b'the failure mode was determined to be due to the membrane fas tener having pulled out from deck, as shown in Fig. 10. The second specimen was installed on 20ga, 550 MPa steel deck and passed a sustained pressure of 8.62 kPa (180psf).Q7: WHAT IS THE ROLE OFMEMBRANE?Common membranes are thermoset, thermoplastic, and MB. The membrane must have adequate strength to withstand the stress from wind uplift. The physical/mechanical properties of a membrane such as thickness and tensile strength vary from product to product depending on the chemical composition and the reinforcement materials. As shown in Fig. 11, the membrane was stretched around the fastener plates, leading it to pull out from the fastener plate; this is known as the cookie cut failure. In Figure 7. Force resistance link diagram: partially attached (hybrid) membrane roofing system. this case, the mem brane was the weakest link for that roofing system. Replacing it with a thicker and/or higher tensile strength membrane will help to increase the wind uplift resistance of thesystem.Membrane seam strength is an important parameter that influences wind uplift resistance in MARS. The seam must resist flutter ing and pulling forces due to wind uplift force. Some manufacturers supply membranes with factory seams, but most of the manufact urers require seaming during construction. There are three different types of seam applica tion methods for MARS. Thermoplastic mem brane seams are hot-air welded by a robotic machine. Thermoset membrane seams have tape and/or adhesive. MB mem brane seams are heat air welded. The SIGDERS research showed that using improper speed and temperature for hot/heat air welding results in a very weak seam, as shown in Fig.12.Manufacturers have invented new seam application technologies such as self-adhered seam or torch-free seam in recent years, with claims that the new seam application technol-ogies are better than the traditional methodsFigure 8. Force resistance link diagram: adhesive applied membrane roofing system. Further research is needed to investigate the Technical Article welding window (temperature and speed), the influ ence of ambient temperature tomembrane is bonded to culator that conservatively estimatesroof self-adhered seam and torch-free seams on wind the wind loads on roofing claddings,thesubstrateusingadhesives, and the first version was developedand a minimum of one com-uplift resistance.using an RCI Foundation grant. ponentbelowthemembrane For the MARS with thermoplastic membrane,attachedto Note:Designingtheroofsystemisintermittently there are two seaming techniques, one-side weld accordingtoultimatelimitstatesupporting structure using fas-(ULS) requires multip -s cation of 1.4teners, as shown in Fig. 4.(OSW) and double li ide weld (DSW), as shown (principal wind load effect factor) toAdhesive Applied membrane in Fig. 13. The SIGDERS research showed thethe wind loads for various zones. RoofingSystem(AARS): roofing system with DSW performed better than Step 2: Select the Roofing System asysteminwhichtheroof OSW. DSW system sustained a minimum of 15%isbondedtothe Determinetheupliftresistancemembrane higher wind uplift resistance than OSW system.adhesives, and of the roofing system in accordancesubstrate using withtherequirementsofCAN/The OSW system develops an asymmetrical forcecomponents be-all the other CSAA123.21,whichistheonly Figure 9. Deck weld failure mode. compliance standard by the NBCC.low the roofing membrane are Figure 9. Deck weld failure mode. by pulling the bottom membrane. The fasteners The U.S. has several wind uplift testintegratedusingadhesives,as fasteners on the seam is called fastenershown in Fig. 5.spacing, fasteners on the seam is called fastener spacing, methods,includingFM4474and January 2025IIBEC Interface13and the spacing between two rows of fasteners and the spacing between two rows of fasteners UL 1896.Q5: What Is the Weakest on the seam is