Maintenance and InspectionManual for Precast Concrete

Building Enclosures

CANADIAN PRECAST/PRESTRESSED CONCRETE INSTITUTECANADIAN PRECAST/PRESTRESSED CONCRETE INSTITUTE

REV. JANUARY 2020

John Straube, Ph.D., P.Eng.rdh.com

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AboutCPCI

TheCanadianPrecast/PrestressedConcreteInstitute(CPCI)isthebodyofknowledgefortheprecastconcreteindustryinCanada.CPCIrepresents37manufacturingmemberswithatotalof57plants,alongwithassociate,professionalandstudentmembersthroughoutCanada.TheCPCImanufacturingmembershaveover350,000sq.mofplantspaceavailableforproducingtheprecastconcreteyourequireforyourproject.Theinherentbenefitsofprecastprestressedconcretemakeitthebestchoiceformanyprojects.Fastproduction,deliveryanderectionsavestimeandmoney.Thecreativedimensionsofshape,texture,colourandpatternproduceattractivebuildings.Qualityanddurabilitymeansunsurpassedlowmaintenanceandlife-timecosteffectiveness.

CPCIMembershavethefacilities,thepeople,theproductsandthedesiretomakeameaningfulcontributiontotheplanning,completionandsustainabilityofyournextproject.

Prepared by: RDH Building Science Inc.

167 Lexington Court, Unit 5 Waterloo, Ontario Canada N2J 4R9

Primary Author: John Straube, Ph.D., P.Eng.

DISCLAIMER: Substantial effort has been made to ensure that all data and information in this publication is accurate. RDH Building Science Inc. and the Canadian Precast/Prestressed Concrete Institute cannot accept responsibility of any errors or oversights in the use of material or in the preparation of architectural or engineering plans. The design professional must recognize that no design guide can substitute for experienced engineering and professional judgment. This publication is intended for use by professional personnel competent to evaluate the significance and limitations of its contents and able to accept responsibility for the application of the material it contains. Users are encouraged to offer comments to RDH Building Science Inc. on the content and suggestions for improvement. Questions concerning the source and derivation of any material in the design guide should be directed to RDH Building Science Inc.

AboutthisManual

TheCanadianPrecast/PrestressedConcreteInstitute(CPCI)preparedthismanualtoassistbuildingownersandmaintenancestaffinplanningthemaintenanceofprecastconcretecladdingonbuildings.Periodicmaintenancewillallowtheprecastsystemtoperformasdesignedandextendtheservicelifeoftheprecastconcreteenclosure.Therecommendationsandproceduresincludedinthismanualwillalsoserveasaresourceforarchitects,engineers,andservicecontractorsinvolvedintheperiodicrepairandrenewalofprecastconcreteenclosuresystemcomponents.Theinformationprovidedoncommonfailuresandrepairmethodologyshouldalsoallowthedesignersofnewprecastenclosurestoavoidthesepitfalls.

Thefirstsectionoftheguideintroducesfunctionalrequirementsofthebuildingenclosureinitsmainroleasanenvironmentalseparator.Includedinthisisadiscussionofthedifferentcommonprecastenclosuretechnologieswhichwillserveasanidentificationguideforbuildingownersandoperators.

Thesecondsectionidentifiesthemaintenancerequirementsofthecommontypeofprecastenclosuresystemsandsuggestedproceduresforinspection.Photographsanddrawingsofthesystemsandpotentialmaintenanceissuesareprovidedasavisualreferenceforinspections.Beyonddescriptionsofdamagethatmayleadtoprematuredegradationoftheconcretepanelorpanelattachments,themanualdoesnotincludeinformationontheassessmentofthestructuralintegrityoftheprecastelementsandmainbuildingstructure.Forstructuralinspections,theownerisadvisedtoretaintheservicesofalicensedstructuralengineerexperiencedinthedesignandconstructionofprecastconcretesystems.

Thethirdsectionpresentsexampleinspectionandmaintenancecheckliststhatcanformthebasicmaintenancedocumentationforaprecastconcreteenclosure.

Inthefinalsectionoftheguide,acollectionofresourcesonmorespecifictopicsandthecontactinformationfortheCPCITechnicalSupporthelpdeskhasbeenincluded.

Contents1.0Introduction 4Whateverygoodbuildingenclosureshoulddo 4Identificationofcommontypesofprecastfacades 6

2.0InspectionandMaintenanceRequirements 13WhatKindofMaintenanceisRequired? 13GeneralMaintenanceandInspectionRequirementsforPrecastEnclosures 14RequiredInspectionandMaintenanceByComponent 17

3.0PlanningandDocumentation 28SampleInspectionandMaintenancePlanforExteriorPrecastEnclosures 29ExamplePrecastEnclosureInspectionChecklist–byComponent 31

4.0ResourcesandReferences 37

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1.0IntroductionPrecastconcreteprovidesmanyadvantagesoverothersystemswhichmakeprecastbuildingenclosuresdurable,long-lastingsystemswithlowmaintenancerequirementsbothoutsideandinsidethebuilding.

Concreteoffersexcellentresistancetoweatheringandcorrosioninmostclimates.High-density,largeformatprecastconcretepanelsare,bythemselves,resistanttoairandwaterpenetration.Providedthatpaneljointsarewell-designedandproperlymaintained,thesystem,asawhole,offersexcellentprotectionfromclimaticconditions.

Inbuildingswherethepanelsareusedastheinteriorfinish,aprecastconcretewallpaneloffersasmooth,densesurfacethatmaybeeasilycleanedtherebyminimizingthecollectionofdirtandcontaminants.Precastconcretealsodoesnotimpacttheoccupants’indoorairqualityasitdoesnotoff-gas.

Nevertheless,giventheenvironmentalexposurethatallbuildingsmustendure,allenclosuresystemsrequiresomemaintenanceactivityovertime.Thismanualexaminestheexpectedmaintenancerequirementsthatarespecifictoprecastconcreteenclosuresystems.Thefollowingsectionexplainshowtypicalprecastconcreteenclosuresaredesignedtofunctionsothatthatallreadershaveacommonbackgroundwhenreviewingthemaintenancerequirementsfortheirbuilding.

WhatEveryGoodBuildingEnclosureShouldDo

Thefollowingsectionsetsoutthepurposeandfunctionofthebuildingenclosuretoensurethattheroleofallcomponentsiswellunderstood.Thisinformationisimportantforplanningmaintenanceactivitiesbutcriticalwhenmakingplansformajorrepairorrenewalofbuildingenclosurecomponents.

Thebuildingenclosureisdefinedasthephysicalcomponentofabuildingthatseparatestheinteriorenvironmentfromtheexteriorenvironment:itisanenvironmentalseparator.Inpractice,thebuildingenclosurehastoprovidethe“skin”tothebuilding,i.e.,notjusttheenvironmentalseparationbutalsothevisiblefacade.

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Unlikethesuperstructureortheservicesystemsofbuildings,theenclosureisnearlyalwaysvisible,andthereforeofcriticalimportancetoowners,occupants,andthepublic.Theappearanceandoperationoftheenclosurehasamajorinfluenceontheinteriorenvironmentandonfactorssuchascomfort,energyefficiency,durability,andoccupantproductivity,satisfactionandhealth.

