Underlayment under exterior foam on new roof
Building new home unvented cathedral ceilings Zone 6
Wondering if I need any type of underlayment on my first layer of plywood or if 2 layers of 2.5″ polyiso insulation 1/2 sheathing with peel and stick is fine?
From inside to out Drywall, 11 7/8 I joist with fiberglass batts, 1/2 ” OSB, 2 layers of 2.5” polyiso insulation, 1/2 sheathing with peel n stick membrane, metal roof.
Thanks for any help
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