b'fasteners on the seam is called fastener spacing, and the spacing between two rows of fasteners on the seam is called fastener row spacing. The recom mended practice is to orient the fastener rows perpendicular to the steel deck flange, as shown in Fig. 14.Q8: WHAT IS THE ROLE OF INSULATION/COVER BOARD?In addition to the deck and membrane, fasteners on the seam is called fastener spacing,insulation is also important substrate/roofing Figure 10. Fastener pullout from the steel deck.and the spacing between two rows of fastenerscomponent in a roofing system. The primary on the seam is called fastener row spacing. Thefunction of insulation is to act as a thermal barrier recom mended practice is to orient the fastenerfor the roofing system. The cover board enhances rows perpendicular to the steel deck flange, asthe resiliency and durability of the system. It is shown in Fig. 14. installed below the membrane and above the insulation to minimize the deterioration of other Q8: WHAT IS THE ROLE OFcomponents during the service life of the roof. Substrate should have sufficient compressive INSULATION/COVER BOARD? strength and pull-through strength. A weaker In addition to the deck and membrane,pull-through strength can cause a cone cut on insulation is also important substrate/roofingthe substrate board, as shown in Fig. 15. In the Figure 10. Fastener pullout from the steel deck. component in a roofing system. The primaryAARS and PARS, the membrane is adhered to function of insulation is to act as a thermal barrierthe top surface of the insulation/cover board. The Figure 11.Membrane pullout from the fastener plate in mechanically attached roofing system. interface peel strength between the membrane for the roofing system. The cover board enhancesand the substrate should be able to resist the the resiliency and durability of the system. It isshear forces created from the wind uplift force to installed below the membrane and above theavoid the types of failures shown in Fig. 16.insulation to minimize the deterioration of other components during the service life of the roof.Q9: WHAT IS THE ROLE OF A Substrate should have sufficient compressiveVAPOR BARRIER (VB)?strength and pull-through strength. A weakerA VB offers a certain resistance to airflow in pull-through strength can cause a cone cut onaddition to its primary function of limiting vapor the substrate board, as shown in Fig. 15. In thediffusion into the roofing system from indoors. AARS and PARS, the membrane is adhered toBased on SIGDERS research, systems wind the top surface of the insulation/cover board. Theuplift resistance increased by 25% to 50% for systems with a VB than the systems without a VB, Figure 11. Membrane pullout from the fastener plate in mechanically attached roofing system. interface peel strength between the membraneas shown in Fig. 17. The wind uplift resistance Figure 12. Membrane seam failure.and the substrate should be able to resist thewas varied depending on the air permeability shear forces created from the wind uplift force toof the VB and type of roofing system. Also, in avoid the types of fail ures shown in Fig. 16. the field, poly and kraft paper are more delicate materials that may not stand up to foot traffic, Q9: WHAT IS THE ROLE OF Amaterials being dragged over them (puncture) VAPOR BARRIER (VB)? and the effects of heat or solvents when the roof A VB offers a certain resistance to airflow inmembrane is applied (assuming that there is a continuous connection between the VB and addition to its primary function of limiting vaporthe membrane at the perimiter and openings).diffusion into the roofing system from indoors.Self-adhered membranes with a tri-laminate Based on SIGDERS research, systems windfacer, for example, will stand up to the rigors of uplift resistance increased by 25% to 50% forthe site activity better.systems with a VB than the systems without a VB, Figure 12. Membrane seam failure. as shown in Fig. 17. The wind uplift resistanceQ10: WHAT IS THE ROLE OF Figure 12. Membrane seam failure. Figure 13. One-side weld versus do-side weld for mechanically attached roofing system. FASTENERS AND PLATES?Figure 13. One-side weld versus doubleuble-side weld for mechanically attached roofing system.was varied depending on the air permeabilityAccessories, fasteners, and plates are used to of the VB and type of roofing system. Also, in a)deckattachmentmethodsQ7: What Is the Role ofare experiencing a single-di rection wind load,deck. The DSW system develops symmetricalsecure either the mem brane or insulation or both the field, poly and kraft paper are more delicateto the structural deck.withjoists Membrane? which will rock the fasteners sideways and causeforces along the horizontal direction; this fat at ue deft rmatio ay not st tee d up to foot traffic,minimizes the rocking action on fastener. Fastener/Deck Engagement: The m ig erials o hat m n at the s an l deck/fastener Welding or fastening to a struc- Commonmembranesareengagementeing ioragged oveue ultimatelncture)The membrane width ranges from 1.83 m tofastener tip and thread design will determine turaljoistarethetwocommonmaterials b locatdns. This fatigr them (puy thermoset,thermoplasticandresults in the fas ener pullout from the steel3.66 m (6 ft to 12 ft).The spacing between twothe fastener pullout resistance (FPR) with tand the effects of heat or solvents when the roof fieldattachmentpractices.TwoMB. The membrane must havemembrane is applied (assuming that there is identical sets (welded versus fas- adequate strength to withstand14IIBEC InterfaceJanuary 2025tened) of MARSs with modifiedthe stress from wind uplift. Thea continuous connection between the VB and bitumen(MB)andthermoplas- physical/mechanicalpropertiesthe membrane at the perimiter and openings).ticmembranewereconstructedof a membrane such as thick- Self-adhered membranes with a tri-laminate and investigated at the Dynamicnessandtensilestrengthvaryfacer, for example, will stand up to the rigors of RoofingFacility(DRF)ofthefromproducttoproductde- the site activity