Ingeneral,thephysicalfunctionofenvironmentalseparationcanbefurthergroupedintothreeusefulsub-categoriesasfollows:

1. Support,i.e.,tosupport,resist,transferandotherwiseaccommodateallstructuralloadingimposedbytheinteriorandexteriorenvironments,bytheenclosure,andbythebuildingitself.Theenclosure,orportionsofit,cansometimesbeanintegralpartofthebuildingsuperstructureeitherbydesignorinactualperformance.

2. Control,i.e.,tocontrol,block,regulateand/ormoderatealltheenvironmentalloadingsduetotheseparationoftheinteriorandexteriorenvironments.Thislargelymeanstheflowofmass(rain,air,watervapor,pollutants,etc.)andenergy(heat,sound,fire,light,etc.).

3. Finish,i.e.,tofinishthesurfacesattheinterfaceoftheenclosurewiththeinteriorandexteriorenvironments.Eachofthetwointerfacesmustmeettherelevantvisual,aesthetic,durabilityandotherperformancerequirements.

Allpracticalenclosuresmustsatisfythesupport,control,andfinishfunctions;however,onlythesupportandcontrolfunctionsareneededeverywhere.Controlandsupportfunctionsmustcontinueacrosseverypenetration,everyinterfaceandeveryassembly.Thelackofthiscontinuityisthecauseofthevastmajorityofenclosureperformanceproblems.Theneedforfinishvaries-itisunlikelytofindanenclosurethatrequiresafinishontheinteriorandexterioreverywhereandthisistrueformanyprecastenclosureswheresomecomponentssuchassecondarysealsandstructuralconnectionsarehiddenbehindotherfinishmaterials.

Thesupportfunctionisofprimaryimportance.Withoutstructuralintegrity,theremainingfunctionsareofnouse.Theprecastindustryhasreachedahighlevelofunderstandingandaccomplishmentinthisarea.

Forphysicalperformance,themostcommonrequiredenclosurecontrolfunctionsincluderesistanceto:rainpenetration,airflow,heattransfer,condensation,fire&smokepropagation,soundandlighttransmission(includingview,solarheat,anddaylight),insectinfestation,particulatepenetration,andhumanaccess.Asthesefunctionsarerequiredeverywhere,continuityofthesecontrolfunctions,especiallyatpenetrations,connectionsandinterfacesbetweenmaterials,iscriticaltoasuccessfulenclosure.Themostimportantcontrolfunctionwithrespecttodurabilityisraincontrolfollowedbyairflowcontrol,thermalcontrol,andvapourcontrol.Theleveloffireandsoundcontrolrequiredvarieswithcoderequirementsandownerrequirements.

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Unlikethecontrolandsupportfunctions,whichrelyoncontinuitytoachieveperformance,thefinishfunctionisoptional,andmaynotbeneededinsomeareas,suchasabovesuspendedceilingsorinserviceorindustrialspaceswherethefinishisoftendeemedunimportant.Exteriorfinishcomponentsareoftentermed“cladding”,butthetermisimprecise,sincecladdingsystemsandmaterialsoftenincludesomecontrolfunctions(suchasUVcontrol,solarcontrol,impactresistance,etc.)whilealsoprovidingthefinishfunction.

Asthemostimportantofthecontrolfunctions,rainpenetrationdeservesspecialattentioninalldesignsandisafocusofthemaintenancerecommendationsprovidedinthefollowingsections.

IdentificationofCommonTypesofPrecastFacades

Whilemostwallassembliesthatrelyonconcreteastheexposedfinishhavesimilarmaintenancerequirements(forexample,cast-in-placeconcrete,tilt-uppanelconstruction,andprecastelements),therearetwomaintypesofprecastfacadesthatarelikelytobeencountered.Thissectiondescribesthedifferencebetween“face-sealed”and“drained”systemsandexplainshoweachsystemhandlesrainwaterpenetrationandairflow,andthedifferentapproachestomaintenanceforeachsystem.

Itshouldbenotedthatmaintenanceorrenewalactivitiesonolderbuildingsmayhaveswitchedallorpartoftheenclosurefromonecontrolapproachtotheother.

Face-sealedFacades

Aface-sealedfacadeisatypeof“perfectbarrier”approachtorainandaircontrol.Controlofrainpenetrationoccursattheexterior“face”ofthesystemusingtheconcretepanelsand(typically)sealantjoints.Inthisapproach,thereisnosecondarylayerofrainorwatercontrolhiddendeeperintheassembly–allimportantelementsarevisibleattheexteriorface.Theface-sealedapproachiscommonforsometypesofglazingandpanelsystemsasillustratedinFigures1and2.

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Figure1:Identification–Inaface-sealedsystem,therewillbenovisibledrainageholesortubesintheexteriorsealantandnovisibleflashingcomponentsbetweenpanels.Thesealantshownontheleftisclearlyfailing.Thephotototherightshowsacceptablesealant.

Figure2:Face-sealedperfectbarrierwalls.

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Precastpanelsarereinforcedforcrackcontrolandtypicallymadeofhigh-qualityconcretewithlowwater-to-cementratiosandverylowwaterabsorption.Itisforthesereasonsthattheycanactasareliablebarriertowaterpenetration.Millionsofsquarefeetofprecastpanelsinstalledoverthelastfivedecadeshaveprovidedthereal-lifeproofofthis.1However,thepolymersealantsbetweenpanelsandbetweenpanelsandothercomponentsaresusceptibletoworkmanshipflawsduringconstructionandslowdeteriorationovertime.

Inmanyolderprecastbuildings,thejointsbetweenpanelsandaroundpenetrations(especiallywindows)andtheinterfaceswithadjacentenclosuresystemsaremostlikelytohavebeenmadewithperfect-barriersealants–asingle,exposedlineofrainandaircontrol.Newerprecastsystemsincorporatedrainedjointsbetweenpanelsandbetweenpanelsandotherenclosureelements.Seediscussionin“DrainedFacades”below.

DrainedFacades

Toaccommodatethejointsbetweenpanels,theconceptofadrainedjoint,ortwo-stagesealhasbeenpromotedforalmost50yearsandwidelyusedwithgreatsuccessforalmostaslong.

Theinteriorairseal/waterseal(drainageplane)canbeinstalledfromtheinteriorortheexterior.Althoughinstallationfromtheinteriorhasbeencommoninthepast,itisoftendifficulttoaccesstheinteriorjointatcolumns,floorslabs,perimeterroofbeams,shearwalls,plateconnections,andotherobstructions.Itisnowrecommendedthattwo-stagejointshavetheinteriorairseal/drainageplaneappliedfromtheexterior(seeFigures3and4)tohelpensurecontinuityofboththeairandwaterseal.

1ChinandGerns(1998)providecasestudiesofprecastconcretefailureinvestigations.Theirexperience,whichmirrorsthatofthisauthorandRDHBuildingScience,isthatwaterdoesnotpenetratethroughtheprecastconcretepanelbutonlythroughjointsandpenetrations.

DefinitionBarrierSystemorPerfectBarrierThegeneraltermtodescribearaincontrolapproachthatreliesontheperfectionofasingleplaneofmaterial(s)toresistrainwaterpenetration.Twosub-types,face-sealedandconcealedbarrier,arecommonlyused.

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Figure3:Identification–AweepholeinaTwo-stageorDrained-Jointsystemallowsfordrainagefromtheinnersealtotheexterior.Notethegoodconditionofthesealantvisible.

