 168-171

Harmathy’s “Ten Rules of Fire Endurance” 172-174

of atriums 185-187

ceiling assemblies 147-149, 157-165

component additive method 157-165

definition 147, 157

exits 290

exterior walls 149-150, 160

fire separations 133-146, 175

firewalls 144, 158

Index 347

Index continued

APPENDIX

floor assemblies 147-149, 157-165

heavy timber construction 37

history 147

mezzanines 185-187

requirements in NBCC 175-183

exceptions to 182-183

history 175

loadbearing structural elements 179-182

structural assemblies 176-179

roof assemblies 147-149, 157-165

and sound resistance 166-168

of supporting assemblies 87

testing 147-153

alternative test standards 155

availability of test results 153

standard temperature-versus-time curve 152

ULC S101 test method 151

wood-framed buildings 32-33

Fire-resistive construction 9, 29

Fire retardant coatings 214, 222

Fire-retardant treated wood (FRTW)

flame spread 213-214

roof assemblies 217-219

roof coverings 219-222

Fires

examples of ones that shaped building codes 3-4, 9-15

Fire safety, occupant load 269-271

Fire separations 133-146

compartmentation 61-63

continuity of 134-142, 180

protection of openings by closures 135-139

protection of small openings 141-142

corridors 282, 286-287

exits 290

fire-resistance rating 133-146, 175

firewalls 142-146

residential occupancies 178-179

as structural fire protection 131

See also Closures; Compartmentation; Exits; Fire stops; Firewalls; Openings

Fire severity, fire load concept 175-176

Fire stops 189-192

Firewalls

building area 75


fire separations 142-146

Flame detectors 278

Flame-spread rating

combustible materials 58-59

determining 201-206

fire-retardant treated wood 213-214

high buildings 325

interior finishes 207-212

noncombustible construction 209-211

roof assemblies 217-222

wood finishes 205-206

Flammability

determining 201-206

limits placed on 211-212

Flashover 55

Floor areas

assembly occupancies 293

care facilities 294-295

fire compartments 237, 286

garages 295

major occupancy 87

mezzanines 77-80

residential occupancies 293-294

service spaces 295-299

Flooring

flame-spread rating 208

wood in noncombustible construction 45

Foamed plastics


insulation 39, 58

Framing, wood or light steel 160

FRTW. See Fire-retardant treated wood (FRTW)


Index continued

APPENDIX

Furnaces

Steiner tunnel 201-203

testing fire-resistance ratings 147-151

Furring

fire stopping 191

use of wood in noncombustible construction 40-41

Fusible links, doors in fire separations 139

G

Gables 240

Garages

firewalls 145-146

unprotected openings 243

Glass

blocks 244

and fire separations 139

wired, area of unprotected openings 244

Glazing, solid 77

Glue-laminated timber beams and columns. See Glulam

Glulam

fire resistance 168-171

See also Heavy timber construction

Grade, building height 76-77

Group A occupancies (assembly)


design requirement tables 99-106


Group B occupancies (care and detention)

alarm systems 274, 277



use of wood partitions in 45

Group C occupancies (residential)

alarm systems 274, 277



fire separation 178

sprinkler systems for 312-313

Group D occupancies (business and personal services)



Group E occupancies (mercantile)




Group F occupancies (industrial)

alarm systems 274




Gypsum board

fire-resistance rating 150, 153, 159-160, 167


in noncombustible construction 39

as a protective finish 32

H

Harmathy, Dr. Tibor, “The Ten Rules of Fire Endurance” 172-174

Hazardous Products Act 51

Heat detectors 276

Heavy timber construction 33-38

definition 33

fire-resistance rating 37, 181, 194

roofs 194

High building

evacuation 13-15

firefighting 65, 326-327

fire safety in 323-328


problems of fires in 13-15

smoke control systems 323-325

smoke developed classification 59, 325

wood finishes 47

Horizontal assemblies 147-148

Horizontal service spaces. See Ceiling spaces

Index 349

Index continued

APPENDIX

I

Increased area of openings 244

Industrial occupancies. See Group F occupancies (industrial)

