control of air leakage in concrete masonry walls tek 6-14a

A n i n f o r m a t i o n s e r i e s f r o m t h e n a t i o n a l a u t h o r i t y o n c o n c r e t e m a s o n r y t e c h n o l o g y

NCMA TEK 6-14A 1

CONTROL OF AIR LEAKAGE INCONCRETE MASONRY WALLS

TEK 6-14AEnergy & IAQ (2011)

INTRODUCTION

Energyefficiencyinbuildingshasbecomeincreasinglyimportant.Whethercomplyingwithnewerenergycodesorgainingrecognitionforsustainablebuildingpractices,reduc-ing theoverall energyusage innewandexistingbuildingscontinuestobealeadingconsiderationfordesignteams. Manymethodsareemployedtoincreasebuildingenergyefficiency.Oneconsiderationisreducingairleakagethroughthebuildingenvelope.Inadditiontothenegativeimpactonabuilding'senergyefficiency(duetothelossofconditionedairviaexfiltrationand/ortheintroductionofunconditionedairviainfiltration),airleakageinbuildingscanalsoimpactmoisturecontrol,indoorairquality,acousticsandoccupantcomfort. Reducedairleakageisoneareawheremasonrywallsexcelcomparedtootherwalltypeswhenproperdesigncriteriaareapplied.ThisTEKreviewsavailableinformationonmasonrywallairleakage,reviewsthemostrecentcodecriteria,presentsconcretemasonrywallassembliesthatmeetthiscriteria,andprovides general guidance on improving the control of airleakageinmasonrywalls.

AIR LEAKAGE

Airleakageconsistsofairinfiltrationfromtheexteriorintotheconditionedspacesofbuildingsand/orexfiltrationofconditionedinteriorairoutofbuildings.Althoughunderapres-suredifferentialaircanpassdirectlythroughmanymaterials,airleakageoccursprimarilythroughamyriadofcracks,gaps,improperlydesignedorconstructedjoints,utilitypenetrations,junctionsbetweenwallandwindowanddoorframes,junctionsbetweenwallandroofassemblies,andotheravenues. Historically,airleakagehasbeentheprimarysourceofbuildingventilation.Becauseitisuncontrolledandweather-

Related TEK:6-11,6-17A

Keywords: airinfiltration,airleakage,coatings,energyconservation,indoorairquality,integralwaterrepellent

dependent,however,thedirectresultofairleakageisanin-creaseofenergyconsumptiontomaintainspaceconditioning.Recognitionofthisincreasedenergyconsumptionhascausedairleakagetoberegulatedbycodeformanynewercommercialbuildings. Reducingairleakagerates,however,canposepotentiallyadversehealtheffectsduetostaleandpollutedairbyreduc-ing theair exchanges thatdilute contaminants.Mechanicalventilationsystemsareusuallyrequiredtosatisfyairexchangerequirementsthathavehistoricallybeenmetbyuncontrolledairleakage.Althoughthereisanaddedcostwithadesignedmechanicalventilationsystem,itistheoreticallyoffsetbytheenergysavingsassociatedwiththereducedairleakage.Heatrecoveryorenergyrecoveryunits(HRV/ERV)canbeusedtoreducetheamountofspaceconditioningrequiredtocondi-tionthefreshair.Thesesystemsshouldbedesignedcarefully,however,assomeresearchshowsthattheenergyconsumedbyoperatingtheHRV/ERVsystemscouldexceedthecostofconditioningthefreshair(ref.1). Studieshaveshownthatairleakageinbuildingscanbedifficulttoaccuratelypredictandmeasure(ref.2).PredictionandmeasurementofairleakageratesinwallshasbeenthesubjectofstudybybothU.S.and international research-ers.U.S.resultshavefocusedprimarilyonthewoodstudwallconstructionwithfibrousinsulationcommontohomebuilding. International research has looked at masonrywallsaswellaswoodframewalls,becausemasonryisthetraditionalEuropeanconstructionmethod.

