Continuing

Education

Services

Concrete Masonry and Mold

Program #: 000515 NCMA

Continuing

Education

Services This program is registered with the AIA/CES for

continuing professional education. As such, it does not

include content that may be deemed or construed to be an

approval or endorsement by the AIA of any material of

construction or any method or manner of handling, using,

distributing, or dealing in any material or product.

Questions related to specific materials, methods, and

services will be addressed at the conclusion of this

presentation.

AIA Disclaimer Notice

Continuing

Education

Services

Is Concrete Masonry the Solution to Mold?

Continuing

Education

Services

Benefits of Concrete Masonry

•Form and function

•Versatile designs

•Long-term durability

•Fire-resistant

•Energy efficient

•Sound insulation

•Strength

And - does not provide a

source of food for mold

growth.

Continuing

Education

Services

Overview

•What is mold?

•Why the fuss?

•How should concrete masonry be

designed and constructed to limit mold

growth potential?

Continuing

Education

Services

What is Mold?

• Members of the Fungi Kingdom –

Neither plant nor animal.

• Mold Spores – They are everywhere!

Sizes from 3 to 40 Microns (human hair

is 100- 150 microns). 250,000 can fit on

head of a pin.

Continuing

Education

Services

Types of Mold

• More than 100,000 known species

worldwide.

• Most types found in homes and buildings

are not harmful to people.

• Harmful types include:

– Stachybotrys Chartarum

– Aspergillius versicular

– Various species of penicillium

• Most harmful when they become airborne

(such as in air handling systems).

Black mold - requires high

levels of moisture, and

cellulose containing materials.

Greenish-black. Slimy and wet

to the touch.

Continuing

Education

Services

Requirements for Mold Growth

• Food Source – Any organic substance.

• Moisture – Free water or high relative humidity (greater than 70%).

• Hospitable Growing Conditions – Temperature between 40 and 100F, oxygen, darkness, etc.

• Mold Spores – Located everywhere.

Continuing

Education

Services

Health Effects

• Possible reactions:

– Runny nose, headaches, sinus infections, coughs,

watery eyes, breathing difficulties, and general

discomfort.

– Asthmatic symptoms: labored breathing, chest

constriction and coughing.

– Rash

• Prolonged exposure reactions

– Chronic fatigue, dizziness, shortness of breath,

headaches, and nosebleeds. Also muscle cramps,

inability to concentrate, and edema.

Continuing

Education

Services

Litigation Issues

• As many as 60,000 outstanding cases.

• About $780 million in claims paid in 2001

(75% in Texas).

• Basis for lawsuits:

– professional malpractice and negligence for

construction defects and defective designs

– fraud and failure to disclose problems at time

of sale of the property

Continuing

Education

Services

Insurance Response

“The costs of cleaning up mold caused by water from a

burst pipe are covered under the policy because water

damage from a burst pipe is a covered peril. But mold

caused by water from excessive humidity, leaks,

condensation or flooding is a maintenance issue for the

property owner, like termite or mildew prevention, and is

not covered by the policy.”

- Dr. Robert Hartwig

Insurance Information Institute

Also, insurance companies in many states

are not writing new policies.

Continuing

Education

Services

Learning Curve

Why the recent increase in observed mold

infestation…

• Media/public awareness?

• Tighter construction?

• Use of more moisture-sensitive

materials?

• Non-uniform pressurization of buildings?

• Increased construction pace?

Continuing

Education

Services

Mold in Schools

Chavez Elementary School - Madison, Wisconsin • First new public elementary school in Madison in 30 years.

• Air quality complaints led to finding sizeable mold blooms in 1/3 of

the school’s rooms.

•$1.5 million mold and remediation program

Continuing

Education

Services

Building Code Requirements

For controlling mold, esoteric at best…

Keep in mind building codes address

minimum life safety requirements.

Continuing

Education

Services

Building Code Requirements

• Model codes do not contain words “mold

resistant”

• Codes do address minimum conditions which

could produce mold and associated effects.

– Proper ventilation required.

– Exterior envelopes must have vapor retarders, water-

resistive barriers, and flashings.

• International Property Maintenance Code

includes requirements for maintaining viability

and safety.

Continuing

Education

Services

Options for Limiting Mold Growth

• Limit Food Source – Nearly impossible. Reduce use of paper and wood - but still can grow on oil and dust on non-food surfaces.

• Limit Moisture – A logical strategy. Good construction details to reduce free water. Reduce humidity since people prefer 40-50% anyway.

• Provide Inhospitable Conditions – Tough. Hospitable environments provide the temperatures and oxygen. Darkness enables growth in areas that can no be seen.