Institute for Research in Construction (IRC) 6, 151

Codes Centre 18-19

Insulation, and fire-resistance ratings 159, 161, 167

Interconnected floor spaces 185-187


fire separations 238

See also Atriums; Mezzanines

Interior finishes 207-212

application of NBCC requirements 209-212

fire-retardant treated wood 213-215

fire-test methods 201-204

high buildings 325

See also Flame-spread rating

IRC. See Institute for Research in Construction (IRC)

L

Light fixtures, flame-spread rating for 208-209

Limiting distance 233-241

examples of calculations 251-263

See also Spatial separation, Exposing building face

Loadbearing structural elements 179-182

M

Major occupancy 80-82

Means of egress. See Egress, means of

Mercantile occupancies. See Group E occupancies (mercantile)

Mezzanines


fire protection requirements 185-18

Millwork 44

N

National Building Code of Canada (NBCC)

Appendix B

smoke control 325

Appendix D

fire resistance 157-165, 168-171


assumptions and objectives 51-67

development 17-21

history 3-4

objective-based requirements 23-25

prescriptive requirements 23

relationship with NFCC 20-21

National Fire Code of Canada (NFCC) 20-21

National Fire Protection Association (NFPA) 6-7

Automatic Sprinkler Systems Handbook 316

Fire Safety Concepts Tree 52-54

National Fire Protection Association (NFPA) Standards

(13) Installation of Sprinkler Systems 312-315

(13D) residential sprinkler systems 312

(13R) residential sprinkler systems 312

(14) Installation of Standpipe and Hose Systems 317

(255) interior finishes 204

(257) roof coverings 222

(72D) ... Proprietary Protective Signalling Systems 280

(80) Standard for Fire Doors and Windows 137-138

National Research Council of Canada (NRC) 6, 18

Institute for Research in Construction 151

NBCC. See National Building Code of Canada (NBCC)

NFCC. See National Fire Code of Canada (NFCC)


Index continued

APPENDIX

NFPA. See National Fire Protection Association (NFPA)

Noncombustibility

definition 39

test 56-59

Noncombustible construction

definition 55


use of wood in 39-47

cladding and fascias 42-44

fire stops 41

flooring elements 45

millwork 44

roofs 41

stairs and storage lockers 46

window sash and frames 41

wood finishes 46-47

wood furring 40-41

wood partitions 45-46

NRC. See National Research Council ofCanada (NRC)

O

Occupancies

construction requirements 83-89

design requirement tables for 97-127

safety within floor areas 293-295

See also Building classification; Group A, B, C, etc. occupancies

Occupancy

major

alarm systems 273

definition 80-82

separation 84-86

multiple

fire alarm systems 274

subsidiary 81

Occupant load 269-271

Openings

closures 135-140

protection of small 141-142

See also Closures; Interconnected floor spaces

P

Paint. See Coatings

Parapets

roofs 144-145

wood furring 41

Partitions

fire separations 149

wood 45-46

Performance-based requirements 51

Pipes 141

Plastics, foamed. See Foamed plastics

Plywood

fire-retardant treated 219

fire stopping 189-192

Prescriptive requirements 51, 176

Pressurization 324-325

Prevention of fire-spread between buildings.See Spatial separation

Proprietary control centres 280

Protected floor space 185

Provincial/Territorial Committee on BuildingStandards (PTCBS) 6

PTCBS. See Provincial/Territorial Committee on Building Standards (PTCBS)

Public corridors. See Corridors

R

Radiation

adjacent buildings 227-231

exterior walls 183

through openings 62, 238, 244

Rehabilitation, of old buildings. See Upgrading

Residential occupancies. See Group C occupancies (residential)