AIR LEAKAGE LOCATIONS

Akeyissuewhenaddressingairleakageisthesignificantdifference between air leakage at discreet sites, such as atmemberjunctionsandatdoorandwindowopeningswhere

2 NCMA TEK 6-14A

caulkingandsealingisatissue,versusthediffuseairleakagethatcanoccurdirectlythroughawallassembly.Chapter16of theASHRAE Fundamentals Handbook (ref. 3) includestheresultsofresidentialairleakagestudiesthatshowthatthelargestsourceofairleakageoccursthroughwallcracks,jointsandutilitypenetrations.Othermajorleakagesourcesincludeleakagearounddoorsandwindows,ceilingpenetrationsandutilitypenetrations to theattic,and theHVACsystem.Thesame studies showed that diffusion throughwallswas lessthan1%;i.e.,comparedtoinfiltrationthroughholesandotheropenings,diffusionthroughwallswasnotanimportantflowmechanisminresidentialbuildings.ThesedataareillustratedinFigure1.

AIR LEAKAGE CRITERIA

Toreduceairleakagerates,airbarriersystemsaresome-timesdesignedandinstalledaspartofthebuildingenvelope.Alternatively, the thermal envelope can be designed anddetailedtoperformasanairbarriersystem.Currentbuildingcodes(ref.4)donotstipulatequantitativerequirementsforairbarriers,butinsteadrequirethattheexteriorenvelopebesealedtominimizetheinfiltration/exfiltrationofairthroughbothcommercialandresidentialbuildingenvelopes. The2012International Energy Conservation Code(IECC)(ref.5)andsomelocaljurisdictions,however,haveadoptedperformance requirements for the control of air leakage incommercialbuildings.The2012IECCprovidesthreelevelsofcompliance,applyingtoairbarriermaterials,airbarrieras-semblies,orthewholebuilding.ThesecommercialairbarriercriteriaapplyonlytobuildingsinClimateZones4through8.Thecompliancecriteriaare(onlyoneofthesecriterianeedtobesatisfied):• abuildingmaterialintendedtoserveasanairbarriermust

haveanairpermeanceoflessthan0.004cfm/ft2atapres-suredifferentialof1.57lb/ft2(0.02L/s-m2at75Pa),

• anassemblyofmaterialsintendedtoserveasanairbarrier,suchasaconcretemasonrywallassembly,musthaveanairleakagerateoflessthan0.04cfm/ft2atapressuredif-ferentialof1.57lb/ft2(0.2L/s-m2at75Pa),or

• abuildingmusthaveanairleakagerateoflessthan0.4cfm/ft2atapressuredifferentialof1.57lb/ft2(2.0L/s-m2 at75Pa).

Alsocontainedwithinthecodeareseveral"deemed-to-comply"materialsandassemblies.Thefollowingmasonry-relatedmaterialsandassembliesareincludedinthislistandarethereforeconsideredtocomplywiththecode:• fullygroutedconcretemasonry(althoughlistedasamate-rial,thiscomplianceoptionismoreaccuratelydeemedanassembly),

• asamaterial,portlandcement/sandpargeorgypsumplasterwithaminimumthicknessof5/8in.(16mm),

• asanassembly,portlandcement/sandparge,stuccoorplasterwithaminimumthicknessof1/2in.(13mm),and

• concretemasonrywallscoatedwithoneapplicationofblock

fillerandtwoapplicationsofapaintorsealercoating. Thelastoptionisjustifiedbasedonresearchcompletedin the early 2000s.More recent research has documentedadditionaloptionsformaterialsandcoatingstoallowcon-cretemasonryassembliestocomplywiththemaximumas-semblyairleakagerequirementof0.04cfm/ft2atapressuredifferentialof1.57lb/ft2(0.2L/s-m2at75Pa).Althoughnotincludedexplicitlyinthecode,thesetestedassembliescanbeapprovedunderIECCSection102,Alternate Materials,asmeetingtheintentofthecode.ThetestingisdescribedintheMasonry Wall Assembliessectionbelow,andtheresultsaresummarizedintheGuidelinessectiononpage7. The2012IECCalsoliststhefollowingmaterialsasac-ceptableairbarriermaterials(ref.5).Anyoneofthesecanbeused in conjunctionwith concretemasonry constructon, asshowninFigures2and3.• extruded polystyrene insulation boardwith aminimum

thicknessof1/2in.(13mm)withjointssealed,• foil-backedpolyisocyanurateinsulationboardwithamini-

mumthicknessof1/2in.(13mm)withjointssealed,• closed-cellsprayfoaminsulationwithaminimumdensity

of1.5pcf(2.4kg/m3)withaminimumthicknessof11/2in.(36mm),

• open-cellsprayfoaminsulationwithadensitybetween0.4and1.5pcf(0.6-2.4kg/m3)withaminimumthicknessof41/2in.(114mm),and

• gypsumwallboardwithaminimumthicknessof1/2in.(13mm)withjointssealed.

