Wrong underlyment under roof

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Wrong underlyment under roof

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Thanks for choosing metal.

As to the underlayment, I really do not know. Synthetics are used regularly beneath metal roofs. I'd suggest that only Owens Corning can answer your question.

Todd Miller
2019-04-22 08:48:35.364072

I just finished about 20 squares of exposed fastener roofing on my sip panel build and while I started with felt, it got blown off halfway through so I switched to Owen Corning pro armor.

Just noticed it says “for asphalt shingles only”, but I can’t tell the difference between it and other synthetic underlayment meant for metal roofs. So why isn’t it recommended for metal?

I’ve grown nervous about condensation problems on sip panels so I’m likely to insert some 1x4 purlins underneath next year and replace the underlayment while I’m at it, but ... what’s the harm/risk with the wrong underlayment in the meantime?

Theodore Van Rooy
2019-04-22 04:25:35.876585