ZIP R-Sheathing Climate Zone 5?
I am considering ZIP R-sheathing for a home in Climate Zone 5. The wall assembly would be a ventilated rainscreen as follows (exterior to interior)
1. Hardie Panel siding
2. 3/4″ furring/airspace
3. ZIP 1.5″ R-sheathing (R6.6 total, 12-16 perms for the OSB, <1.0 perm for the polyiso) 4. 2×6 studs 5. Icynene Low Density (5.5″ thick R-20, 11 perms) 6. 1/2″ gypsum The idea is to create an easy-to-build wall system that is hard to screw up, economical, and maximizes R-value per unit of labor. It seems to me that the dewpoint would occur within the Icynene, and would dry to the interior. The polyiso in the ZIP system would protect the backside of the sheathing, which should be able to dry to the exterior. I am considering dense-packed cellulose in lieu of Icynene, but my sense is that I will ultimately need a spray-foam contractor anyway, so why hire two guys when I can hire one? Thoughts?