It may be helpful to distinguish between exposed-fastener metal roofs and other roofing systems.
If you’re working on a metal roof that is attached with exposed fasteners, I don’t know of any practical solution for retrofitting PV without adding more exposed fasteners. And, yes, the mastic under the L-foot will likely outlast the waterproofing around the roof attachments. However, according to conversations I’ve had with James Kirby, exposed fastener metal roofs are not an NRCA-approved/recognized roofing system. The waterproofing methods on exposed-fastener metal roofs are inherently inconsistent with NRCA standards. Other roofing systems are consistent with NRCA standards. If you don’t use flashing with these NRCA-approved roofing systems, your PV attachment method is going to compromise the waterproofing for the roof system. You can’t really argue that point, because there are established standards that apply to flashing and waterproofing according to roof type. David Brearley Senior Technical Editor, SolarPro NABCEP Certified PV Installation Professional david.brear...@solarprofessional.com Direct: 541.261.6545 Follow us on Twitter: @SolarPro Check out this AMAZING music video tribute to SolarPro: http://bit.ly/1qfMCCh
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