Return to Installation
Return to Forum
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?
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.
If you would like to reply to this thread, please
If you do not have an Ask the Experts forum user account,