Figure4:Three-dimensionalrepresentationofaTwo-StageDrainedJointorientedbothverticallyandhorizontallybetweenprecastpanels.

Analternateapproachtointroducedrainageinsomeprecastwallsystemsistheinclusionofadrainageplanebehindtheprecastpanel.Thisisunnecessary,howeversomedesignershavechosentoignoretheuniquepropertiesofprecastconcrete,anddesignprecastsystemsthatattempttomimicthedrainedscreenraincontrolapproachofbrick,stone,orstuccoveneers.

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Inpractice,itcanbedifficulttoproperlyexecuteafulldrainageplanebehindthick,architecturalprecastpanels.Themanyconnections(perhapsthousandsoveralargebuilding)aredifficulttoaccessandrequirepenetrationsthroughthedrainageplanethatneedtobesealedafterpanelinstallation.Carefulplanningcanhelpbutanydeviationinthesystemofconnectionsrequiresnewpenetrationsandadditionalefforttoensurethedrainageplaneisrestored.Inaddition,theairgapbehindthearchitecturalprecastcancreateapathforinteriorairtoflowlaterally.Astheprecastconcreteisbothanairandvapourbarrier,airfromtheinteriormaybeabletoentertheairgapduringcoldweather.Ifitdoes,theairinthegapwillcool,fall,anddraginairfromtheindoorswhileconnectinganyflawsintheinteriorairtightlayerstogether.Theresultingconvectiveloopthatcanformhasbeenobserved(bytheauthor)tocollectthousandsoflitresofcondensationduringcoldweather.

Itshouldbenotedthatthedrainedscreenapproachcanbeusedinsystemswhichallowafulldrainageplaneandairbarriertobeinstalledoverallsupportingstructureandmadecontinuousbeforetheprecastpanelsareinstalled.Therearesomeinstanceswherethesesystemscanbedesignedandbuiltreliablyasadrainedsystem.Forexample,small“handset”precastpanels,thosewithmanyjointsandsupportedonpre-installedanchors,areoftensuccessfullyandeffectivelybuiltasdrainedsystems(Figure5).Thissystemcanalsobeusedonshearwallsandelevatorshaftswithpocketsprovidedinthecastinplaceconcrete.

DefinitionDrainedScreenAbuildingenclosureraincontrolstrategythatacceptsthatsomewaterwillpenetratetheoutersurface(thecladding,which“screens”rain)anddirectsthiswaterbacktotheexteriorbygravitydrainageoveradrainageplane,throughadrainagegap,andexitingviaflashingandweepholes.AlsocalledRainscreen.

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Figure5:Identification–Adrainedprecastenclosuresystemusingsmall,handsetprecastpanels.Inthissystem,jointsbetweenpanelsaregenerallynotsealedandflashingelementsmaybevisibleatfloorlevelsandaroundwindowopenings.

ANoteonVeneerPanels

Veneerpanelsarecomprisedofaprecastconcretebackuppanelwithaveneermaterial(stone,metal,etc.)attachedtotheface.TheclaybrickveneershowninFigure6isacommonchoice.

Theapproachtorainpenetrationcontrolmayvaryintheveneerpanelsfromaperfectbarrierwithdrainedjoints(morecommonfornewconstruction)andaconcealedperfectbarrierapproach(i.e.,panelsandsinglelineofsealantinsetinthejointbehindtheveneer),whichmaybefoundinolderconstruction.Minorrepairandplannedreplacementofthesealantjointsmayhavechangedtheapproachtorainpenetrationcontrol(insomecasesbysealingintentionaldrainageholes).Insomecases(seeFigure7below)replacementofsealantattheexteriorfaceofthewall(i.e.,attheveneer)andatwindowsinterfacesmaypreventdrainagefrompaneljointsandtheinterfacebetweentheveneerandtheprecastpanel(inadvertentlychangingtheraincontrolfromdrainedscreentoface-sealed.)

Whendealingwitholderbuildings,especiallythosehavingahistoryofwateringressproblems,theoriginaldesignandlatermaintenancerecordsshouldbeconsultedbeforeanewmaintenanceplanisinitiated.

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Figure6:Identification–Veneerpanelsduringinstallation.

Figure7:Olderveneerpanelsmayhavegapsbetweentheveneerunitsandtheprecastpanelsubstratethatallowwaterpenetrationbehindtheveneerandjointsealant.Theresultingwaterpenetrationcancausestainingattheedgesanddamagetotheveneerandinteriorfinishes.Newsystemsbondtheveneerintegrallywiththeconcreteanddonottypicallyexhibitthisdistress.

Thefollowingsectionusesthesetypesofprecastfacadestodescribetheinspectionandmaintenancerequirementsofeach.

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2.0InspectionandMaintenanceRequirements

WhatKindofMaintenanceisRequired?

Maintenanceisdefinedasworktorepairdeficienciesthatdevelopduringtheservicelifeofabuildingcomponent.Thisworkisassociatedwiththenormal“wearandtear”onabuildingratherthanworktoimproveabuilding–e.g.,throughrenovation.The“deficiencies”addressedbymaintenanceincludeissuesrelatedtoboththefunctionalperformanceoftheenclosure(asdescribedinSection1earlier)andalsotheaestheticperformance–howthebuildinglooksovertime.

Astheservicelifeofbuildingsandtheirenclosurecomponentstypicallyspandecades(andsometimescenturies),itishelpfultoconsidermaintenanceworkinseveraltimescales.Wecandividemaintenanceactivityintoseveraltypes:2

• CorrectiveMaintenance–Unscheduledmaintenancerepairstocorrectdeficienciesduringtheyearinwhichtheyoccur.Correctivemaintenanceisanongoingtaskandtypicallyinvolvessmall-scale,routineactivity.

• PreventiveMaintenance–Scheduledinspectionsandservicingundertakentoachievetheexpectedservicelifeofthebuildingandbuildingcomponents.Thesepreventativemaintenanceactivitiesincludeadjustments,localizedrepairs,and(ifrequired)componentreplacementtopreventlarge-scalefailuresandprematurereplacementofotherenclosurecomponents.Theseactivitiesareconductedwithafrequencyofoneyearorless,andtypicallydemandmodestinvestmentsoftimeandmoney.Preventativeactivity,whendeemedessential,mayreducethelong-termoperatingcostofthebuilding.

• RecurringMaintenance–Preventivemaintenanceactivitiesthatrecuronaperiodicandscheduledcycleofgreaterthanoneyear,buttypicallylessthantenyears.

2ThesedefinitionsareadaptedfromtheU.S.DepartmentoftheInterior’sguide“CommonDefinitionsforMaintenanceandConstructionTerms”.

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• ComponentRenewal–Preventivemaintenanceactivitiesthatrecuronaperiodicandscheduledcycleofgreaterthantenyears.Anexampleofthistypeofactivitywouldbethereplacementofsealantmaterialthat,asacomponent,hasashorterexpectedservicelifethanthesystemasawhole.

• EmergencyMaintenance–Maintenanceactivitiesthatareunscheduledrepairs,tocorrectanemergencyneedtopreventinjury,lossofproperty,orreturnanassettoservice.Theserepairsareinitiatedwithinaveryshorttimeperiodfromwhentheneedisidentified,usuallywithinhours.