MASONRY WALL ASSEMBLIES

Multi-Wythe Walls Multi-wytheconcretemasonryassemblieshaveavari-etyofoptionsavailableforcompliancewiththecommercialbuildingairleakagerequirementslistedabove.Inadditionto

Figure 1—Typical Residential Air Leakage Sites (ref. 3)

Wall cracks, joints,

penetrations, 35%

Ceiling details,

18%

HVAC system,

18%

Windows and doors, 15%

Fireplaces, 12%

Exhaust vents in conditioned space, 5%

Diffusion through walls,

< 1%

NCMA TEK 6-14A 3

thedeemed-to-complyoptions,therearemanyproprietaryairbarriermaterialsandaccessoriesavailable.Mostairbarriermaterialsaresometypeofcoating,whichisusuallyappliedtothecavitysideofthebackupwythe.Inaddition,sometypesof spray-applied insulation or rigid insulation (with sealedjoints)canbeusedasanairbarrier,asillustratedinFigure2.

Single Wythe Walls Theavailableoptionsforsingle-wytheconcretemasonryassembliesareillustratedinFigure3.Solidgroutingisavail-able,aswellascoatingwithapaint, sealer,orblockfiller.Additionally,exteriorwallcoveringsandinteriorwallfinishesoffersolutions,suchaspargecoating,stucco,plaster,variousinsulationsandgypsumwallboard.Notethatpaints,sealersorblockfillersareeffectivewhenappliedtoeithertheinteriororexteriorsurfaceoftheconcretemasonry.Hence,whenacoatingisspecified,architecturalfinishesneednotbecompromisedbythecoating.

Concrete Masonry Air Leakage Testing ResearchsponsoredbyNCMAandtheNCMAEducationandResearchFoundation(refs.6,7)hasdocumentedadditionalconcretemasonrywallassembliesthatcanmeettheairbarrierassemblyrequirementsof0.04cfm/ft2atapressuredifferentialof1.57lb/ft2(0.2L/s-m2at75Pa).Theresultsaresummarizedbelow.SeeReferences6and7forfulldescriptionsoftheas-sembliesandtestresults.

Commercial-Grade Latex Paint Oneproject(ref.6)testedtheeffectsofcommercial-grade

latexpaintontheairleakagerateofconcretemasonrywallassemblies.Thewallswereungroutedexceptatthefouredges(whichweregroutedsolidtoisolateairpermeancetoa1m2 testsurface).TheresearchemployedamodifiedASTME2178,Standard Test Method for Air Permeance of Building Materi-als(ref.8),becausethereisnostandardizedtestprocedurespecificallysuitedfortestingconcretemasonryassemblies.Threewallsetswerebuiltusingplaingrayconcretemasonryunits,eachwithdifferentconcretemixdesigns,thentestedforairleakage. Thewallsectionswerepaintedwithatypicalcommercial-gradelatexpaint(28%solidscontentbyvolume),thentheairleakageratewasre-measured.Theresearchdocumentedthattheairleakageratedecreasedasthepaintthicknessincreased:itwasdetermined that theair leakage rateof thewallwasinverselyproportionaltothethicknessofthepaintapplied. Whilesurfacetexturewasnotdirectlymeasuredinthisstudy,itisbelievedthatthesurfacetextureofsmooth-facedconcretemasonryunitsaffectstheabilityofthecoatingmate-rialtodevelopacontinuouscoating,whichisimportantforreducingairleakageratesthroughassemblies. Theresultsofthisresearchindicatethattheairleakagerateof12-in.(305-mm)concretemasonrywallscanbereducedto0.04cfm/ft2orlessatapressuredifferentialof1.57lb/ft2(0.20L/s-m2at75Pa)byapplyingbetween3.3and14.6mils(0.084and0.371mm)of commercial-grade latexpaint forconcretemasonryunitswithasmoothtexturedsurfaceandacoarsetexturedsurface,respectively.