• Eliminate Mold Spores – Impossible.

Continuing

Education

Services

Options for Limiting Mold Growth

• Air conditioner operation

• A/C selection

• A/C sizing

• Thermostat set point/ceiling fans

• Interior doors

• Space pressurization

• Measure RH in home

• No vinyl wallpapers

• Return air pathways

• Bathrooms

• No open windows or whole

house fans during humid

weather (esp at night)

• A/C maintenance

• Exterior water management

• Repair small leaks

• Water damage

• Moisture condensation

• Exhaust fans

• Closets

• House plants

• Construction moisture

• Unvented attics

• Central dehumidification

• Consider a/c with variable

speed air handlers and with

enhanced dehumidification

mode

Continuing

Education

Services

Mold

Continuing

Education

Services

Is Mold Present?

• Musty smell

• Pink or yellow splotches on vinyl wall

cover

Continuing

Education

Services

Eliminate the Moisture

Exterior

• Rain

• Vapor

Interior

• Vapor

• Air

Keeping indoor

relative humidity low

will decrease dew-

point temperatures,

reducing chance of

condensation.

Also - ensure

continuation of

insulation and air and

vapor retarders.

Continuing

Education

Services

Moisture in Building Materials

Be careful of

sealing in moisture

that is present

within building

materials.

Continuing

Education

Services

Associated Effects of Moisture

• Efflorescence

• Corrosion of Metals & Reinforcing

• Staining/Mold/Mildew

• Leaks

• Rotting & Disintegration of

Insulation/Wood/etc.

Continuing

Education

Services

Keys to Providing

Moisture Penetration Resistance

• Quality Materials

• Good Design and

Detailing

• Good Construction

Continuing

Education

Services

Construction Materials: Concrete Masonry Units

ASTM C 90 Properties

• Compressive

Strength

• Absorption

• Dimensional

Tolerances

• Density

Definitions

• Linear Drying

Shrinkage

Properties Not in C 90

– Color

– Texture

– Density

– Water Repellency

– Fire Ratings

– Thermal Properties

– Sound Properties

Continuing

Education

Services

Which Mortar is the Best?

Cement/Sand

Mortar

Sand/Lime

Mortar Optimum

Range

•Workability

•Water Retentivity

•Late Strength

•Autogenous Healing

•Strength

•Early Setting

•Bond

•Durability

O N S M

ASTM C 270 Mortar Selection Guide:

• Exterior walls – Type N (alternatively S or M)

• Below grade – Type S (alternatively M or N)

Continuing

Education

Services

Barrier Single-Wythe Cavity

Design Considerations:

Basic Concrete Masonry Wall Types

Continuing

Education

Services

Barrier Wall

• Collar joint between wythes acts a barrier to moisture along with the thickness of the wall

• Examples

– Brick and Block Composite Wall

– Solid Grouted CMU Wall

Continuing

Education

Services

Cavity Wall

Air Space: Clear and free and 2 in. minimum

Continuing

Education

Services

Rain Screen Wall

• Equalizes pressure within cavity

• Vents at top and bottom of wall or panel

• Flashing and weep holes

• Compartmentalized

• Allows for ventilation and evaporation

Continuing

Education

Services

Components for Moisture Mitigation

• Flashing

• Weeps

• Vents

• Water Repellent Admixtures

• Sealants & Coatings

• Vapor Retarders

Successful

Mitigation

Requires

Consideration

of ALL

Components

Continuing

Education

Services Level of

Defense

1

2

3

Surface Protection

• Mortar Joints

• Sealants /Coatings

Internal Protection

• Integral Water Repellents

Drainage

• Flashing, weeps and vents

Defense Mechanism

Best Performance Is Achieved

By Redundancy

Vapor

Barriers

Continuing

Education

Services

Surface Protection:

Clear Surface Treatments

• Acrylics - form elastic film over surface.

Quick drying. $

• Silicone Resins - good penetration.

Drying time 4-5 hours. $

• Silanes - good penetration. More volatile.

Can be applied to damp surfaces. $$

• Siloxanes - similar benefits of silanes.

Effective on wider variety of surfaces. $$

Continuing

Education

Services

Surface Protection:

Opaque Surface Treatments

• Portland Cement Plaster (Stucco) - Cementitious

coating. $$

• Cement-Based Paint - good durability (including

alkalis). Fills small voids. $

• Latex Paint - water based. Good durability

(including alkalis). Breathable. Applied to damp

or dry surfaces and cure quickly. Good hiding

characteristics. $

• Alkyd Paints - Durable, flexible, quick dry. Low

alkali resistance. $

Continuing

Education

Services

Internal Protection:

Integral Water Repellents

If the surface barrier compromised, moisture

can move through the wall by:

• gravity

• pressure

• capillary action

Continuing

Education

Services

Integral Water Repellents

• Polymeric material which does not alter

the finished appearance of the block.