Roof assemblies

fire-resistance rating 157-159

sprinklers 92-93, 194

fire-retardant treated wood

Index 351

Index continued

APPENDIX

roof systems 218-219

flame spread 217-218


Roof coverings. See Roof assemblies

Roofs

decking 217

firewalls 144

use of wood 41

See also Soffits

Roof-top enclosures 298-299

S

St. Lawrence Burns 227

Separations, fire. See Fire separations

Service spaces 297-299

Shafts 135, 137

Shakes. See Roof assemblies

Shingles. See Roof assemblies

Siding. See Spatial separations; Walls, exterior

Single-stage fire alarm systems 274

Smoke

alarms 279

See also Fire alarms; Fire detection systems; Smoke detectors

control in high buildings 323-325

detection systems 276-279

Smoke developed classification

definition 59

high buildings 325

tests for interior finishes 201-203

Soffits 246-247

Sound Transmission Classification (STC) 166-168

Spatial separation

examples of calculations 251-263

exceptions to requirements 243-244

equivalent opening factor 244

increased area of openings 244

exposure protection within a building 245-250

fire spread between buildings 227-231

limiting distance 233-241

Sprinklers

building area 91-92

changes in the 1995 NBCC 91-93

as fire protection system 91-93, 193-194, 311-317

high buildings 323

increased area of unprotected openings 231

mezzanines and atriums 185-186

systems 311-317

travel distances 290

Stack effect 13, 59, 324

Stairs 46, 191

Standards Council of Canada 23

Standard time-versus-temperature curve 152

See also Fire-resistance rating

Standpipe and hose system 305, 316-317

Steel 29-30


studs, wall assemblies 158

Steiner tunnel

testing interior finishes 201-203

testing roof assemblies 217

Storage rooms, lockers 46, 276

Storeys below ground level 95-96

Streets, construction requirements 88

Suites 281

See also Access to exits

T

Tall buildings. See High buildings

Tar. See Roof assemblies

Tests

combustibility 56-58

fire alarm systems 275

fire-protection rating for closures 138

fire resistance 147-153


interior finishes 201-204


smoke developed classification 201-204

See also ASTM Standards; CSA Standards; NFPA Standards; ULC Standards


Index continued

APPENDIX

Thermal barriers 43, 208, 218

Thermoplastic materials 204

Tiles. See Roof assemblies

Time-temperature curve. See Standard time-versus-temperature curve

Travel distance 285-287, 290

Two-stage fire alarm systems 274

U

ULC

“Criteria for Use in Extension of Data from Fire Endurance Tests” 173

ULC Standards

(CAN4, S113) Standard Specification for Wood Core Doors Meeting the Performance Required... 138

(CAN4-S104) Standard Method for Fire Tests of Door Assemblies 138

(CAN4-S115) Standard Method of Test of Fire Stop Systems 142

(CAN/ULC-S101) Standard Method of Fire Endurance Tests of Building Construction... 151-153, 327

(CAN/ULC-S102.2) StandardMethod of Test for Flooring, Floor Covering,... 203-204

(CAN/ULC-S102.3) Standard Method of Fire Tests of Light Diffusers and Lenses 209

(CAN/ULC-S102) Standard Method of Test for Building Materials and Assemblies 202-204

(CAN/ULC-S107) Standard Methods of Test of Roof Coverings 220, 222

(CAN/ULC-S114) Standard Method of Test for Determination of Noncombustibility of Materials 56

(CAN/ULC-S126) Standard Method of Test for Fire Spread Under Roof-Deck Assemblies 217-219

(CAN/ULC-S127) “The corner wall test” 204

(CAN/ULC-S134) Standard Method of Fire Test of Exterior Wall Assemblies 43

(CAN/ULC-S524) Standard for the Installation of Fire Alarm Systems 275

(CAN/ULC-S537) Standard for the Verification of Fire Alarm Systems 275

UL Standards, (790) roof coverings 222

Underwriters’ Laboratories Inc.

