Closed-cell spray foam under fiberglass for high R-value roof assembly?
I was talking to a spray foam contractor and I was unfamiliar with his method. He applies 2″ of closed cell spray foam to the backside of the drywall on the ceiling and then covers the spray foam with blown-in fiberglass to reach a High R-value. The space is still vented.
Would this approach have concerns or issues? It is not one of the High-R roof assemblies I have heard of before and I can’t seem to find any articles discussing this particular approach.
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