Exterior foam substitute above thermal envelope on attic wall
ranson
| Posted in Green Building Techniques on
Hi,
I’m planning 4″ of exterior rigid foam on my walls with a cellulose insulated attic floor. My WRB is outside my rigid foam. Because design uses a monoslope roof, there’s a large portion of attic wall that’s above the thermal envelope of the house. In this area, are there any good assemblies that I can substitute for the rigid foam? My hope would be to reduce labor and use less foam.
–John
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Replies
John,
The answer depends in part on your siding choice, and whether or not you intend to install vertical furring strips.
If you are installing 1/2" plywood furring strips over your 4 inches of rigid foam, you could, in theory, install three layers of 2x4s as furring strips on your attic wall. That makes the furring strips co-planar.
To me, this approach is costly, fussy, and not worth the trouble. I would just install 4 inches of rigid foam over everything. If you want to save money, buy recycled (reclaimed) rigid foam.