What is the proper window detail for the “Perfect Wall” system?
I am building in Kansas City, MO and plan to use the “Perfect Wall” concept of 2×6 walls with Icynene and 1.5″ of rigid foam on the exterior. I have not seen agreement on how to handle the window and door flashings. For instance, should the window flanges go over the foam at the window openings or should you line the window openings with a 2×4 so the window can be mounted into a solid piece of wood? This would provide a more stable connection, but negates the benefit of the thermal bridging provided by the foam. Secondly, should the building wrap go on the exterior or interior side of the foam? How should it be connected right at the window? I am leaning towards using Zip Wall sheathing (which I wouldn’t normally use solely as the building wrap because I believe physics beats chemistry – overlap is better than tape) under the foam and then building wrap over the foam. I know it is a bit overkill, but each system by itself seems to be inadequate.
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