b'Technical Article Better Understanding of AdhesionRecent research shows vapor retarderBy Mark S. Grahamadhesion to new concrete roof decks varies Thefollowingarticleoriginallyoverseetestspecimenpreparationroof deck and vapor retarder speci- vapor retarder type and conditioning,thetwo-plyBURmembrane appearedintheMarch2023issueand conduct vapor retarder adhe- mens were conditioned at standardwere tested. The average of the fivesampleexhibitedgreateradhesion ofProfessionalRoofingmagazine.siontesting. laboratory conditions for 60 days.specimensresultsareshowninthantheself-adheringvaporre-It is reprinted here with permissionTen6-inch-thickconcreteroofFortheremainingconcretedeckthefigure. tarder samples. Only sample manu-from the National Roofing Contrac- deck specimen sets were poured usingandvaporretardersets,insulatedThetestingshowsadhesionoffacturer 3-SA membrane exhibited tors Association. normal-weightstructuralconcrete.enclosures were constructed on thevaporretarderstoconcretedecksgreateradhesionthanthetwo-ply I nAnevolutionofknowledge,Thetopsurfacesoftheconcretebottoms of the specimens and heatvaries widely. For four of the five va- BUR membrane samples after tem-February2022issue,Idiscussedspecimens werefloat-finished. was applied, resulting in a 30-degreepor retarders, the results of the tem- perature differential conditioning.NRCAsresearchexaminingAfter 28 days of curing at stan- Fahrenheit temperature differentialperaturedifferential-conditionedItshouldbenotedallsamples roofing-relatedproblemswithdard laboratory conditions, a two-plyacross the bottom to the top of thesampleswerelowerthanthelab- exhibited adhesion well in excess of moistureinconcreteroofdecks.built-up membrane was applied tospecimens.Thistemperaturedif- oratory-conditionedsamples.Forwhat is necessary to achieve Class 90 OneareawhereNRCAconsideredtwo of the concrete roof deck speci- ferential created a net vapor pres- samplemanufacturer3-SAmem- (FM 1-90) uplift.additionalresearchtobenecessarymensandfourdifferentmanufac- sure drive from the bottoms to thebrane, the temperature differential-was addressing the adequacy of vaporturersself-adheringvaporretardertops of the specimens. This sameconditionedtestspecimenstestedRecommendationsretarderadhesiontonewlyplacedproducts were applied to the remain- netvaporpressureassessmenthigher than the specimens that hadBecauseadhesionofvaporre-concrete roofdecks. ing concrete roof deck specimens inconcept also was used in NRCAsbeen laboratory-conditioned. tarders to concrete decks varies, de-NRCA has since undertaken thistwo specimens sets. For each of theearlier research. Iconsiderthetwo-plybuilt- signers should specify vapor retard-research,whichprovidesdesignersself-adheringvaporretardertypes,After60daysofconditioning,uproofmembranesamplestobeers after considering vapor retarder with some guidance for proper vaporthemanufacturersrecommendedthe vapor retarder specimens weresomewhat baseline control samples.adhesion at the time of application retarder selection. primerwasused,andinstallationscut to size, a load frame was appliedHistorically, the U.S. roofing indus- and while in service.were done in accordance with manu- and a calibrated pull tester was usedtryhassuccessfullyusedtwo-plyAlso, manufacturers should in-Adhesion Research facturers installation instructions bytotesttheadhesionofthevaporBUR membranes as adhered vaporcorporate some form of vapor drive NRCA contracted with SRI Con- an experienced roofing contractor. retarders to the concrete roof deckretarders over concrete roof decks.conditioningassessmentintheir sultantsInc.,Waunakee,Wis.,toOne set of each of the concretespecimens. Five specimens of eachIn the laboratory-conditioned test- productdevelopmentsandassess-Wind Uplift TestedFOR CONTRACTORSModular Vegetated Roofing Systems ThermographyLeak DetectionUplift / Pullout TestingWind DesignShop Drawing EngineeringOTTAWAKINGSTONLONDONMONTRALATLANTICmail@fsaeng.comliveroof.ca www.fsaeng.com22ONTARIO ROOFING NEWSISSUE 2 2023 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'