Suitable high R-value wall for Zone 2?
I’m designing a small house (710 sq ft) in Phoenix AZ (Zone 2) with the eventual end goal of it being net-zero. Most homes around here are built with 2×4 stud walls filled with fiberglass batts or blown cellulose and that’s about it (and all that’s needed for code). I want to take it a couple steps further.
I’ve attached a proposed mockup of a roughly R-32+ wall. Some notes:
1. The “service cavity” may be filled with insulation if it doesn’t cost much more
2. The 2×6 walls will have whatever makes sense money and build-wise, since all three options are roughly the same r-value.
3. Polyiso on the outside to take advantage of its foil-based radiant barrier as much as anything else.
4. Caulk and tape darn near everywhere, to make the 2×6 part air-tight.
Any criticisms or suggestions to improve with this? As in,
Is something outright wrong or missing here?
Is something about this worthless or at least not worth the cost?
Can this be improved by changing one or more small things?
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