WiththeobviousexceptionofEmergencyMaintenance,thegoalsoftheactivitiesdescribedaboveareto:

• Maintainanacceptablelevelofperformance• Delaythetimeandexpenseofrenewalormajorrenovation• Preserve,orevenenhance,thevalueofthebuildingassetovertime

CorrectiveandPreventativeMaintenancewilltypicallybeperformedbyfacilitystaff,buildingoperators,orbuildingowners.Largerbuildingsmayemployservicecontractorsforthismaintenancework.

RecurringMaintenanceandComponentRenewalactivitiesaregenerallyperformedbyservicecontractorsandinsomecasesmayincludeengineeringand/orcontractedArchitecturalandEngineering(A&E)servicesthatsupportplanning,design,andexecutionofmaintenanceactivities.

GeneralMaintenanceandInspectionRequirementsforPrecastEnclosures

Allbuildingenclosuresneedperiodicconditionassessmentsbybuildingmaintenancestaff.Thefrequencyoftheseassessmentsdependsgreatlyonthetypesofcladdingandothermaterialsused;theexposureofthebuildingtorain,wind,pollution,andotherenvironmentalfactors;therisksandconsequencesoffailure;and,ofcourse,onthepreferencesofthebuildingowner.Differentelevationsofthebuildingmaybeinspectedatdifferenttimeintervalstorespondtothevariableslistedabove.

Precastenclosuresystemscanbeexpectedtoperformforalongservicelifewithlittleornosignificantchangefromtheiroriginalspecifications.Itis,however,recommendedthatataminimumthefollowingmaintenanceandinspectiontasksbeperformedonanannualbasis.

DefinitionConditionAssessmentPeriodicinspectionbyqualifiedpersonneltofullydetermineanddocumenttheconditionofaconstructedassetandidentifymaintenanceneeds.

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1. GeneralCleaning

Thesurfaceofprecastpanels,likethesurfaceofmanyothercladdingmaterials(e.g.stone,light-colouredbrick,etc.)issusceptibletodirtaccumulationandstainingevenwhensomesurfacetreatmentisused.Glass,althoughnon-absorbent,istypicallywashedatintervalsofsixmonthstotwoyears.

Innormalbuildingmaintenance,careshouldbetakentoavoidcommonsourcesofstaining:

• Run-offwaterandcleaningagentsfromwindowcleaning• Leakagefromroof-orwall-mountedmechanicalunits• Saltsusedinsnowremovalatgradelevel• Dischargeorexhaustfrommechanicalandlaundryvents

Figure8:Exposedconcretesurfacesmaybestainedbyatmosphericpollution,biologicalsources,andleachingofchemicalsfromotheradjacentbuildingmaterials.

Topreservetheaestheticpropertiesoftheoriginalsurface,cleaningshouldbeconductedasrequiredbasedonvisualinspections.Thebodyoftheprecastpanelsshouldbewashedwhenthesurfaceofthepanelshasbecomediscolouredsufficientlytobeobjectionabletotheownersortenants.Thiscanbedoneonanelevationbyelevationbasisdependingontheextentandlevelofstaining.Thefollowingprocedureisrecommendedforconcretesurfacesthatdonothavespecialcoatings:

1. Wetthesurroundingconcreteusingcleanwatertopreventwashwater(containingdetergentsorchemicals)frombeingabsorbed.

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2. Pressurewashtheexteriorsurface,takingcaretoavoiddirectsprayonwindowsandpaneljointmaterial–sprayawayfromwindowsandjointsratherthandirectlytowardsthem.

Note:Iffinishesorsealershavebeenappliedtotheexteriorsurface,orifpigmentwasusedinthemanufactureoftheprecastpanels,carefultestingofthecleaningmethod,includingcleaningtreatmentsshouldbeperformedinasmallinconspicuousareapriortocommencingworkontheentirearea.

3. Forbuildingsthathavenotbeencleanedfrequentlyorthataresubjectedtoharshenvironmentalconditions,acidictreatmentorgrit-typecleanersmaybeused.AmildsolutionofTrisodiumPhosphate(TSP)willremovemoststubbornstaining.

Note:Somecleaningproductsmaybesubjecttospecialregulationsregardingtimeofuseandcleanupprocedures.Testthecleaningprocedureonasampletoensurethattheprecastpanelswillnotbedamaged.

Formorespecificinformationonremovingspecificstainsfromconcrete,see“RemovingStainsandCleaningConcreteSurfaces”(IS214),publishedbythePortlandCementAssociation(www.cement.org).

2. GeneralConditionAssessment

Thepurposeofaconditionassessmentistoidentifyanychangesfromtheinitialdesignandas-builtconditionorthepreviouslyrecordedconditionassessments,andtoensurethatthebuildingenclosurecontinuestoperformasdesignedandsatisfytheowner’sservicerequirements.Forprecastenclosures,anannualvisualassessmentconductedfromthegroundwiththeuseofbinocularsistypicallyallthatisneeded.Asvariouscomponentssuchasjointsealantandwindowsystemscomeclosetotheendoftheirexpectedservicelife,anassessmentconductedfromaswing-stageorelevatedplatformiswarranted.

Ensurethatadequatesafetymeasuresaretakenwhenperformingmaintenanceandrepairactivitiesontheexteriorwallsfromelevatedworkplatforms.

Itisrecommendedthatallsignsofdeteriorationofthepanels,sealantjoints,orinterfaceswithotherenclosureelementsbedocumentedaspartoftheseconditionassessments.Observeandrecord(photographs)theconditionofbuildingelements(particularlythosethatarepartoftherainwatermanagementsystem,suchasroofing,parapets,balconies,andoverhangs)whosefailureorgraduallossofperformancecouldaffectthefuture

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performanceoftheprecastsystemandtheenclosuresystemasawhole.Allofthisinformationshouldbeconsideredwhenmakinglongtermrepairandmaintenanceplans.

The“PlanningandDocumentation”sectionofthismanualprovidesanexamplechecklistthatcanbeusedtostructuretheseconditionassessments.Moreinformationisprovidedinthefollowingsectionontheinspectionof,andmaintenancefor,specificcomponentsoftheprecastenclosuresystem.

RequiredInspectionandMaintenancebyComponent

Thereareseveralkeycomponentsofaprecastenclosuresystemthatshouldbeinspectedonaregularbasisandmayneedmaintenanceeitherwithinayearaspreventativeactionorascomponentrenewal.Adescriptionofthemaintenancerequiredandsuggestedtimeframesforinspectionhavealsobeenincluded.

PrecastConcreteUnits

Otherthantheperiodiccleaningrecommendedabove,verylittleinthewayofmaintenanceisrequiredforprecastconcretepanels.Thereare,however,severalissuesthatmayoccurwithprecastpanelsovertheservicelifeoftheenclosure.Themostcommonissuesarediscussedbelow.

Figure9:Exampleofstressfracturepattern

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Whilerare,fractures(Figure9)mayoccurovertheservicelifeofthebuildingduetomovementofthepanelsystemorlong-term'creep'ofthebuildingstructure(oneormorepanelsbearingononeanother).Ifthereissignificantdamage,thefracturedpanelmayneedtobereplaced.Thisisanexpensiveandlong-termoption.Inmanycases,thedamagedpanelmaybelocatedoutofviewandnotofimmediateconcern.However,thefractureshouldbesealedimmediatelytopreventingressofwaterthatmayleadtofurtherdamage.Astheforcecausingthefracturemaybeactive,thepanellocationshouldalsobenotedintheconditionassessmentandmonitoredinfutureassessments.Theforcecausingthefracturemayalsobereducedoreliminatedbygrindingorsawingthejointifthepanelsareindirectcontactwithoneanother.Evidenceofspalling(detachmentoflargeconcretepieces)maybeapotentiallifesafetyissueandrequireimmediaterepair.