called fastener row spacing. The Step 3: Correlationon the seam is called fastener row spacing. The Link Concept in the recom mended practice is to orient the fastener Select a roofing system and relat-recommended practice is to orient the fastener ed components with uplift resistanceDetermination of Wind rows perpendicular to the steel deck flange, as rows perpendicular to the steel deck flange, as higher than the design load (Fig. 2). Uplift Resistance?shown in Fig. 14.shown in Fig. 14. Wind induces load on the roof. Q3: What Is CSAIt is resisted by each component by Q8: WHAT IS THE ROLE OF A123.21 and How Was Ittheir resistance. This can be illustrat-Q8: WHAT IS THE ROLE OF Developed? ARD?INSULATION/COVER BO through a force resistance link dia-ed INSULATION/COVER BOARD?In addition to the deck and mem brane,respectively for MARS in Fig. gram In addition to the deck and mem brane,in Fig. 7, and AARS in Fig. TheCanadianmodelcode6, PARS insulation is also important substrate/roofing NBCC specifies wind load require-insulation is also important substrate/roofinglinksshallremain Figure 10. Fastener pullout from the steel deck. ments for the design of roof assem- 8.Allresistance Figure 10. Fastener pullout from the steel deck. component in a roofing system. The primary Figure 10. Fastener pullout from the steel deck.component in a roofing system. The primary blies. To comply with the NBCC,connected to ensure the system will function of insulation is to act as a thermal barrierep the roof in place. function of insulation is to act as a thermal barrier the CSA A123.21 standard providesbe durable and kefor the roofing system. The cover board enhances test requirements for resistance eval- Failure occurs when the wind uplift for the roofing system. The cover board enhances the resiliency and durability of the system. It is uation. T d resistance should beforce is greater than the resistance of estethe resiliency and durability of the system. It isof these links. This installed below the me designany one or more equal to or greater thanmbrane and above the the installed below the membrane and above thehelpstochoosethe load. First published in 2004, CSAunderstanding insulation to minimize the deterioration of othercomponentsand insulation to minimize the deterioration of other A123.21 was subsequently revised/ appropriateroof components during the service life of the roof. components during the service life of the roof. edited in 2010 and 2014, with theconstruction techniques at the early Substrate should have sufficient compressiveor by replacing/adding design stage lateste ate sho publishedin2020. Substr ditionuld have sufficient compressive strength and pull-through strength. A weaker The R&D for the standard was de- components to improve wind uplift strength and pull-through strength. A weaker velopedbytheNationalResearchresistance during the reroofing.pull-through strength can cause a cone cut on pull-through strength can cause a cone cut on CouncilCanada(NRC)industry-the substrate board, as shown in Fig. 15. In the the substrate board, as shown in Fig. 15. In the based consortium, Special InterestQ6: What Is the Role of AARS and PARS, the membrane is adhered to AARS and PARS, the membrane is adhered to GroupforDynamicEvaluationofStructural Deck?the top surface of the insulation/cover board. Thestructuralsup-Roofing Systems (SIGDERS).the top surface of the insulation/cover board. The Deckprovides Figure 11.Membranepullout e rom t eh a s i te nerp l ed tei fing syst ch . interface peel strength between the membranehaveadequateff fa in mechanniiccaallllyyaattttaacchheeddrrooooffiinnggssyysstetem.m. Q4: What Are the tthf tep ate n me aFigure 11. 