Air sealing for unvented cathedral ceiling
I am planning a remodel which will add a cathedral ceiling,and there is already an existing cathedral ceiling in another part of my home. Since much of the roof will already be removed this seems like a good time to correctly insulate and air seal.On this site (thank you Martin et.al.) the outer layer of rigid insulation is taped at the seams. On the BuildingScience site (thank you Joe et.al.) the unvented compact roof shows self-sealing membrane over the structural roof deck for an air barrier. Somewhere else I read the suggestion to use tape on the seams of the structural sheathing. All accomplish the same goal but differ in execution.
My question is which method is preferred and why?
(I’m in climate zone 5 (Denver) with a local snow load design requirement of 30psf. I’m planning on adding at least 2 layers of 2″ of poly-iso above the structural deck and filling the 8″ rafter bays with dense pack cellulose.)
Thank you very much for providing all the great information and answering so many questions!
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