High-Quality Latex Paint Morerecentresearch(ref.7)evaluatedtheeffectsoffour

additionalcoatings:ahigh-qualitylatexpaint,ma-sonryblockfiller,waterrepellentsurfacecoatings,andgypsumwallboard.Theconcretemasonryunitsusedinthisstudywerealsoplaingray,medium-weight"utility"typeunitswithafairlyopensurfacetexture(seeFigure4).Theuseofintegralwaterrepellentadmixtureswasalsoinvestigated. The latexpaintused in thisprojectwasahigh-qualityretailpaint,witha28%solidscontentbyvolumeand47%solidscontentbyweight.Toevaluatethispaint,asinglecoatwasappliedwithanaveragedryfilmthicknessof1.28mil(0.033mm).Thepaintreducedtheairleakagerateby94%,toacalculatedaverageair leakagerateof0.011 cfm/ft2 (0.05L/s-m2),well below the as-semblyrequirementof0.04cfm/ft2(0.2L/s-m2). Theresultsindicatethatwhenahighqualitylatexpaintisused,asinglecoatisallthatisneces-sarytocreateacontinuouscoatingandprovidetherequiredbarriertoairflow.

Masonry Block Filler Theblockfillerevaluatedwasawater-basedmasonryprimerdesignedforuseonconcreteand

Figure 2—Masonry Cavity Wall Detail

Caulkorotherwisesealpenetrations

Concretemasonrybackup

Concretemasonryveneer

Airspace,1in.(25mm),min.

Thefollowinginsulationsactasanairbarrier(ref.5):extrudedpolystyreneorfoil-backedpolyisocyanurateinsulationboardwithaminimumthicknessof 1

2in.(13mm)withjointssealed,closed-cellsprayfoaminsulationwithaminimumdensityof1.5pcf(2.4kg/m)withaminimunthicknessof11

2in.(36mm),open-cellsprayfoaminsulationwithadensitybetween0.4and1.5pcf(0.6-2.4kg/m)withaminimunthicknessof41

2in.(114mm)

3

Horizontaljointreinforcementatalternatingcourses

3

Jointreinforcementwitheyeandpintlewallties

4 NCMA TEK 6-14A

Figure 4—Photo Showing Surface Texture of Tested Units (ref. 7)

Figure 3—Air Leakage Compliance Options for Single Wythe Concrete Masonry Walls

Allcellsgrouted

(a)Fullygrouted

Masonrycoatedwith:1coathighqualitylatexpaint,or2coatscommercial- gradelatexpaint,or1coatmasonryblockfille r,orPortlandcement/sandpa rge,stucco,orplaster, 1

2in.(13mm)thick,min

(b)Paintsandcoatings(interiororexterior)

Gypsumwallboard, 12in.

(13mm)thickmin.,withjointssealed

(d)Gypsumwallboard

Extrudedpolystyreneorfoil-backedpolyisocyanurate, 1

2in.(13mm)thick,min.

(e)Exteriorinsulationandfinishsystem

Heavyduty(HD)polyisocyanurate,minimum 1

2in.(13mm)thick,withjointssealed

(c)HDpolyisocyanurateappliedtointerior

concretemasonry surfaces. Thismaterial is typicallyusedasabaseprimercoatonconcreteandmasonrysurfaces inpreparationforpainting.Itisathickercoatingmaterialthanlatexpaint,designedtofillporesandsurfaceimperfectionsinmasonrywalls.Basedoninformationprovidedbythemanu-facturer,thismaterialhasa46%solidscontentbyvolumeand55%solidscontentbyweight. Asinglecoatofblockfillerwasappliedwithanaveragedryfilmthicknessof2.10mil(0.053mm).Theairleakageratewas reducedby86%due to thepresenceof theblockfillercoating,to0.011cfm/ft2(0.05L/s-m2).Thisresultiswellbelowtheairbarrierassemblyrequirementof0.04cfm/ft2(0.2L/s-m2).

Gypsum Wallboard A setof assemblieswasalsoevaluated for air leakageafterinstalling½in.(12.7mm)gypsumwallboardtosimulateasingle-wytheassemblywithadrywall-finishedinterior. Whenthegypsumwallboardwastestedbyitself,ithad

NCMA TEK 6-14A 5

anairpermeancebelowtheairbarriermaterialrequirementof0.004cfm/ft2(0.02L/s-m2).Whentheconcretemasonryassemblywastestedwithwallboardattached,itwasevidentthattheperformanceoftheassemblywasdominatedbytheairpermeanceofthewallboard,asverylittleairleakagewasmeasured,andtheresultswerebelowthe0.004cfm/ft2(0.02L/s-m2)requirementforanairbarriermaterial.