fire-test methods 201

standard re. roof assemblies 220

testing fire-resistance ratings 153

Underwriters’ Laboratory of Canada. See ULC

Unprotected openings

equivalent opening factor 244

exposing building faces 238-239, 243

fire spread between buildings 229-231, 234-235

increased area of openings 244

See also Openings; Spatial separation

Unsprinklered areas. See Sprinklers

Unusual structures 317

Upgrading

NBCC and upgrading of existing buildings 20

occupant load 269

V

Varnish. See Coatings

Vaults 182

Veneer 207

Venting

and fire severity 176

high buildings 13, 324, 327

smoke detectors in air circulation system 277

Vertical service space 297-298

Vertical shafts 13, 135, 297

Vestibules 185, 324-325

Vibration control 32

Voice communication system 327

W

Wallboard 159-160

Wallpaper. See Coatings

Index 353

Index continued

APPENDIX

Walls

exposing building faces 235, 237-240

fire-resistance rating 158, 161, 164

fire-resistance ratings 149-150, 166-168

in noncombustible buildings 42-43

Warnock Hersey Professional Services Ltd. 153

Water supply

as fire protection system 311

for sprinkler systems 311-312

Weathering 44, 214, 222

Window, sash and frames 41

Wired glass. See Glass

Wood

advantages of 29


in noncombustible buildings 39-47

in service spaces 296

Wood Design Manual (Canadian Wood Council) 32, 169

Wood finishes 46-47, 207-210

Wood-frame construction

definition 31-33

fire-resistance rating,

Group C occupancy buildings 179

loadbearing structural elements 179-180

fire stops 189-191

Wood partitions in noncombustible buildings

Wood, structural systems in

heavy timber construction. See Heavy timber construction

wood-frame construction. See Wood-frame construction


Index continued

APPENDIX

2.1

[2.1.6.1.] 145

[2.1.6.2.] 76

2.5

[2.5.3.1.] 204, 222

3.1

[3.1.3.1.] 85

[3.1.4.2.] 208

[3.1.4.4.] 46, 213

[3.1.4.5.] 37

[3.1.4.6.] 34, 37, 38, 194

[3.1.5.] 321

[3.1.5.2.] 41, 58

[3.1.5.3.] 41, 221

[3.1.5.4.] 41

[3.1.5.5.] 42-43, 44, 58, 214

[3.1.5.6.] 40

[3.1.5.7.] 44

[3.1.5.8.] 45, 208

[3.1.5.9.] 46

[3.1.5.10] 46, 209, 210

[3.1.5.12.] 45

[3.1.5.13.] 46

[3.1.5.17.] 142

[3.1.5.19.] 142

[3.1.7.1.] 151, 157

[3.1.7.2.] 150, 244

[3.1.7.3.] 147, 161, 168, 240

[3.1.7.4.] 182

[3.1.7.5.] 87, 179, 194

[3.1.8.1.] 61-62, 134

[3.1.8.3.] 135

