The Guide offers innovative wall designs— all made with common building materials—that achieve high-performance walls. One drawing (page 11) tallies the contributing R-values of siding, 7/16″ minimum wood structural panels, R-19 insulation, and 5 ½” framing/headers, plus the drywall to achieve a remarkable 0.060 U-factor. In this case, the headers can be engineered wood or lumber. The corners can be two- or three-stud configurations that allow for maximized insulation. But there’s no need to batten insulation of any kind on the outside of the sheathing, or for additional wall bracing expenses. Kositzky claims that the R-19 insulation can be significantly cheaper than high-density batts that would be required if optimum framing techniques were not used.
During our interview, I challenged Kositzky to answer this theoretical question from a builder using 2x4s: “Why would I pay more for 2x6s? I’m putting up 165 starts and the higher costs will crimp my profit.”
“I’d say to that builder: Provide us with your numbers, because your assumptions are probably wrong on the net cost of the 2×4 wall,” Kositzky said. “We’ll do a cost evaluation for that builder, and in most cases, we can show that 2×6 optimized framing options are the cheapest way to go when achieving IECC compliance.”