Water-Repellent Surface Coatings Becausemanysingle-wytheconcretemasonryassembliesusesometypeofwaterrepellentsurfacecoating,thesecoat-ingsmaybeanefficientwaytoreduceairleakagerates.Bothasilane/siloxaneandanacrylicmicroemulsionwaterrepellentcoatingwereevaluated. Whilebothwaterrepellentcoatingsreducedtheairleak-agerateoftheassemblies,thereductionwasnotsufficienttocomplywiththe2012IECCairbarrierassemblyrequirementsforcommercialbuildings.

Integral Water Repellents Theeffectofanintegralwaterrepellentinconcretema-sonryunitsandmasonrymortarwasalsoevaluated.Integralwaterrepellentsinconcretemasonryunitscanimprovethecompactionoftheunit,leadingtoaslightlytighterconcretematrixand,insomecases,amoreuniformsurfacetexture. Thetestedsetofconcretemasonryassembliescontainedanintegralwaterrepellentadmixtureatanappropriatedosagetoproducewaterrepellentcharacteristics. Comparedtotheassemblieswithoutanintegralwaterrepellent,theadditionofintegralwaterrepellentdecreasedtheairleakagerateby28%onaverage.Thisdecreaseislikely due to a slightly tighter pore structure resultingfromtheuseoftheintegralwaterrepellent.Thedecreaseinleakagerate,however,wasnotsufficienttoreducetheassemblyairleakageratetolevelsthatcomplywiththe2012IECC.

CONCRETE MASONRY COMPARED TO FRAME CONSTRUCTION

Typicalmasonryconstructiondoesnotincludesomeof the leakage sites common in framewalls.Masonrywallsdonothavesoleplates(sills),becausethewallisacontinuousassemblyfromthefootingup.Thetopofamasonrywallistypicallyatie-beamorbondbeam.Trussesorraftersaresettoaplateattachedtothetopcourseofmasonry.Qualitycaulkingandsealingareimportantattheceilingfinishedge.Sealingisalsorequiredatatticaccessways,aswellasaroundanywallpenetrations.

Commercial Buildings Measuredairleakageratesfromexistingcommercialbuildings constructed during or after 1980 have beencompiled(ref.9).Fromthisdata,84%ofthemasonrybuildings included had measured whole-building air

leakageratesoflessthan2cfm/ft2at apressuredifferentialof1.57lb/ft2(10L/s-m2at75Pa).Incomparison,only30%offrame-walledbuildingshadmeasuredwholebuildingairleakageratesoflessthan2cfm/ft2at apressuredifferentialof1.57lb/ft2(10L/s-m2at75Pa)(itshouldbenotedthatnoneofthesebuildingswereconstructedtomeetanairtight-nessstandard).Thereportedleakagerateswerenormalizedbytheabove-gradeareaofthebuildingenvelope.Thedatawere compiled from various references, and represent arangeofclimatesandbuildingtypes,makingitdifficulttodrawdefiniteconclusions.Theresultsdoindicate,however,thatexistingmasonrybuildingstendtohavemuchlowerairleakageratesthanexistingframe-walledbuildings.

Residential Buildings Theair leakageratesofmasonrywallshavealsobeenresearchedwidelyinEuropebysuchgroupsastheAirVen-tilationandInfiltrationCenterinEngland(ref.10).Resultsfromdetailedair leakageworkperformed inFinland showthatconcretemasonryand lightweightconcrete(panelized)walledhomeshadmuch lowerair leakagerates thanwoodframestructures(ref.11).Figure5illustratesthesedifferences,comparingolderwoodframehousesaveraging7.3airchangesperhour(ACH)at50Patomoremodernsite-builtwoodframehousesaveraging8.5ACH,withaverywiderangeofvalues.Prefabricatedwoodelement (panelized)houseswerebetter

Figure 5—Leakage Factors at 50 Pa for Detached Houses (ref. 11)

1

5

2 3

Leakage factor n (UN)50

Structure type

Variation range

10

15

20

54

10.4

6.0

7.38.5

2.9

17.8

12.0

2.2

6.0

3.5

2.3

5.34.5

1.8

3.0

Key: 1.Older wooden houses, sawdust insulation.*2.New wooden houses, bulk on site.*3.Prefabricated wood element houses.*4.Concrete element houses. 5.Lightweight concrete houses.* With mineral wood insulation