Crackingofprecastpanelsshouldalwaysberecordedintheconditionassessmentandanestimate(preferablyameasurement)ofthecrackwidthshouldbenotedsothatany“movement”–wideningorlengthening–ofthecrackcanbedetermined.

Cracksthatarenotmoving(or“progressing”)canbesealedwithaqualitysealantafterpropersurfacepreparation(followsealantmanufacturer’sinstructions).Deepcracksandanycracksthataremovingshouldbeexaminedandsuitablerepairmethodsshouldbeidentifiedbyastructuralengineer.

Thermalmovementsoftheenclosurecomponentsormovementofthebuildingstructurecanoccasionallycreatecrackingordistresswherepanelsmeet,orattheirmetalconnections.Itisrecommendedthatastructuralengineerinvestigateallsignsofdistressrelatedtomovement.

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Figure10:Afracturedpanelsealedtopreventwateringress.Ifastructuralengineerassessesthispaneltobesafe,itwillremainavisualissuebutfurtherdamagecanbemitigatedbysealingthecracks,allowingforcontinuedperformanceofthepanel.Cleaningofthepanelpriortosealingwillgreatlyreducethevisualissues,butrarelytotallyeliminatethem.

Chippingofpanels,especiallyatexposedcornerscanbecausedbyvehicles,snowclearingandmaintenanceequipment(Figure11).Althoughanaestheticconcern,thereisusuallynodirectimpactonthefunctionalperformanceofthepanel.Repairofthisdamagemaybepossiblebygrinding,orreshapingoftheedgewithanappropriatecementitiouspatchingcompound.Thecolourofthepatchingcompoundcanbeadjustedtomatchthecolourofthepanelandreducethevisualimpactofthepatchedarea.Bollardsorsimilarmechanicalbarriersareoftenprovidedinnewdesign,orretrofittoexisting,toavoidthistypeofdamage.

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Figure11:Chippingofpaneledges.Physicalimpactcanleadtodamagetopaneledges,especiallyatcorners(aspicturedonleft),andwheretheconcretehasbeenformedintoasharpedgeforaestheticorfunctionalreasons.Carefulpatchingandcleaning,asshowninthephotoontheright,canfixsuchdamage.

PanelAttachmenttoMainStructure

Large-formatprecastpanelsareattachedtothemainbuildingstructurewithembeddedmetalcomponents.Astructuralengineer(havingexperiencewithprecastconcretepanelsystems)shouldberetainedtodefinetherequiredfrequencyofinspectionanddevelopaninspectionplanthatwillverifythefunction,freedomofmovement,andconditionofconnectionsforthesubjectbuilding.

Inmostcases,structuralconnectionsarenotvisiblewithoutremovaloftheinteriorfinish.Originalshopdrawings,ifavailable,oftenwillaccuratelylocatethestructuralembedsthatreceivetheconnections.

Thenumberandsizeofopeningscanthereforevarysignificantly,andthecostwillvaryaccordingly.Theselectionofthenumberandtypeofopeningsinspectedwilldependheavilyonclimate,exposure,corrosionprotectionoftheconnectors,clientriskconcerns,pastinspections,andhistoricalperformance.

Animportantcriteriaforassessingtheintensityandfrequencyofinspectionisthetypeofprecastwallpanel.Drainedprecastsystemsexposetheconnectorstomorewatermoreoftenandmayrequiremorefrequentinspections.Connectionsofdouble-wytheinsulatedpanelstothestructureareentirelywithintheenclosureandrequirethesameintensityandfrequencyofinspectionasstructuralsteelconnectionswithinthebuilding.Architecturalprecastpanelswithconnectionsembeddedinsprayfoamhavebecomemorecommon;whilethisfoamlayerprotectstheconnectionfrombothcondensationandleakingwater,italsohidestheconnectionfrominspection.Inspectionswillrequirethisfoamtobecutawayandreapplied.Untilfurtherexperienceandconsensusisdeveloped,aninspectionintervalof10to25yearsissuggestedforarchitecturalprecastpanelconnections.

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Theinspectionshouldallowthestructuralengineertocategorizethelevelofdamagealongwithdegreeofriskposedandactionrequired,suchas“Significantlossofsection,dangerouscondition–immediateactionrequired”,or“Corrosioninhibitspanelexpansion,repairnecessaryaspartofbuildingrenewal”,or“Slightsurfacecorrosion,monitorprogress–inspectagainin10years”.

Figure11:Panelattachmentsatatypicalexteriorcorner.Forthestructuralsystem,theinspectionshouldincludeavisualinspectionofallstructuralcomponentsbyastructuralengineerexperiencedinthedesignandconstructionofprecastconcretestructures.Thisconnection,photoontheleft,isnotwellprotectedfromcorrosion,andhencewouldrequiremorefrequentinspectionsthantheindustryrecommendedhot-dipgalvanizedconnectionseeninthephotoontheright.

Toaccessthebacksideoftheprecast,thestructuralengineermustlistthelocationswhereexploratoryopeningsarenecessary;theexploratoryopeningsmustbemadeeveniftherearenosignsofdamage.Theobjectiveoftheopeningsistoverifytheconditionofthestructuralconnections.Hence,theopeningsmustallowverificationoftheconditionsofallthematerialsandcomponentsthatcouldposeasalife-safetyrisktopersons,namelyfasteners,anchors,headers,etc.

Inthevastmajorityofcases,avisualinspectionconfirmingtheconnectionisappropriateforitspurpose(sizedfortheload,designedtoalloworrestrainmovement)andingoodcondition.Scrapinganysurfacerusttoconfirmdepthofcorrosionandremainingsectionwouldbeaminimumlevelofeffortforanyconnectionfoundinlessthanpristinecondition.Ifnecessary,samplescanbetakenandsenttoalaboratoryforfurtheranalysis.Observationsofthepresenceofsignsofpastorcurrentwettingorwettingmechanismsshouldberecorded.

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JointsforFace-sealedFacades

Alljointsealantsmayrequireinspection,maintenanceandrepair.Forface-sealedfacades,theexposedjointsealantsaretheonlylineofdefenseagainstwaterintrusionandsoregular,rigorousevaluationofthejointsealantiswarranted.

Potentialmaintenanceissuesarewaterleakagethroughthejoint,visibleseparationofthesealantfromtheconcrete,andcrackingortearingofthesealant.Figure12belowexplainscommontypesofsealantfailures.

Figure12:CommonTypesofSealantFailure(StraubeandBurnett.BuildingScienceforBuildingEnclosures.BuildingSciencePress,Westford2005)

Sealantdeteriorationcangenerallybedetectedthroughvisualinspectionlongbeforejointshavetotallyfailedandallowwaterpassage.Buildingownersandmanagersshouldkeepaccuraterecordsofwhentheexteriorsealantswereinstalled,theexpectedusefulservicelifeofthesealantaccordingtothesealantmanufacturer,andthetime,nature,andresultsofeachinspectionduringservice.

