replying to David Bonnell, Stefan wrote: Although i couldn't tell you what others do, and I'm not proficient in state to state housing code, i can say this all with confidence. I have builded (built)
12 high efficiency houses, 6 in Maine 3 in Minnesota, 1 in Wisconsin, 2 in Missouri. Exterior walls need to be built to the code of the area you are building. Code is by all means a minimum requirement, anything beyond (better) code is good. So start with 2x 10 exterior walls. After framing and siding, before wiring and plumbing, build a second wall inside the exterior wall, running parallel. This interior wall should NOT be structural. Leave a space of 1-3 inches between walls, and at no point should they touch. Plan your exterior size accordingly. Making your basement 10 to 12 inches thick instead of 8 will help immensely. Insulate the excretor wall with the proper sized insulation, and insulate the interrupt wall like wise leaving the couple of inches as a dead air space, which BTW could also be insulated but would only invade the efficiency by a fraction. In doing the roof, follow the same principle, insulated the rafters or trusses, and so the cowling and insulate it also. Plan ahead for your desired ceiling height. I hope this helps you, and if you have questions, i can be emailed through this website.