Key:1.Olderwoodhouses,sawdustinsulation.2.Newwoodhouses,builtonsite.*3.Prefabricatedwoodelementhouses.*4.Concretemasonryhouses.*5.Lightweightconcretehouses.*withmineralwoolinsulation

Airchangesperhour

6 NCMA TEK 6-14A

at6.0ACH.Bothconcretemasonryandlightweightconcretehouses,however,hadroughlyone-halftheairchangerateoftheaveragepanelizedwoodframehomes. Propersealingofcomponentsintomasonryroughopen-ingsmaybemoreimportantthanreducingairleakagethroughmasonryassemblies.Dr.HiroshiYoshinoofJapan'sTohokuUniversityinvestigatedJapanesehousingairleakage(ref.12)inabroadcomparisonwithdatafromothernations.Herankeddata points from his own research and other investigatorsintoairtightnesscategories.Heobservedthatsomeconcretemulti-familyhousingwassoairtightthatindoorairqualityandcondensationproblemsresulted,andventilationwasrequired.Concretemasonryhousesof"air-tight"constructionrankedamongthebestinJapanforairtightness.SeveraloftheotherJapanesereportshecitedalsoshowedconcreteandconcretemasonryhousestohavelowerairleakageratesthantypicalJapaneseframehouses. Belgianresearchersusedasequentialtechniqueinma-sonryhomestoexamineincrementalairleakagemeasures(ref.14).Figure6showstheprogressionofairchangeratesat50Pafrom"normalconstruction,"whichevidentlyassumesnoairleakagereductionmeasures,toamasonrywallwithallwindows,doorsandpenetrationssealedandweatherstripped.Sealingjusttheseitemsresultedinabout87%lessairleakage.Thelargestimprovementsareseenaftersealingthedoorandwindow frames to their respective roughopenings,whichagreeswiththedatainASHRAE(ref.3).TheBelgianfindingsalsoagreewithastatementinacompendiumofEuropeanairleakageresultswhichstates:“Thecriticaldetailsfromthe

pointofviewofair-tightnessareassociatedwiththe(qualityof)formationofopeningsinmasonrywalls…"(ref.14).

IMPACTS ON MOISTURE Whenanairbarriermaterialisrequired,itsplacementcanbecriticaltocontrollingmoistureandhencetowalldurability.First,becauseairmovementcancarryasignificantamountofmoistureintoorthroughabuildingassembly,andsecondbecausetheairbarriercanactasavaporretarder.Notethatanairbarrierisdesignedtocontrolthemovementofairbothintoandoutofthebuildingenvelope,whereasavaporretarderisdesignedtorestrictthediffusionofwatervaporthroughbuildingmaterialsandsubsequentcondensation.Becauseavaporretardercanalsoinhibitdrying,theneedforavaporretardervarieswithclimate,constructiontypeandbuildinguse. Althoughthefunctionsofairbarriersandvaporretardersdiffer,insomecasesonecomponentcanservebothneeds.Indesignswhereonematerialisinstalledtocontrolbothairandwatervapormovement,itisimportantthatthematerialiscontinuoustoprovidetherequiredlevelofairtightness.Where separate airflow and vapor retarders are installed,caremustbetakentoensurethattheairbarriercannotcausemoisturecondensation.Thiscanbeaccomplished throughthechoiceofvapor-permeablematerialsorthroughproperplacement. MoredetailedinformationonvaporretardersinconcretemasonrywallscanbefoundinTEK6-17A,Condensation Control in Concrete Masonry Walls(ref.13).

DISCUSSION

Airleakagemeasurementsindicatethatprop-erlyconstructedconcretemasonrywallsmayhavebetternaturalresistancetoairleakagethantypicalframeconstruction.Ifafurtherreductioninairleak-ageratesisrequired,variousoptionsareavailable.Retrofitsforreducingairleakageinconcretemasonryconstructionarestraightforward,becausefewerdis-similarjointsareinvolved.Alsostucco,paintsandmasticstendtobelessexpensivethannewsheathing,polymerpapers,etc.