Aninitialpost-constructioninspectionshouldbeundertakenasacheckontheinstallationquality.Subsequentannualinspectionsshouldthenbeconducted.Inmanycases,theannualevaluationcanbeundertaken(usingbinoculars)fromthegroundandtheroof.Oncerepeatedorextensivefailuresofthesealantshavebeenrecordedorthesealantshavereached75%oftheirpredictedusefulservicelifeaccordingtothesealantmanufacturer,amoreextensiveevaluationshouldbeperformed,includingtheuseofswingstagesoraccessplatformstoadequatelyobservethebuildingsealantjoints.Contactthesealantmanufacturerformoreinformationaboutsealantservicelifeandconditionassessment.

Figure14showsdetailsofawell-designed,flexiblesealant-on-backerrodseal.Thefollowingshouldbenoted:

• Abackerrodofclosed-cellpolyethylenefoamshouldbeused(useofotherbackerrodmaterialsmaynotpreventthesealantfromadheringtothebackerrod).Thebackerrodshouldbesufficientlycompressedinthejointtoensurethatitwillremaininplaceduringapplicationofthesealant.Thesealantistobeshapedby,butnotbondedto,thebackerrod.

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• Surfacesorsubstratestowhichthesealantwilladheremustbecleanandsound.Thesurfacesmustbecapableofacceptingsealantadhesion.Forexample,sealantsdonotbondwelltosyntheticwaterproofcoatingsbecausethesecoatingsaredesignedtoavoiddirtcollection,waterabsorption,graffiti,etc.

• ThesealantshouldbeappliedandshapedasshowninFigure14.Thesealantshouldbetooledinaconcaveformtoensurecompactionandgoodcontact,tocreateasurfaceskin,andtoproduceanhour-glassshape.Thehour-glassshapehelpsensurethatthestressinthesealantisgreatestinthemiddleandleastatthebondsurface.Thesealantshouldbesufficientlyflexible,strong,anddurabletoallowthenecessarymovementunderallclimaticconditions.

Itisimportantthatthebondcontactdimensionbenolessthanhalfthewidthofthejointtobesealed.Inotherwords,ifJisthedesignjointwidth(Figure14),thenthedimensionofthesealantcontacttotheprecastshouldbegreaterthanorequaltoJ/2.Althougha2:1ratioofdepthtobonddimensionisconsideredidealbyleadingsealantmanufacturerstheminimumdepthofthesealantmustalsobecontrolled,toabout6mm.

closed-cell backer rod,compressed about 25%

hour-glass shaped sealantbead has good bond to

sides of joint and no bondto the backer rod, while thenarrow centre ensures thesealant is flexible enough

to allow joint movement

> J/2

Jprecast panel

Figure13:TypicalSealantandBackerRodJoint(StraubeandBurnett.BuildingScienceforBuildingEnclosures.BuildingSciencePress,Westford2005)

Installationproceduresshouldfollowthespecificationsofthesealantmanufacturerandcanbeexpectedtovaryfrommaterial-to-materialandfromseason-to-season.Sealantsshouldnotbeinstalledduringextremesofheatorcold.Installationqualitywillbebestataverageseasonaltemperatures.SeeFigure14.

Althoughsomeminorrepaircanbeperformedbymaintenancestaffonanannualbasis,thisworkshouldbelimitedtoremedialworkbetweenreplacements.Anexperiencedservicecontractorshouldberetainedforsurfacepreparationandinstallationofjointsealants.

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Swing Season (mean condition)

1.25 J J 0.75 J (installed condition)

Cold Weather Season Warm Weather Season (mid winter) Enclosure (mid summer) Enclosure contracts, joints widen expands, joints narrow

J 0.75 J 0.50 J (installed condition)

2.0 J 1.50 J J (installed condition)

Figure14:InstallationConditionsbySeason(StraubeandBurnett.BuildingScienceforBuildingEnclosures.BuildingSciencePress,Westford2005)

JointsforDrainedFacades

Indrained(two-stage)joints,thepotentialconsequencesofafailedexteriorsealaremuchlessduetothepresenceoftheinteriorseal;hencetheinspectionandmaintenanceintervalcanbeincreasedforthesesystems.

Figure15:Detailsoftwo-stagejointatdrainandventhole.Notetheopenjointallowsforeasydrainage.Plasticweeptubesaresometimesinsertedtoalerttradesthatanopeningisintentionalandnottobesealedover,but

suchtubesdonotdrainaswell,astheycanfillupwithinsects/spidersanddustovertime.

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Ingeneral,theinnersealshouldbepositionedatleast25mm(1inch)behindthebackerrodoftheoutersealtocreateawell-ventilatedairgap.Thisrequirestheinstallationoftooledsealantonabackerrodinstalledatleast75mm(3inches)behindtheouterface.

Weepholes,withaminimumdimensionof12mm(1⁄2inch)bythejointwidthshouldbeusedtofacilitatedrainage.Itismostcommontoprovidetheweepholesintheverticaljoints.AbeadofsealantistiedtotheinteriorverticalsealantbeadasillustratedinFigure16.Thesealantshouldbeinstalledwithanoutwardslopeofatleast1in2(i.e.almost30degrees)toencourageoutwardflowofwaterandresisttheentryofwind-drivenrain.

Whereweepholesarenotprovided,orwheretheyareblockedbysealantreplacement,waterpenetratingtheassemblywillbeforcedtofindotherdrainagepathstotheinteriororexterior(Figure16).

Figure16:Drainagewithoutweepholes.Thehorizontalsealantjointinthephotototheleftiscrackedandallowswatertodrainfromunderneaththewindowsillabove.Thisisnotaplanneddrainagepath.

Anextensiveamountofinformationonjointsealantmaterialselection,installation,andcommonproblemsareavailableinCPCI’sArchitecturalPrecastConcreteWalls:BestPracticeGuidebyM.E.Hachborn.

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MetalFlashingandDrainageGaps

Drainedprecastenclosuresystems,andotherpartsofthebuildingenclosuresuchasparapets,overhangs,andwindowdetails,makeuseofmetalflashingtocreatewater-sheddingdripedges.Metalflashingcomponentsaretypicallyprefinishedanddonotrequirere-finishing.Metalflashingisusuallylight-weightandsubjecttophysicaldamageanddeformationduetobuildingmovements.

Asimplevisualinspectionwillindicatedamage.Repairof“through-wall”flashing(i.e.,aflashingcomponentthatextendsfromadrainageplanewithinthewalltotheexterior)maybecostprohibitiveandthismayprecludereplacement.However,ifthedamagetotheflashingincreasesrainwaterloadingoftheenclosuresystembelow,itmaybenecessarytoundertaketherepairorriskearlydeteriorationoflargerportionsofthebuildingenclosuresystem.

AttachmentstoPrecastPanels

Buildingelementssuchassignage,posts,andrailingsthataredirectlyattachedtotheprecastpanelsbywayofmetalfastenersshouldbecarefullyinspected.

Holesforfastenersshouldbefilledwithanchoringcementorsealanttopreventtheingressofwater,whichcouldcausefreeze-thawdamageorcorrosionofthefasteners.Bothissuesmayleadtocrackingoftheconcretesurfaceandfurtheringressofwater.

Replacefastenersonlywithmaterialthatissuitablefortheexposureconditions(e.g.,stainlesssteelfasteners)andcompatiblewiththeadjacentmaterials.