[3.1.8.4.] 137

[3.1.8.4.] 138

[3.1.8.6.] 137-138, 144, 194

[3.1.8.7.] 141

[3.1.8.8.] 141

[3.1.8.10.] 138

[3.1.8.11.] 139

[3.1.8.12.] 139

[3.1.8.15.] 138

[3.1.9.] 134

[3.1.9.1.] 142

[3.1.9.2.] 142

[3.1.9.3.] 142

[3.1.9.4.] 141, 194

[3.1.10.] 144

[3.1.10.1.] 145, 146

[3.1.10.2.] 146

[3.1.10.3.] 146

[3.1.10.4.] 146

[3.1.10.5.] 138, 144, 146

[3.1.10.7.] 146

[3.1.11.1.] 189

[3.1.11.5.] 189, 194

[3.1.11.6.] 96

[3.1.11.7.] 189

[3.1.12.1.] 202-203, 58

[3.1.13.] 58

[3.1.13.1.] 207

[3.1.13.2.] 46, 210, 290, 298

[3.1.13.4.] 209

[3.1.13.6.] 47, 210

[3.1.13.7.] 47, 59, 208, 298, 325

[3.1.13.8.] 209-210, 214

[3.1.14.1.] 218

[3.1.14.2.] 218

[3.1.15.1.] 220

[3.1.15.2.] 221-222

3.1.16.1. 269-271

3.2

[3.2.1.1.] 77, 79, 80, 297-298

[3.2.1.2.] 95

[3.2.1.5.] 95

[3.2.2.3.] 182

Index of Code References 355

Index of Code References

APPENDIX

[3.2.2.5.] 83

[3.2.2.6.] 82

[3.2.2.7.] 82-83, 85-87

[3.2.2.8.] 87

[3.2.2.9.] 96

[3.2.2.10.] 305, 307

[3.2.2.14.] 77, 299

[3.2.2.15.] 95, 309

[3.2.2.16.] 39, 93, 194

[3.2.2.20.] 99

[3.2.2.21.] 100

[3.2.2.22.] 100

[3.2.2.23.] 101

[3.2.2.24.] 101

[3.2.2.25.] 102

[3.2.2.26.] 102

[3.2.2.27.] 103

[3.2.2.28.] 103

[3.2.2.29.] 104

[3.2.2.30.] 104

[3.2.2.31.] 104

[3.2.2.32.] 105

[3.2.2.33.] 105

[3.2.2.34.] 105

[3.2.2.35.] 106

[3.2.2.36.] 107

[3.2.2.37.] 107

[3.2.2.38.] 108

[3.2.2.39.] 108

[3.2.2.40.] 109

[3.2.2.41.] 109

[3.2.2.42.] 110

[3.2.2.43.] 83, 111

[3.2.2.44.] 75, 111

[3.2.2.45.] 112

[3.2.2.46.] 113

[3.2.2.47.] 75, 113, 178

[3.2.2.48.] 113

[3.2.2.49.] 89, 114

[3.2.2.50.] 89, 114

[3.2.2.51.] 114

[3.2.2.52.] 115

[3.2.2.53.] 89, 116, 177

[3.2.2.54.] 88, 116

[3.2.2.55.] 116

[3.2.2.56.] 116

[3.2.2.57.] 83, 117

[3.2.2.58.] 117

[3.2.2.59.] 118

[3.2.2.60.] 118

[3.2.2.61.] 118

[3.2.2.62.] 118

[3.2.2.63.] 119

[3.2.2.64.] 119

[3.2.2.65.] 120

[3.2.2.66.] 120

[3.2.2.67.] 121

[3.2.2.68.] 121

[3.2.2.69.] 122

[3.2.2.70.] 122

[3.2.2.71.] 122

[3.2.2.72.] 122

[3.2.2.73] 123

[3.2.2.74.] 123

[3.2.2.75.] 123

[3.2.2.76.] 124

[3.2.2.77.] 124

[3.2.2.78.] 124

[3.2.2.79.] 124

[3.2.2.80.] 125

[3.2.2.81.] 125

[3.2.2.82.] 126

[3.2.2.83.] 127

[3.2.3.] 230

[3.2.3.1.] 62, 65, 230-231, 234-235, 244

[3.2.3.2.] 237-238

[3.2.3.3.] 240

[3.2.3.5.] 235


Index of Code References continued

APPENDIX