GUIDELINES

Thefollowingconcretemasonrywallassembliesareconsideredtomeetanairleakageoflessthan0.04cfm/ft2(0.20L/s-m2)at75Pa,either by prescriptive code requirements or asdemonstratedthroughlaboratorytesting.ByprescriptiveIECCcriteria(ref.5):• Fullygroutedconcretemasonry.• Concretemasonrywithaportlandcement/

Figure 6—Incremental Improvements in Air Leakage in a Masonry Home, Field Results (ref. 14)

0 500

50

100 150

100

150

200

Air infiltation m /h3

Pressure difference (Pa)

1

23

4

5

1. Normal construction.2. As 1. but with door also

sealed.3. As 2. but with

electricity entry point sealed.

4. As 3. but with the window-front masonry joint also sealed.

5. As 4. but with opening window joints weatherstripped.

1.Normalconstruction.2.As1,butwithdoor

alsosealed.3.As2,butwith electricityentrypoint

sealed.4.As3,butwiththe

window-front masonryjointalso

sealed.5. As4,butwith openingwindow

jointsweather-stripped.

Pressuredifference(Pa)

NCMA TEK 6-14A 7

sand parge, stucco or plaster with aminimumthicknessof1/2in.(13mm).

• Concretemasonrywallscoatedwithoneapplicationofblockfiller and twoapplicationsof apaintorsealercoating.

Bylaboratorytesting(refs.6,8):• 12-in.(305-mm)concretemasonrysealedwithat least

two coats of commercial-grade latexpaint.

• 8-in. (203-mm)concretemasonrycoatedwithasinglecoatofhigh-qualitylatexpaint.

• 8-in. (203-mm)concretemasonrycoatedwithasinglecoatofmasonryblockfiller.

Itcanbereasonablyassumedthatcompliancewouldalsobeachievedbyapplying thesecoatings towallshavingalargerthicknessthanthosetested. Whencoatingssuchaspaintorblockfillerarecalledfor,theycanbeappliedtoeithertheinteriororexteriorsideoftheconcretemasonry,soanymasonryarchitecturalfinishesneednotbecompromised.

8 NCMA TEK 6-14A

NCMA and the companies disseminating this technical information disclaim any and all responsibility and liability for the accuracy and the application of the information contained in this publication.

NATIONAL CONCRETE MASONRY ASSOCIATION13750SunriseValleyDrive,Herndon,Virginia20171

www.ncma.org

ToorderacompleteTEKManualorTEKIndex,contactNCMAPublications(703)713-1900

REFERENCES1. Sherman,MaxH.andIainS.Walker,LBNL62341.Energy Impact of Residential Ventilation Norms in the United States,

LawrenceBerkeleyNationalLaboratory,2007.2. Carr,D.andJ.Keyes,Component Leakage Values and their Relationship to Air Infiltration,StevenWinterAssociates,1984.3. 2009 ASHRAE Handbook - Fundamentals.AmericanSocietyofHeating,RefrigeratingandAir-ConditioningEngineers,Inc.,

2009.4. International Energy Conservation Code.InternationalCodeCouncil,2006and2009.5. International Energy Conservation Code.InternationalCodeCouncil,2012.6. Biggs,DavidT.,Air Permeance Testing of Concrete Masonry Wall Assemblies,FR06.NationalConcreteMasonryResearch

andDevelopmentLaboratory,January2008.7. Assessment of the Effectiveness of Water Repellents and Other Surface Coatings on Reducing the Air Permeance of Single

Wythe Concrete Masonry Assemblies,MR36.NationalConcreteMasonryAssociation,2010.8. Standard Test Method for Air Permeance of Building Materials,E2178-03.ASTMInternational,2003.9. EmmerlichS.J.,T.McDowell,W.Anis,Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC

Energy Use,NISTIR7238.NationalInstituteofStandardsandTechnology,2005.10. AirVentilationandInfiltrationCenter,OldBracknellLaneWest,Bracknell,Berkshire,RG124AH,GreatBritain.11. Kohonen,R.,S.AhvenainenandP.Saarnio.Review of Air Infiltration Research in Finland,AirInfiltrationReviewVol.6,No.

1,1984.12. Yoshiro,Dr.H.Overview of Air Infiltration in Japan,AirInfiltrationReview.Vol.5No.3,May1984.13. Condensation Control in Concrete Masonry Walls,TEK6-17A.NationalConcreteMasonryAssociation,2000.14. Caluwaerts,P.andP.Nusgens.Overview of Research Work in Air Infiltration and Related Areas in Belgium,AirInfiltration

Review.Vol.5No.1,1983.