Commercial Flashing Details

This technical profile illustrates many of the most common flashing details for residential and commercial buildings. The purpose for flashing is to direct moisture to the exterior and in so doing, prevent moisture from deteriorating steel angles or other building components. The following details were designed to accomplish both goals. Modifications to these details are normal, however, the changes should always focus on the primary objectives for flashing. There are some details that vary from standards practiced by the brick industry, however, it is our belief that these variations are a more practical approach.

THE RESPONSIBILITY FOR SPECIFYING THESE ALTERNATIVES BELONGS TO THE DESIGNER OR ENGINEER

General Considerations Pertaining to Flashing Installation

• Whenflashingneedssplicing,theendsshouldbeoverlappedaminimumof4”(100mm)andsealedwithacompatiblemastic.

• Cornerflashingalsorequiressealingoverlappingends.

• Watertightenddamsaresuggestedwherehorizontalflashingterminates.

• Flashinggenerallyshouldextend8”(200mm)abovethebottomoftheflashingandbefastenedtothebackup.

• Throughwallflashingatthebaseofthewallsshouldbelocated2”or3”(50or75mm)abovefinishedgrade.Inthenorthernclimates,thebrickworkshouldbeatleast6”(150mm)abovegrade.

• Anycavityspacebelowtheflashingatthewallbaseshouldbecompletelyfilledwithmortar.

• Whenflashingisplacedoverabrick,block,orconcretewalladjacenttohabitablerooms,athinbedofmortarorcompatiblemasticmustbespreadontothebrick,block,orconcretewallsbeforetheflashingissetinplace.

• Flashingshouldbenoncorrosiveandnonstaining.Copperandgalvanizedsteelmaystainadjacentmasonry.Copperandstainlesssteelrequireaprotectivematerialwhentheyareplacednexttoasteelangle.

• Impregnatedfelt,polyethylene,aluminumorleadshouldnotbeusedasflashing.

Special Considerations Pertaining to FlashingInstallation

Brickindustrystandardsandsomebuildingcodesrequiretheflashingtoproject1/4”(5mm)pastthefaceofthebrick.Thisisthepreferreddetail,butforaestheticreasons,thisissometimesunacceptabletobrickusers.Wherebuildingcodesallow,theflashingcanbeheldback1/2”(12mm),providedtheflashingisplacedonabedofmortar.RefertopaperbyPaulPerlmanonAlternativeFlashingApplicationstoMetalDripEdges(inBrickVeneer).• Forcommercialbuildingswithhorizontalcontrol joints,theflashingmaystopatthebrickfaceor 1/8”(3mm)backfromtheface.Asecondchoiceis toplacetheflashinginthemortarjointabovethe firstbrick,holdtheflashingback1/2Æ\”(12mm) fromthebrickfaceandcovertheshelfanglewitha selfadheringflashing.• Forcommercialandresidentialbuildingswithsills orlintelsoveropenings,theflashingcanstop1/2” to3/4”(12–19mm)backfromthebrickface.Fill thecoreholeswithmortarandspreadsealanton thebrickbelowtheflashingbeforeitisplaced.The linteldetailisillustratedondetail22.Thesilldetailis shownondetail19.

Advantages and Disadvantages of Elastomeric Versus Composite Flashing

Thereareseveralgenerictypesofthrough-wallflashing,specifically,rubber,metal,andcomposite.ThemostcommonlyusedelastomericflashingisEPDM,whichnormallyisacuredproduct,manufacturedin40milthickness.Metalflashingsarecopperorstainlesssteel.Compositeflashingscomeinavarietyofmaterials.Typicallytheyhaveacoppercorematerial,coveredbyasphalt,kraftpaperorpolyethylenefilms.Eachtypehasadvantagesanddisadvantagesasshowninthetablebelow.

Elastomericflashingiseasiertobend,moldandsealatcornersandenddamsthancompositeflashing.Whenflashingneedstospanacrossacavity,compositeflashingismoreeffectivesinceelastomericflashingwillsagandeventuallytearfromsustainedweight.Ifanchorsneedtopenetratetheflashing,athickelastomericflashingwillsealbetteraroundtheanchorthancompositeflashing.

Therearepotentialproblemswiththecompatibilitybetweentheflashingthatextendstothefaceofthebrickandthesealantthatsealsthespacebetweentheundersideoftheflashingandthetopofthebrick.Thisnotereferstodetail26&27.