11.ran emb ut from pullou r plate in mec ancallyer ach aro em interface peel strength between the membranemust Figure Memb M e pullo ranethe fasten romhe s n att l o port,andit an strengthandrigiditytosupportr essiisstttthheanddtthheessuubbssttrraatteesshhoouullddbbeeaabblleettoore eDifferent Types of Low- dead and live loads. These loads ei-sheeaarrffoorrcceessccrreeaatteeddffrroommtthheewwiinndduupplliiffttffoorrcceettoo ortensile sh therinducecompressive Slope Membrane Roofing avvooiiddtthheettyyppeessooffffaaiilluurreesssshhoowwnniinnFFiigg1166 acombinationofforces. aSystems? forcesor TheroofingassemblyconsistsSteel, concrete and wood are three Q99: W common deck materials used for the Q : WHHAAT IT IS TS THHE RE ROOLLE OE OF A of a deck and roofing membrane. ItF A may include components such as va- MARS/AARS/PARS. There is a lot VAPPOOR BR BAARRRRIIEER (R (VVBB))??LEADERS IN ROOF VAof research related to the use of steel VACUUM SALES Aaceerrttaiainnrreessiissttaanncceettooaaiirrfflloowwincommercial roof systems. pour barrier or retarders, insulation,in AVVBBooffffeerrss a c decks on Call For A Quote cov dit io n t oit sppriim roofing systemTherefore, this article only focuses ad er board, etc. Thearryyffuunnc tiioonnoofflliimitmitiinng g vvaappoorraddi t i onto i ts r m a c tconsistsofcomponentsabovethe d Thee rrooooffiinnggssyysstteemmffrroommiinnddoooorrss651-398-3029 diiffffuussion ion iinnttootthheis applicable toontheuseofsteeldecksoncom-deck.standard emiroofvacs.com BaasseeddoonnSSIIGGDDEERRSSrreesseeaarrcchh,,ssyysstteemmsswwiinndd However,although B membraneroofingsys- mercialroofs. low-slope uplift fallinoneofthreecat- SIGDERS has limited research data u pliftrreessiissttaanncceeiinnccrreeaasseeddbbyy2255%%tto5500%%ffoorrtemsthatoegories, s s onconcretedeckandwooddeck, sy each of which describes the w th ouutaaVVB,, s ysstteemmswwiitthhaa VVBBtthhaanntthheessyystteemmss wiit h o t BREMY CONSULTING ENGINEERS LTD. way the roof system is secured to theboth deck types are known for hav-Figure 12.ass shhow niinn Fiigg117 T heewwin d uas o w nF 7Th i n dupplliiffttrreessiissttaanncece Figure 12. MMeemmbbrraanneesseeam failuram failureeWindows & Doors deck/structure as indicated below. ing moisture migration issues. RoofingStructural Engineering w The wind uplift induces tensileParking Garages & Balconies waassvvaarriieeddddeeppeennddiinnggoonntthheeaaiirrppeerrmmeeaabbiilliittyy Mechanically Attached Roof- Building EnvelopeMechanical Engineering offtthheeVVBBaannddttyyppeeooffrrooooffiinnggssyysstteemmAAllssoo,,iinno ing System (MARS): a systemforces, which are transmitted to theAsphalt & Concrete PavementsElectrical Engineering the field, poly anddkkrraaffttppaappeerraarreemmoreedeelliiccaatteestructural or pneu-in which the roofing membranedeck through the the field, poly an or dmatic load path or a combination of Two Locations to Serve You - Toronto & Burlington, ON m i rial ter hat tently attached to theooottttrrafffiicc,s in s t mit ay not stand up t o a f ,maatteerialsthat mmay notstand up tooffdeck using fasteners, as shownboth.Therefore,thedeckstensile www.remyeng.com 905-639-1911 maatteerriiaallssbbeeiinnggddrraaggggeeddoovveerrtthheemm (puncture)its attachment to the(puncture) m in Fig. 3. strength and anPartially Attached (hybrid)joistsarecriticalastheycaninflu-a nddtthheeeeffffeeccttssooffhheeaattoorrssoollvveennttsswwhheenntthheerrooooffm membraneRoofingum ence the wind meemmbbranraneeiissaapppplliieedd((asssa su miinnggtthhaatttthheerreeiiss uplift resistance of a System accoonntiinnuouusscoonnneeccttioonn bbeettwweeennttheeVVBB aannddt uo c n i e roof system.a (PARS): a system in which theht heemmeemmbbrraanneeaatttthheeppeerriimmiitteerraannddooppeenniinnggss))th16ONTARIO ROOFING NEWSISSUE 1 2025 Self-adhered mmeemmbbrraanneesswwiitthhaattrriillaammiinnate ateORNSelf-adhered THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIOfacceerr,,ffoorreexxaammppllee,,wwiillllssttaanndduuppttootthheerriiggoorrssoofffaththeessiitteeaaccttiivviittyybbeetttteerrQ1100: W: WHHAAT IT IS TS THHE RE ROOLLE OE OF F Figure 13.QFigure 13. 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