Rigid foam on inside of wall?
I am working on a Habitat for Humanity SF home where we are trying to meet the thermal bridging requirement of the new ENERGY STAR version 3 the most cost effective way possible.
The cheapest way to meet the requirement is by doing advanced framing, but we may not be able to do advance framing because the house is within 1 mile of the ocean, in the 110 mph wind zone, and the building inspectors are giving us mixed signals whether they will allow it.
Another way to meet the requirement is to use at least R-5 insulated sheathing (we are in climate zone 5 – Massachusetts). It would be cheaper and easier to install the rigid foam on the inside of the wall, behind the drywall, because we wouldn’t need to install furring strips. It would also look better because the vinyl siding wouldn’t be wavy between the strips.
I have come across several builders doing this in New England and they have been happy with the results, but I talked to another person who said it may cause moisture issues.
Would you recommend installing the rigid foam on the inside of the wall? Could it lead to moisture problems?
We want to build a durable home, so any advice you have would be appreciated. Thanks.
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