A homeowner asked me the following:
Todd, we are building a home with 8″ structural insulated panels (SIPS) for the roof decking (9/12) and want to use a Fabral SSR roof on top. As an engineer, I know the value of ventilation, but when asked, the roof & SIP manufacturers point at each other and say, ‘whatever he says’. Do I need to spend a fortune to build up a secondary decking system with lathe on top of the SIP for ventilation, or can I slap the metal directly on the SIP (with ice shield)?
Great question. In my experience, if you have a vapor barrier on the bottom side of the SIPs and if the joints between the SIPs are properly splined and sealed to prevent moisture migration, you should be fine.
There are, though, as an option, some SIP panels with built-in ventilation grooves. You could consider those as well.
Todd's expertise comes from his years of experience in metal roofing manufacturing. As president of Classic Products, Inc. based in Piqua Ohio, Todd runs two of the world's leading manufacturers of residential metal roofing. His personal goal is to educate homeowners of the long-life benefits of metal roofing.
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