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Figure17:Attachmentstoprecastpanelsmaybestructurallyviablebut,iftheattachmentpointsarenotsealedtopreventwaterintrusion,thiscouldleadtocrackingoftheprecastpanel.

Grade-levelConditions

Atgradelevel,precastpanelsandotherenclosurecomponentsaresubjecttoarangeofdamagemechanismsincluding:

• Physicalimpactfromvehiclesandpedestrians• Stainingfromhumanandanimalactivity• Contaminationfromde-icingsalt• Additionalwaterloadingfrom:

o drainageongradeo capillaryor“risingdamp”frombelowgrademoisturesourceso splashbackfromhardsurfacesadjacenttothebuildingo landscaping

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3.0PlanningandDocumentationEffectivemaintenancerequiresplanningthatstartsasearlyasthecompletionofconstructionandissupportedbycleardocumentation.Thebuildingowneroroperatorshouldmaintainthefollowingdocumentstoassistwithplanningandthedevelopmentofrepairprocedures:

• Architectural,StructuralandMechanicalServiceDrawingsandSpecifications• Shopdrawingsfortheprecastpanelsandconnectiondetails,including

componentsconstructedaspartofthebuildingstructure• Shopdrawingsforallotherbuildingenclosurecomponents• “As-built”drawingsreflectingchangesfromthedesigndrawingsand

specifications,madeduringconstruction• Materialdatasheetsandsupplierinformationforsealantsandcoatings• Arecordofallreportedperformanceproblemsrelatedtothebuilding

enclosureandotherbuildingsystems• Arecordofmaintenanceandrepairactivitysinceconstruction

Thesedocumentswillbeusedtounderstandtheinitiallevelofperformanceexpectedfromtheprecastenclosureandthestepstakentomaintainthisperformance.Amaintenanceprogramcanbeestablished,whichshouldinclude:

1. amaintenancebudget,2. assignmentofpersonnelandservicecontractorstoimplementtheprogram,3. ascheduleofmaintenanceactivities,4. recordingprocedurestodocumentmaintenanceactivity,and5. areviewsystemtooverseetheprogram,whichmayincludeperiodicthird-

partyreview.

Themaintenanceprogramshouldbereviewedannuallyandrevisedasrequiredtoaccountfornewinformationgatheredfromtheconditionassessmentsandchangestotheoperationofthebuilding.

Intheeventofamajorperformanceproblem,theserecordsandthemaintenanceprogramwillallowforafaster,moreaccurateassessmentoftheproblemandprovidesignificantcostsavingsduringthedesignandexecutionoftherepairs.

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Sample Inspection and Maintenance Plan for Exterior Precast Enclosures  

Building Name and Location:

Activity Suggested Frequency of Inspection

Exterior Visual Inspection

Review exterior of precast panels for signs of staining, discolouration, and distress, such as spalling, cracking or delamination of the concrete. Pay close attention to cracks and construction joints. Contact structural engineering consultant to review large cracks and significant areas of spalling if required.

Ensure that adequate safety measures are taken when performing maintenance and repair activities from elevated work platforms.

[Inspect annually.]

Minor Chipping or Crack Repair of Precast Panels

Locally repair precast concrete panels as required.

[Inspect annually; repair as needed.]

Cleaning of Precast Panels

Clean exterior coated concrete panel surfaces. Power washing equipment should be used with care at joints and interfaces.

Use a mild solution of Trisodium Phosphate (TSP) to remove stubborn staining.

[Visually inspect annually from the ground; clean if required]

Recoating of Precast Panels (Only for Previously coated/sealed panels)

Repair of delaminated or spalled concrete should be carried out prior to recoating. Reapplication of the protective coating as required, including preparation of the concrete substrate.

Retain sufficient stock of coating and sealant products on-site for localized maintenance and colour matching purposes.

[Visually inspect annually from the ground. Recoat if necessary according to manufacturer's instructions.]

Visual Inspection of Joint Sealants

Inspect a random sample of exterior joint sealants for signs of deterioration and leaks, selecting sufficient examples to provide a representative assessment, including each elevation.

[Initial inspection in four years; thereafter, inspect every two years for polyurethane and every 5 years for silicone. This schedule is to be followed unless sealant deterioration is noted, in which case inspections should be conducted annually.]

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Inspection of Panel Anchorage/ Connection to Main Structure

Visually inspect for corrosion damage. This may require removal of interior finishes and/or inspection at locations such as unfinished interiors, closets, mechanical rooms, etc.

[Initial inspection frequency of approximately 10 to 25 yrs (for example, 10 years for single-wythe panels, since the connections may be more susceptible to condensation, and 25 years for double-wythe insulated panels with hot-dip galvanized connections, since the connections are on the protected side of the building enclosure).

Subsequent inspections should be every 5 years unless significant deterioration is noted, in which case, inspection frequency should be increased to biannually or annually depending upon significance of corrosion.]

Visual Inspection of Miscellaneous Steel (Attached to Exterior of Panels)

Check handrails, stair treads and landings, metal or precast stair members, walls, signage, and roof for deterioration. Check concrete adjacent to all metal-to-concrete connections for signs of distress.

Check exposed metal for corrosion of bearing plates and welded connections. Check grouted connections for rust stains.

[Inspect annually]

Review adequacy of maintenance inspections annually. Update the maintenance record based on environmental conditions, experiences over the preceding year and feedback from service contractors.

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Example Precast Enclosure Inspection Checklist – by Component 

Building Name:

Building Location:

Precast Enclosure Type and Rain Control Strategy

Date of Inspection

Name & Credentials of Inspector / Organization

Have design drawings been reviewed for design intent? Which?

Have previous inspection reports been reviewed? Which?

Important Note: Ensure that adequate safety measures are taken when performing maintenance and repair activities on the exterior walls when working from elevated work platforms.

For each item on the checklist identify which area of the enclosure is being referenced, i.e., elevation/orientation, floor, lateral distance from feature such as corner, or if the observation applies to all.

Precast Concrete Units

1. Inspect face of precast concrete units for large cracks. Inspection may be conductedfrom ground level with the use of binoculars. Conduct the inspection systematically andcarefully note location (including orientation and floor level) of cracks observed.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Cracking of precast panels should be recorded and a measurementof the crack width should be noted so that any “movement” – widening or lengthening – ofthe crack can be determined. Cracks that are not moving (or “progressing”) can be sealedwith a two-part polyurethane or a silicone sealant after proper surface preparation (followsealant manufacturer’s instructions). Deeper cracks and cracks that are moving should beexamined and suitable repair methods should be provided by a structural engineer.

Comments:

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2. Inspect face of precast concrete units for staining and (if applicable) the condition of theexterior finish.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Some stains may be cleaned using a mild solution of TrisodiumPhosphate (TSP). Other cleaning solutions may be required. Power washing equipmentshould be used with care at joints and interfaces. Cleaning should first be trialed in aninconspicuous location. Exterior finishes that were previously coated may also be restoredby recoating (follow the manufacturer’s recommendations).

Comments:

Panel Attachment to Main Structure (i.e., panel anchors)

3. Where possible, visually inspect metal structural connections. Note that a licensedstructural engineer must be retained to conduct inspections of structural components. Ifwater intrusion has been detected on the building interior, remove interior finishes toview structural connections. Panel anchors are typically made of corrosion-resistantmaterial or have corrosion-resistant coatings – little or no corrosion should be expected.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Retain licensed structural engineer for inspection.