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Commercial Flashing Details

Theseconddetail,above,alsoshowsahorizontalcontroljoint,butthethrough-wallflashingiscompositeflashing.Fewsealantsadhereeffectivelytobitumencoatedflashing.Iftheflashinghaskraftpaperorpolyethylenefilm,thesecoatingsmaydelaminate.Inordertoovercometheseproblems,abentmetaldripedge,12oz.copperorstainlesssteel,isinstalledunderthecompositeflashingsothatthesealantatthebrickfacewillhavecompatiblesurfacetoadhereto.Inaddition,themetaldripedgecannotsitdirectlyontheshelfangle;otherwise,oneofthemetalsmaycorrode.Therefore,anadditionalpieceofeitherrubberorcompositeflashing,aseparator,isneededbetweenthemetaldripedgeandtheshelfangle.ThemetaldripedgecanalsobeusedwiththeEPDMthroughwallflashing.

ThetablebelowshowsalternativesealantsthathavebeentestedforcompatibilitywithdifferentEPDMflashingmaterials.

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ADVANTAGES DISADVANTAGES

EPDM a.Flexibleb.Easilyspliced

a.Notasstrongasmetalor

compositeflashingb.Compatibilityof

sealantandflashingneedsto

beverified

Metal a.Strongb.Canspanthe

cavitywith-outsupport

c.Compatiblewithmostsealants

a.Expensiveb.Hardtosplicec.Maycorrode

whenincontactwiththeshelfangle

Composite a.Strongb.Canspanthe

cavitywith-outsupport

a.Expensiveb.Theasphalt-

coatedflashingsarenot

compatiblewithmostsealants

c.Coatingsmaydelaminatefromthecore

ThefollowingdrawingsshowtwopossibleflashingdetailsusingEPDMandthecompositeflashing.Thefirstdetail,below,showsahorizontalcontroljointusingEPDMflashingmaterial.Theangleisinstalledwiththeverticallegdownsothattheflashingcannottearontheanchorboltnut.Thisdetailcouldalsoworkwithmetal,copperorstainlesssteelflashing,providedthatthereisarubberorcompositematerialseparatingthemetalflashingfromthesteelangle,similartothenextdetail.Thisflashingdetailcouldbeusedwithalinteljustasitisusedwiththeshelfangle.

Commercial Flashing Details

ThetablebelowshowsalternativesealantsthathavebeentestedforcompatibilitywithdifferentEPDMflashingmaterials.

Whenthecompositeflashingsitsonthemetaldripedge,nosealantisneededbetweenthetwomaterials.WhenEPDMsitsonthemetaldripedge;Carlislerecommends“SecureTape”,Firestonerecommends“FlashguardAdhesiveTape”.

ThesealantslistedfortheEPDMflashingwilladheretothedripedgeandthebrick.However,sealantsadheredifferentlytodifferentabsorptionratebrick,therefore,thebrickadhesionshouldbefield-testedasdescribedbelow.

InadditionEPDMflashingwithprimersappliedmayrequireadhesiontestingtoverifythecompatibilityofthesealantandtheprimer.

Whateversealantsareusedforthehorizontal,orverticalcontroljoints,itisimportantthatactualfield-testingofthesealantsadhesiontotheflashingandtothebrickbedone.

Asimplehandpulltestcanbeusedatthejobsiteafterthesealantisfullycured(usuallywithin7to21days).Itissuggestedthat10testsforthefirst1,000feet(300m)andonetestperthousandfeet(300m)thereafteroronetestperfloorperelevationbeperformed.Thehandpulltestprocedureisasfollows:

1.Makeaknifecuthorizontallyfromonesideofthejointtotheother.

2.Maketwoverticalcuts(fromthehorizontalcut)approximately3”(75mm)long,atbothsidesofthejoint.

3.Placea1”(25mm)markonthesealanttabasshownintheillustrationbelow.

4.Graspthe2”(50mm)pieceofsealantfirmlyjust

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beyondthe1”(25mm)markandpullata90°angle. Ifthesealantitselftears,thentheadhesiontothe

flashingisadequate.5.Ifdissimilarsubstratesarebeingsealed,checkthe

adhesionofsealanttoeachsubstrateseparately.Thisisaccomplishedbyextendingtheverticalcutalongonesideofthejoint,checkingadhesiontotheoppositeside,andthenrepeatingfortheothersurface.

