Does this roof assembly work?
I am building a house in upstate NY. I am about to finish framing and have begun to doubt my unvented roof design. Specifically whether I need to add a path for drying the layer of plywood that will be beneath my metal roofing. This is the sequence from the bottom up: 2 x12 rafters filled with cellulose, layer of 5/8″ ply, 3″ of polyiso foam board, 5/8″ ply completely covered with ice and water membrane, metal roofing. It is a pitch of 1″ per foot.
Should there be an air space between the foam and the ply above? My air barrier was to be the ice and water membrane!
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