Huber just added more information about their fairly new R-sheathing to their web-site on a couple of tabs to the right of the web page ... http://www.zipsystem.com/zip-system/rsheat.aspx . I would have attached them, but the only item that would fit due to file size is their ESR report (attached) In zone 5, the minimum R-value of exterior rigid foam for 2x4 construction is R-5 and R-7.5 for 2x6 construction. If this R-6.6 product were used with 2x6 wall construction, would there be condensation concerns within the wall cavity? Plan would be as follows from the outside in: - Fiber cement cladding - Zip R-6.6 sheathing - 2x6 walls at 16"OC - BIB fiberglass as part of Owens Corning's Energy Complete air sealing system (R-24) - 1/2" drywall - Latex wall paint The wall would have to dry towards the interior with the 1" of polyiso that's part of the zip R product. But is that 6.6 not enough in zone 5 for 2x6 construction? Does it only satisfy 2x4 construction in this climate to avoid condensation issues within the wall cavity? Your comments are appreciated ... thanks.