• Lasts the lifetime of the unit.

• Cuts down on possibility of

efflorescence.

• Incorporate a compatible integral water

repellent admixture into the mortar.

Continuing

Education

Services

Drainage:

Flashing Material Options

• Sheet Metals

• Composite Materials

• Plastic and Rubber Compounds

Continuing

Education

Services

Durable,

non staining

Flexible, durable,

easy to work with

Easy to paint and

durable

Hard to form

Damaged by

excessive flexing

and can stain

Corrodes early in

acidic and salty air

Advantages Disadvantages

Flashing Materials Metals

Stainless

Steel

Cold-Rolled

Copper

Galvanized

Steel

Durable,

non staining

Flexible, durable,

easy to work with

Easy to paint and

durable

Hard to form

Damaged by

excessive flexing

and can stain

Corrodes early in

acidic and salty air

Material Advantages Disadvantages

Continuing

Education

Services

EPDM

Rubberized

asphalt

Flexible, easy to

form, non-staining

Fully adhered, self

healing, flexible,

easy to form and

join

Aesthetics, full

support

recommended

Full support required, degrades in UV light, metal drip edge required

Material Advantages Disadvantages

Flashing Materials Plastic and Rubber Compounds

Continuing

Education

Services

PVC Easy to form and

join, non-

staining, low cost

Easily damaged,

full support

required, metal

drip edge

required,

questionable

durability

Material Advantages Disadvantages

Flashing Materials Plastic and Rubber Compounds

Continuing

Education

Services

Flashing Locations

Needed anywhere the downward vertical

path of water to the weeps is interrupted:

• Base and foundation

• Lintels

• Bond beams

• Parapets

• Intermediate roofs

Continuing

Education

Services

Flashing Detail at

Reinforced Cell

Typical detail at inside of faceshell

b) Unreinforced cell

of washed pea stone. Alt. — leave out every other reduced size facing unit on top of flahing to serve as cleanouts unitl the wall is completed.* Cavity filter is any material used in conjunction with mortar nets to prevent mortar droppings from cloggin the weeps, i.e. filter paper or 2 in. (51 mm)

a) Reinforced cell

off to fit (typ. a & c)and part of webs cut

Cavity filter*

o.c. partially open2 ft. 8 in. (813 mm)Weep holes @

(typ. b & c)

1 in. (25 mm)

joints"L-shaped" head

Architectural unitwith inside faceshell

Edge of flashing

Solid unit or

Cavity filter*

from joint

to support flashingfilled hollow unit

sealed by mortar

1 in.

e) One-piece flashing

d) Two-piece flashing

Bond beam, lintel orfoundation (typ.)

c) Optional unreinforced masonry

4 in. (102 mm) unit

Drip edge (typ.)

48 in. (1219 mm) o.c.#5 (#16) min. @

Mortar net*

(25 mm)

Flashing

inside of faceshellStop flashing at

> 8 in. (203 mm) wall4 in. (102 mm) unit for8 in. (203 mm) wall,3 in. (76 mm) unit for

Continuing

Education

Services

Flashing Detail at

Unreinforced Cell

Typical detail at inside of faceshell

b) Unreinforced cell

of washed pea stone. Alt. — leave out every other reduced size facing unit on top of flahing to serve as cleanouts unitl the wall is completed.* Cavity filter is any material used in conjunction with mortar nets to prevent mortar droppings from cloggin the weeps, i.e. filter paper or 2 in. (51 mm)

a) Reinforced cell

off to fit (typ. a & c)and part of webs cut

Cavity filter*

o.c. partially open2 ft. 8 in. (813 mm)Weep holes @

(typ. b & c)

1 in. (25 mm)

joints"L-shaped" head

Architectural unitwith inside faceshell

Edge of flashing

Solid unit or

Cavity filter*

from joint

to support flashingfilled hollow unit

sealed by mortar

1 in.

e) One-piece flashing

d) Two-piece flashing

Bond beam, lintel orfoundation (typ.)

c) Optional unreinforced masonry

4 in. (102 mm) unit

Drip edge (typ.)