better.NRC.Specimensthatwerein- pending on the chemical com-stalledondecksthatwerefas- position and the reinforcementQ10: WHAT IS THE ROLE OF Figure 13. One-side weld versus do materials. As shown in Fig. 11, tened to the joists performed bet- uble-side weld for mechanically attached roofing system. FASTENERS AND PLATES?terthantheweldedspecimens.themembranewasstretchedAccessories, fasteners, and plates are used to r around the fastener plates, lead-The weldiencthe weakest link, tion wind load,deck. The DSW system develops symmetricalsecure either the mem brane or insulation or both are exper was ing a single-di ecas ing it to pull out from the fas-swhwn will rock the fasteners sideways and causeforces along the horizontal direction; thisto the structural deck.hoich in Fig. 9.b) deck strengths tener plate; this is known as the fatigue deformation at the steel deck/fastenerminimizes the rocking action on fastener. Fastener/Deck Engagement: The cookie cut failure. In this case, Steeldeckstrengthsarede- the membrane was the weakest engagement locations. This fatigue ultimatelyThe membrane width ranges from 1.83 m tofastener tip and thread design will determine termined by the combination of results in the fast ener pullout from the steelthat3.66 m (6 ft to 12 ft).The spacing between twothe fastener pullout resistance (FPR) with the thickness and yield strength.linkforroofingsystem. ThemostcommondecksusedReplacingitwithathicker 14IIBEC Interfaceand/orhighertensilestrengthJanuary 2025in North America are 22 ga andmembrane will help to increase 20 ga with 230 MPa (33 ksi) andthewindupliftresistanceof 550MPa(80ksi).Twoidenti- thesystem.calMARSswiththermoplasticMembrane seam strength is membranes were constructed andan important parameter that in-tested at the DRF of the NRC.fluences wind uplift resistance Thefirstspecimenthatwasin-stalledon22ga,550MPasteelin MARS. The seam must re- INDEPENDENT. deck had a lower sustained pres- sist fluttering and pulling forces due to wind uplift force. Some sureof7.90kPa(165psf)thanmanufacturerssupplymem- UNBIASED. the second system, and the failurebranes with factory seams, but mode was determined to be duemost of the manufacturers re-to the membrane fastener havingquire seaming during construc- COMPREHENSIVE.pulled out from deck, as shown intion. There are three different Fig. 10. The second specimen wastypes of seam application meth-installed on 20 ga, 550 MPa steelods for MARS. Thermoplastic deck and passed a sustained pres- membraneseamsarehotair sure of 8.62 kPa (180 psf). weldedbyaroboticmachine.www.dycon.ca|info@dycon.ca|1.800.749.8609respective deck engagement. Fig. 18 showsRoof Replacement & Project Management & three dif ferent fastener sizes along with the physical characteristics of the head, tip, andWork-In-Progress Quality Asphalt Pavement: Design, thread. Fig.19 shows plotted FPR data for Specifications, Tendering &Assurance Inspectionsfive fasteners with four different types of Contract Administrationdecks. The data shows that the FPR is higher with a greater shank diameter, irrespec tive of Preventative Maintenance the deck types. The data also shows that thePrograms Roof, Building Envelope FPR for two different sources with the same & Pavement Evaluations: fastener type (#15 or #21) measured different values, respectively.Rooftop PV Solar Service Life Assessments, Fastener Plate/Membrane EngagementConsultations &Capital Planning & in a MARS: This engagement keeps theInstallation InspectionsMaintenance Plansmembrane in place. The barbed plates provide a better clamping force compared to smooth ones. The flat, smooth plate allows membrane Thermographic Roof Leak ManagementFigure 14. Membrane fastener rows are perpendicular to the deck flanges. slippage and tearing along the fastener shank,Infrared Analysisas shown in Fig. 20 (left), even at low wind Figure 14. Membrane fastener rows are perpendicular to the deck flanges. uplift pressures. At high wind uplift pressures, the barbed plate bends due to the membrane bill owing and loses its clamping force; the membrane is stretched along the deformed plate ORN THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO portion, which results in the membrane beingONTARIO ROOFING NEWSISSUE 1 202517torn as shown in Fig. 20 (right). If the membrane tensile strength was lower than the wind uplift load, the membrane would stretch and tear Figure 15. Substrate pullout from the fastener and plate for a partially attached (hybrid)around the fastener plates.Fastener Plate/Membrane Engagement membrane roofing system. in a PARS: The membrane is adhered to the top surface of the insulation. The insulation is secured to the deck with fasteners and plates. Based on SIGDERS research, systems with smooth-surface insul ation plates increased the wind uplift resist ance by 50% more than systems with textured insulation plates. Fig. 21 illustrates the failure modes for different insulation plate configurations. Textured hexago nal plates offer the required contact area with the membrane only through the outer and middle rims of the Figure 16. Facer delamination failures for an adhesive applied membrane roofing system. plates. Smooth circular metal and plastic plates have a larger contact surface area to increase the bonding strength with the membrane.Q11: WHAT IS THE ROLE OF ADHESIVE, ADHESIVE AMOUNT, AND CURING TIME?Adhesive curing time is the key factor to deter-mine the adhesive bond strength. The higher the adhesive bond strength, the better the wind uplift resistance. For a scenario tested by SIGDERS, a system failed below 2.87 kPa (60psf) with 14 days of curing time. The system had a wind uplift resistance of 3.59 kPa (75 psf) with 21 days of curing time and a wind uplift resistance of 4.31 kPa (90 psf) with 28 days of curing time. The failure modes for 14, 21, and 28days are adhesive failure between the cap and base sheet interface, a cohesive failure between Figure 17. Wind uplift resistance with different type of vapor barriers. the cap and base sheet interface, and the VB January 2025IIBEC Interface15'