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TOPIC: Installation

Metal shingles over Strapping over ComfortBoard 110.

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Hi

I’m considering a high R roof assembly on a 7:12 roof that consists of ply sheathing over rafters, then 2” of ComfortBoard 110. I would then like to have an air gap to create a cool roof.

Can I then add strapping, without installing another layer of plywood sheathing, to install aluminum shingles. Or will I need to add another layer of plywood sheathing?

Thank you

Simon Body

5/16/2022
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I assume your construction does not have an attic. Your plan sounds good though with attic situations I'd prefer to see more insulation on the attic floor and then a very well vented attic, including a roof with a thermal break of some sort. Aluminum shingles are not to be installed over strapping. That said, the formation of any metal shingle does create a thermal break between the metal and the roof deck and that is always helpful. No, it's not 100% but it is substantial. It also is not actively vented but it's still a thermal break. Many aluminum shingle manufacturers, while not allowing installation over strapping, would probably be comfortable with using an entangled mesh product like Dry-Tech between the underlayment and the metal shingle for even more of a thermal break.

Todd Miller
Todd Miller
Isaiah Industries, Inc.

5/17/2022
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