b'ELECTRICAL CODEFigure 4: An example of electrical installations that must be avoided.(RCABC Roofing Practices Manual)Rule12-022assumesacorrugatedLegally Separated be separated. The RCABCs Guarantee steelroofdeckanddoesnotcontem- Roofing screws must penetrate throughStandardsrequireaverticalseparation plateorganicwooddeckswhichnowsteel decks by at least 19 mm (3/4) andspace of at least 38.1 mm (1-1.5) deep. arecomingintovogueinOntarioandmustpenetrateintoorthroughwoodThatwillallowforadequatefastener Alberta. Furthermore, Rule 12-022 doesdecksbyatleast25mm(oneinch,penetration and also accommodate vari-notcontemplateroofsystemrenewal.nominal).Thisisrequiredbyscrewation in screw length.While a stronger rule would clearly sepa- manufacturerstoensuremaximumDesignersshouldbeawareofthe rate every type of electrical system frompull-out resistance. The operative wordscience behind resistive heating and fires the roof assembly, critics of that positionisthrough,whichismeasuredfromand should specify a separation between argue that the lifespan of a roof does notthe underside of the deck. abuildingselectricalsystemandthe concern the CE Code and that it is uproof. Owners clearly have a stake in the to others to exercise due diligence whenOften, electricians affix conduit andissue. No one wants their asset vaporized and if a roof has to be replaced using junction boxes directly beneath a roofby a non-detectible high-resistance fault. screw fasteners. deck.Canyouspottheproblem?OfInstructing your designer to provide for Although Rule 12-022 appears to ignorecoursethe roof assembly and electricala separation space means peace of mind the consequences of fastener contact withsystems each have good things to offerfor the serviceable life of the building.bythemselves,buttheymaketerrible energized conductors, and lacks the ambi- marriage partners together. 13 Roofing contractors also have a role tion behind related changes to the NECtoplay.Aseparationspacemakesa in the U.S., there are some ways designers,Since fasteners that contact energizeddifference only when screws are suitably owners and roofing contractors can stepelectrical conductors can produce resis-up now to design and build safer buildingstiveheating,andresistiveheatingcan13Assembly refers to the roof system in combina- for the future. eventuallyproduceafire,theyshouldtion with the structural deck that supports it.34 lROOFINGBClFALL 2022'