XPS or EPS Foam on the outside of SIP
We are considering adding a layer of either XPS or EPS foam on the outside of a SIP panel house. This allows us to break the thermal bridges resulted from the wood around windows and the corners where SIPs join. Also it adds a little more R-value to our structure.
The question is about the vapor layer. One of the potential wall assembly from inside to outside is Gypsum, SIP, XPS, Furring, then cement siding. The thought is to use the XPS as insulation as well as a vapor barrier.
Another possible assembly is Gypsum, SIP, EPS, House wrap, furring, then cement siding.
Which one would you do?
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