6.Checkwithsealantmanufacturerforsuggested allowableextensions.

Exterior Corner Flashing Detail - Steel & Concrete Columns - Block Backup

Note:Brickanchors&insulationhavebeenomittedforclarity.

EPDM

Sealant CarlislePre-Kleened

FirestoneFlashGuard

Pecora#895Silicone

NoPrimerNecessary

P-120Primer

DowCorning#790Silicone*

NoPrimerNecessary

NoPrimerNecessary

*Doesnoteffectivelyadheretocopper.

Detail1

Detail2

Commercial Flashing Details

Exterior Corner Flashing Detail - Steel Columns - Block Backup

Note:Thisdetailisanalternatetodetail1.Brickanchors&insulationhavebeenomittedforclarity.

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Detail3

Detail4

EnlargedDetailofFlashingAttachmentatColumnBase

Note:Samedetailisusedforintermediatecolumn.

Interior Corner Flashing Detail - Steel & Concrete Columns - Block Backup

Note:Brickanchors&insulationhavebeenomittedforclarity.

Detail5

Detail6

Commercial Flashing Details

Intermediate Column Flashing Detail - Steel & Concrete Columns - Block Backup

Note:Brickanchors&insulationhavebeenomittedforclarity.

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Detail7

Detail8

Note:Supportforthebrickmaybeasteelangleinsteadofaconcretefooting.Supportfortheconcreteblockmaybeaconcreteslabonmetaldeckingsupportedbyasteelbeam.

Exterior Corner Flashing Detail – Steel & Concrete Columns – Metal Studs

Detail9

Detail10

Note:Supportforthebrickmaybeasteelangleinsteadofaconcretefooting.

Commercial Flashing Details

Interior Corner Flashing Detail – Steel & Concrete Columns – Metal Studs

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Detail11

Intermediate Column Flashing Detail – Steel & Concrete Columns – Metal Studs

Note:Bothdetailshavebrickanchors&insulationomittedforclarity.Supportforthebrickmaybeasteelangleinsteadofaconcretefooting.Avoidsupportingsteelanglefrommetalstuds.

Detail13

Detail12

Detail14

Commercial Flashing Details

Typical Flashing DetailsBrick Veneer on Steel Studs

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Detail15–WindowHeadw/LooseAngle

Typical Flashing DetailsBrick Veneer on Concrete Block

Detail18–WindowHeadw/LooseAngle

Detail17–BaseofWall Detail20–BaseofWall

Detail16–WindowSill,OpeningLessThan4ft. Detail19–WindowSill

Commercial Flashing Details

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Detail21–SillDetailW/BrickWindowJambs

Detail22–EnlargedFlashingDetailatLintel

Note:Sealantgoesaroundthebearingendoftheangleandprovidesaprotectivebarrierfrommoisture.

Detail23–EndDams

Note:Thisdetailmayoccuratwindows,doors,andwhereshelfanglestopsatverticalcontroljoints.

Commercial Flashing Details

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Detail24–ShelfAngle

Note:Brickworksupportedonshelfanglepositionedbelowsupportbeam.Supportbeamcouldbeconcrete.Blockbackupcouldbemetalstuds.Anchorsomittedforclarity.

Detail25–AlternateShelfAngle

Note:Anchorsomittedforclarity.

Detail27–AlternatetoDetail26

Note:Refertonoteon“compatibilitybetweenflashingandsealant.”

CopingDetails,seenextpage.

Detail26–EnlargedViewofShelfAngle

Commercial Flashing Details

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Coping Details

Detail29–CornerFlashing

Detail30–MetalCoping

Note:Thissamedetailmaybeusedwithmetalstudsasbackupinsteadofconcreteblock.

Detail28–StoneCoping

Note:Dowelwhichpenetratesflashingmustbesealed.Flashingattopofwallatcornersmustbelappedandsealedsimilartodetail29.Mortarcanreplacebackerrod&sealantontopofbrickprovidedbrickissupportedbyashelfangleattachedtobuildingframeattheroofline.Flashingcoveringcavityshouldbecomposite/metal.

Detail31–GardenWallCoping

Note:Itisconservativetoprovideverticalcontroljointsatapproximately20’–0”to25’–0”(6to8m).Ifflashingisinstalled,cornersrequiretheflashingtobelapped.Northernclimatesshouldhaveoverhangingdrip.

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