Rigid foam exterior, spray foam interior rot problems?
My friend is building a small house in Vermont. He has framed 2x4 walls with exterior plywood sheathing and 1" of blue board outside of that. The facade will be stone with an air space behind of 1". He is planning on using spray foam to fill in the stud bays. I am more familiar with building materials than he is, and this plan struck me as questionable. Will there be rot problems with the sheathing in between the two foam layers? Should he use open or closed cell foam or a different material all together? He needs the R value of closed cell, but open cell has the ability to dry.
He is also planning on using spray foam in between 2x10 rafters for his unvented cathedral ceilings. Any thought?
Another question I have is about the stone. There is going to be one exterior wall that spans into the interior. This creates a thermal bridging issue. Is there a way to isolate the exterior stone from the interior stone in the same wall without compromising structurally? The interior stone is load bearing. Any comments are much appreciated.
Posted Thu, 12/05/2013 - 17:42
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