b'Energy LossesFASTENER COMPENSATION FACTOR %DESIGN EFFECTIVE Fastener Density/m2R-VALUE2.69 4.04 6.7326 5.04 7.43 12.4531 6.23 9.21 15.3536 8.01 12.01 20.09Figure 7: Fastener location (example of R-26 polyiso layout).Table 4: Fastener compensation factors - the additional thermal resistance required to compensate for the thermal bridging losses caused by fastener density.Fastenercompensationfac- insulationboardorthecovertion. The testing was conducted tors have been developed to iden- board,iftheassemblyhasonewith #14 fasteners, maintaining a tify the additional thermal resis- in its layout. Within PARS, therefastener density of 2.69/m 2(0.25/tance required to compensate foralso exists roof designs where theft. 2 ). The B-Invt testing was con-the thermal bridging losses. Thesebottominsulationlayerintheducted to quantify how much im-factors were generated from fur- multilayerinsulationlayoutispact the thermal resistance of the ther data analysis of fastener im- mechanically fastened, while thetopinsulationlayerhasonthe pactfactorcurvesandvalidatedtop insulation is attached with ad- overallthermalbridgingeffects throughexperimentaltesting.hesives. To quantify the effect ofwith fasteners installed in the bot-Table 4 provides the offset valuesfastener location in a multilayertom insulation.in terms of fastener compensationinsulation layout, three configu- Figure 8 shows the effect of fas-factors, which is the required per- rations were evaluated in each de- tener location in a two-layer insu-centage increase in the design ef- sign category: lation layout. The data representFigure 8: Effect of fastener location in the roofing system. fective R-Value of the roof assem- Top through fastenersfas- the percentage decrease in effec-bly to compensate for the thermalteners installed on the toptive R-value relative to the assem-bridging losses. For example, theof a cover board bly without fasteners in each de-effective R-value of an R-31 roofBottom fastenersfastenerssign category and each insulation assembly designed with a fastenerinstalled on top of the bot- type.Thelocationoffasteners density of 6.73/m 2(0.63/ft. 2 ) musttom layer withinthemultilayerinsulation beincreasedby15.35percent,Bottominvertedfastenersarrangement has a significant im-around R-36, to meet a target de- (B-Invt)similartobot- pact on the overall thermal per-sign value of R-31. tomconfiguration,butformance of the roofing system. withboardsswapped(i.e.,In the two-layer insulation layout, top and bottom insulation Impact of Fastener Location boards were exchanged) installing fasteners on the secondFigure 9: Penetration depth.layerminimizedthethermal In MARS and PARS, the fas- Figure 7 gives an example lay- bridging effects by 30 to 50 per teners are installed on top of theoutofR-26polyisoconfigura- cent compared to through fasten-ers (i.e., fasteners installed on the top layer). These results represent the scenario where the top insu-lation layer has a lower thermal BUILD MORE resistance relative to the bottom layer.Switchingtheinsulation WITH BEACON layout (i.e., thicker insulation on the top) minimized the thermal bridging from 40 to 70 per cent, depending on the thermal resis-SERVING ROOFING CONTRACTORS ACROSS ONTARIO| CAMBRIDGE| CONCORD | LONDON| OTTAWA | WHITBY tance of the top insulation layer. In a multilayer insulation layout, WWW.BEACON-CANADA.COMthe thermal resistance of the top insulationlayerplaysasignifi-cant role in shielding the thermalFigure 10: Effect of fastener penetration depth.bridging effects from the fasteners installed in the bottom layer.Serving Southwestern Ontario Since 1972 Impact of Fastener Penetration Depth Commercial In commercial roofing instal- Industrial lations,whenusingmechanicalMaintenance Specialists fasteners as a mode of roof attach-Free Estimates / Inspection ment, the standard practice is to 152 Thames Rd. W., Exeter, Ont. N0M 1S3maintain a penetration length of Tel: (519) 235-2802Fax: (519) 235-1532 19 to 25 mm ( to 1 in.) below Email: speat@hay.net the male flute or upper flange ofFigure 11: Fastener area.24ONTARIO ROOFING NEWSISSUE 1 2020 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'