Comments:

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Joints for Face-sealed Facades (i.e., face sealed)

4. Inspect condition of joint caulking bead between panels, at window openings, andbetween precast and other enclosure materials. Look for cracking or tearing at thecentre (cohesive failure) or edges (adhesive failure) of the caulking.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Face-sealed systems depend on the joint caulking bead to preventingress of rainwater. Damaged or missing caulking must be repaired immediately. Anexperienced service contractor should be retained for surface preparation and installationof joint sealants.

Note that tearing of sealant joints may be caused by unexpected movement of the precastwall panels. If repaired joints show damage soon after the repair, ask a structural engineerto investigate further.

Comments:

Joints for Drained Facades (i.e., two-stage joints)

5. Inspect condition of exterior sealant beads between panels, at window openings, andbetween precast and other enclosure materials. Look for cracking or tearing at thecentre (cohesive failure) or edges (adhesive failure) of the sealant.

☐ No issues observed.

☐ Issues observed.

Recommended Action: The exterior sealant bead in a drained, two-stage joint providesprotection from the elements for the inner sealant bead located towards the interior side ofthe precast panel. Replacement is not needed for minor cracking or edge separation.Missing sealant or wide gaps should be replaced. An experienced service contractorshould be retained for surface preparation and installation of joint sealants.

Comments:

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6. Inspect condition of interior sealant bead. Where possible (at drainage or weep hole locations) look for complete sealant beads extending from interior to exterior.

☐ No issues observed.

☐ Issues observed.

Recommended Action: The interior sealant provides water and air control layer between panels and must be continuous to function effectively. Replace if damage is observed. An experienced service contractor should be retained for surface preparation and installation of joint sealants.

Note that tearing of sealant joints may be caused by unexpected movement of the precast wall panels. If repaired joints show damage soon after the repair, ask a structural engineer to investigate further.

Comments:

Metal Flashing and Drainage Gaps

7. Inspect metal flashing for damage. Look for bent or damaged metal, flashing lifted and causing drainage towards the building, and signs of staining below joints in metal flashing pieces.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Bent or displaced metal flashing can typically be repositioned, reformed or reshaped. Gaps between horizontal runs of flashing material may require sealant to prevent water concentration and staining.

Comments:

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Attachments to Precast Panels

8. Inspect attachment point of signage, canopies, posts, and railings. Note corrosion ofmetal fasteners.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Repaint fasteners or replace fasteners with material that is suitablefor the exposure conditions (e.g., stainless steel). Note that for the attachment of largeobjects and railings, corrosion of metal elements may weaken the structure and create asafety hazard. Consult a licensed structural engineer for recommendations.

Comments:

9. Locate any holes where fasteners have been removed from attachment to precastpanels.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Holes from removed and unnecessary fasteners should be filledwith anchoring cement and/or sealant to prevent the ingress of water, which could causefreeze-thaw or corrosion of the fasteners.

Comments:

Grade-Level Conditions

10. Inspect panels for salt and “splash back” water staining near walkways, roadways, andlandscape areas.

☐ No issues observed.

☐ Issues observed.

Recommended Action: Staining may be cleaned using a mild solution of TrisodiumPhosphate (TSP). Other cleaning solutions may be required. Power washing equipmentshould be used with care at joints and interfaces. Cleaning should first be trialed in aninconspicuous location. It is important to address the cause of the staining. This mayrequire a change to winter maintenance, modification of the surface at grade level, or therepair or addition of flashing.

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Comments:

11. Inspect panels near entrances, loading and service areas for physical impact damage orfracture.

☐ No issues observed.

☐ Issues Observed.

Recommended Action: Damage to precast panels should be repaired to prevent wateringress and further damage. Bollards or steel plates may be added to protect panels fromfurther impact damage.

Comments:

12. Look for changes to surface water drainage caused by changes to landscaping,settlement at grade-level, and improvements to neighbouring properties.

☐ No issues observed.

☐ Issued Observed.

Recommended Action: Provide minimum 2% slope away from building enclosure. Ifnecessary, install surface drainage feature (swale, berm, etc.) to direct surface water awayfrom building.

Comments:

Name of Inspector: Company:

Signature: Report Date:

Reviewed By: Company:

Signature: Review Date:

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4.0ResourcesandReferencesCPCIResources

TheCanadianPrecast/PrestressedConcreteInstituteprovidesanumberoftechnicalreferencesforprecastconcreteenclosures.Thefollowingdocumentsareaccessibleinprintandonlineforyouruse.

ArchitecturalPrecastConcreteWalls:BestPracticeGuidebyM.E.HachbornEngineering http://www.cpci.ca/en/resources/technical_publications/

HighPerformingPrecastConcreteBuildingEnclosures-RainControlbyDr. JohnStraube,P.Eng.http://downloads.cpci.ca/57/downloads.do

GeneralPrecastandBuildingScienceResources

Thereareanumberofgeneralbuildingscienceresourcesthatwillassistthebuildingowner/operatorinunderstandingtheperformanceofprecastconcreteenclosuresandothercomponentsofthebuilding.Manyofthefollowingresourcesarealsoavailableonline.

CSAA23.4-16,Precastconcrete-Materialsandconstruction,CanadianStandardsAssociation,Toronto,Ontario,2016.

NPCA.PrecastConcreteArchitecturalRepairGuide.NationalPrecastConcreteAssociation:Carmel,IL,2013.

Straube,J.F.,HighPerformanceEnclosures:DesignGuideforInstitutionalCommercialandIndustrialBuildingsinColdClimates.BuildingSciencePress:Somerville,Massachusetts,2011.

Straube,J.F.,RainPenetrationControlPracticeGuide.OntarioArchitectsAssociation:Toronto,Ontario,2005.

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CPCITechnicalSupportHelpDesk

CPCItechnicalhelpdeskservicesprovidetechnicalinformationabouttheuseofprecastandprestressedconcreteproducts,throughinvestigationsandresearchrelativetoapplicationsofprecastandprestressedconcreteandengineeringprocessesforimprovementinthedesign,manufactureandinstallationofprecastproducts.

CPCIhelpdesksupportandcustomersupportarepartofacomprehensiveCPCIcustomersupportprogram.Pleaseemailusathelpdesk@cpci.caorcallusat1.877.YES.CPCI(1.877.937.2724).

RDH Building Science Inc.167 Lexington Court, Unit 5Waterloo, ON, CanadaN2J 4R9Tel: 519.342.4731

www.rdh.com

Canadian Precast/Prestressed Concrete InstitutePO Box 24058 HazeldeanOttawa, ON, CanadaK2M 2C3Tel: 613.232.2619, Toll free: 877.937.2724

www.cpci.ca

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DISCLAIMER: Substantial effort has been made to ensure that all data and information in this publication is accurate. RDH Building Science Inc. cannot accept responsibility of any errors or oversights in the use of material or in the preparation of architectural or engineering plans. The design professional must recognize that no design guide can substitute for experienced engineering and professional judgment. This publication is intended for use by professional personnel competent to evaluate the significance and limitations of its contents and able to accept responsibility for the application of the material it contains. Users are encouraged to offer comments to RDH Building Science Inc. on the content and suggestions for improvement. Questions concerning the source and derivation of any material in the design guide should be directed to RDH Building Science Inc..