48 in. (1219 mm) o.c.#5 (#16) min. @

Mortar net*

(25 mm)

Flashing

inside of faceshellStop flashing at

> 8 in. (203 mm) wall4 in. (102 mm) unit for8 in. (203 mm) wall,3 in. (76 mm) unit for

Continuing

Education

Services

Detail at Inside Face Shell

Typical detail at inside of faceshell

b) Unreinforced cell

of washed pea stone. Alt. — leave out every other reduced size facing unit on top of flahing to serve as cleanouts unitl the wall is completed.* Cavity filter is any material used in conjunction with mortar nets to prevent mortar droppings from cloggin the weeps, i.e. filter paper or 2 in. (51 mm)

a) Reinforced cell

off to fit (typ. a & c)and part of webs cut

Cavity filter*

o.c. partially open2 ft. 8 in. (813 mm)Weep holes @

(typ. b & c)

1 in. (25 mm)

joints"L-shaped" head

Architectural unitwith inside faceshell

Edge of flashing

Solid unit or

Cavity filter*

from joint

to support flashingfilled hollow unit

sealed by mortar

1 in.

e) One-piece flashing

d) Two-piece flashing

Bond beam, lintel orfoundation (typ.)

c) Optional unreinforced masonry

4 in. (102 mm) unit

Drip edge (typ.)

48 in. (1219 mm) o.c.#5 (#16) min. @

Mortar net*

(25 mm)

Flashing

inside of faceshellStop flashing at

> 8 in. (203 mm) wall4 in. (102 mm) unit for8 in. (203 mm) wall,3 in. (76 mm) unit for

Continuing

Education

Services

Optional Flashing Detail at

Unreinforced Cell

Typical detail at inside of faceshell

b) Unreinforced cell

of washed pea stone. Alt. — leave out every other reduced size facing unit on top of flahing to serve as cleanouts unitl the wall is completed.* Cavity filter is any material used in conjunction with mortar nets to prevent mortar droppings from cloggin the weeps, i.e. filter paper or 2 in. (51 mm)

a) Reinforced cell

off to fit (typ. a & c)and part of webs cut

Cavity filter*

o.c. partially open2 ft. 8 in. (813 mm)Weep holes @

(typ. b & c)

1 in. (25 mm)

joints"L-shaped" head

Architectural unitwith inside faceshell

Edge of flashing

Solid unit or

Cavity filter*

from joint

to support flashingfilled hollow unit

sealed by mortar

1 in.

e) One-piece flashing

d) Two-piece flashing

Bond beam, lintel orfoundation (typ.)

c) Optional unreinforced masonry

4 in. (102 mm) unit

Drip edge (typ.)

48 in. (1219 mm) o.c.#5 (#16) min. @

Mortar net*

(25 mm)

Flashing

inside of faceshellStop flashing at

> 8 in. (203 mm) wall4 in. (102 mm) unit for8 in. (203 mm) wall,3 in. (76 mm) unit for

Continuing

Education

Services

Good Flashing Detail

Continuing

Education

Services

Poor Detail

Continuing

Education

Services

Drip Edge

Continuing

Education

Services

End Dams

Continuing

Education

Services

Weep Holes

At 32 inches max.

Continuing

Education

Services

Weep Holes

• Cotton sash cord

for drainage path

(remove after wall

is laid up)

• Partially open

head joints

(preferred)

Continuing

Education

Services

Products & Workmanship Tying it all Together

• The quality and compatibility of material

components and care in installation are key to

wall performance.

• The recommended specification

for products and workmanship

for masonry construction are

covered in the latest edition of

Masonry Standards Joint

Committee ACI 530.1/ASCE

6/TMS 602

Continuing

Education

Services

Mold Susceptibility

Building

Material

Susceptible to

mold growth?

Provides food

source for mold?

Deterioration

from mold?

Concrete Masonry Yes No No

Gypsum Wallboard Yes Yes Yes

Wood surfaces Yes Yes Yes

Vinyl, linoleum Yes No (except for

adhesisves)

Yes

Plastics, metals Yes No No

Continuing

Education

Services

Mold Remediation

Building

Material

Remediation Methods

Concrete Masonry Wet vacuum or HEPA vacuum

Gypsum Wallboard Remove and discard if possible, or HEPA vacuum

Wood surfaces Wet vacuum, damp-wipe or scrub surfaces, HEPA

vacuum, or remove and discard if a large area is

affected or if there is significant occupant exposure

during remediation.

Vinyl, linoleum Same as for wood surfaces

Plastics, metals Wet vacuum, damp-wipe or scrub surfaces, or HEPA

vacuum

HEPA = high-efficiency particulate air vacuum

Continuing

Education

Services

Summary

Masonry is a good

choice!

Simply choosing

masonry is not

enough - attention

needed for design,

construction and

maintenance.

NCMA