[3.2.3.6.] 240

[3.2.3.7.] 43, 231, 238, 244, 252

[3.2.3.8.] 240

[3.2.3.9.] 243

[3.2.3.10.] 243

[3.2.3.11.] 231, 244

[3.2.3.12.] 249-250

[3.2.3.13.] 245

[3.2.3.14.] 247

[3.2.3.15.] 192, 246-247

[3.2.3.16.] 248-249

[3.2.4.1.] 273, 275

[3.2.4.2.] 274-275

[3.2.4.3.] 274

[3.2.4.4.] 274

[3.2.4.5.] 275

[3.2.4.7.] 92, 186, 279-280

[3.2.4.8.] 275-276

[3.2.4.9.] 88, 186, 280

[3.2.4.10.] 277

[3.2.4.11.] 186, 277

[3.2.4.12.] 277

[3.2.4.15.] 279

[3.2.4.17.] 276

[3.2.4.21.] 279

[3.2.4.22.] 327

[3.2.5.] 65

[3.2.5.1.] 308

[3.2.5.2.] 308

[3.2.5.4.] 305, 311

[3.2.5.5.] 305-307, 311

[3.2.5.6.] 305

[3.2.5.7.] 311

[3.2.5.8.] 316

[3.2.5.9.] 317

[3.2.5.10.] 316-317

[3.2.5.11.] 317

[3.2.5.13.] 312-314

[3.2.5.14.] 315

[3.2.5.16.] 307

[3.2.5.17.] 317

[3.2.6.1.] 321

[3.2.6.2.] 324

[3.2.6.4.] 326

[3.2.6.5.] 326

[3.2.6.6.] 326

[3.2.6.7.] 327

[3.2.6.8.] 327

[3.2.6.9.] 327

[3.2.6.10.] 327

[3.2.7.8.] 328

[3.2.7.9.] 328

[3.2.8.] 80, 185

[3.2.8.1.] 185

[3.2.8.2.] 79, 185, 187

[3.2.8.3.] 185

[3.2.8.4.] 185

[3.2.8.5.] 185

[3.2.8.6.] 186

[3.2.8.7.] 186

[3.2.8.8.] 187

[3.2.8.9.] 187

3.3

[3.3.1.3.] 282

[3.3.1.4.] 134, 286-287

[3.3.1.5.] 283, 285

[3.3.1.6.] 285

[3.3.1.9.] 287

[3.3.1.22.] 282

[3.3.2.2.] 293

[3.3.2.3.] 293

[3.3.2.4.] 293

[3.3.2.5.] 314

[3.3.2.9.] 293

[3.3.3.5.] 294

[3.3.4.2.] 179, 293-294

[3.3.4.4.] 293

Index of Code References 357


APPENDIX

[3.3.5.4.] 295

[3.3.5.5.] 295

[3.3.5.6.] 85, 295

3.4

[3.4.2.1.] 67, 288

[3.4.2.3.] 288

[3.4.2.4.] 285-286

[3.4.2.5.] 282, 289-290

[3.4.3.] 62

[3.4.3.1.] 289

[3.4.3.3.] 185

[3.4.3.4.] 289

[3.4.3.5.] 289

[3.4.4.1.] 288, 290

[3.4.4.3.] 250

[3.4.4.4.] 290

[3.4.5.1.] 290

[3.4.6.] 288

3.6

[3.6.1.1.] 297

[3.6.2.] 297

[3.6.3.1.] 297

[3.6.3.3.] 298

[3.6.4.2.] 135

[3.6.5.4.] 298

Appendix A

[A-9.23.4.2.] 32

[A-9.10.3.1.A] 153, 160, 166-167

[A-9.10.3.1.B] 166, 168

Appendix D

[D-2.11.] 37

[D-2.3.] 157

[D-2.3.1.] 158

[D-2.3.2.] 158

[D-2.3.3.] 161

[D-2.3.4.] 158-160

[D-2.3.5.] 159, 161

[D-2.3.6.] 158, 161

[D-2.3.10.] 163

[D-2.3.11.] 163

[D-2.3.12.] 161, 163

[D-2.4.] 163

[D-2.11.2.] 168

[D-3.1.1.] 204, 210, 325



APPENDIX

fire safety design in buildings - canadian wood council · title: fire safety design in buildings...

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