New build/wall question
I’m trying to build a fairly simple 2k sq ft 3 Bdr rectangular ranch in Southeastern WI, zone 6. My main concern is energy efficiency. I’ve spoken to 7 builders up to this point, and what I’ve been told is:
1) A 2×6 wall meets code and that’s what we do.
2) We will fill it with foam (doesn’t specify open or closed cell) if you want.
3) Have never seen or heard of foam insulation outside the sheathing. Discussing how it’s done, they state it sounds very labor intensive and they either won’t do it or charge a ridiculous amount to try.
If a builder will build the way they normally will (2×6 with fiberglass), I can build this ranch for 250k. If I say in addition I would like Huber zip sheathing, Roxul mineral wool instead of fiberglass between the studs and exterior foam insulation, it’s 450k – 550k for the same ranch. My rough math shows me a material cost difference of about 15k (certainly there would be additional labor costs, particularly for the external foam).
My first question: is this normal (200k difference for those 3 items)?
In trying a third alternative, I’m talking to a builder about doing some of the work myself, and trying to choose products that I’m hoping would reduce the learning curve for them. They will try using Huber Zip for the sheathing, I’ll be happy to do the taping/sealing. As external foam insulation, rain screen, furring strips than siding is completely foreign to everyone I’ve talked to so far, I thought the insofast with the rain screen and studs integrated so the siding could attach directly would make this appear less daunting with a single step; it’s still questionable if I can convince them to use it. That brings me to my second question:
What wall you would choose given the following four choices:
1) 2×6 filled with Roxul bats, Huber zip then siding
2) 2×6 with blown-in fiberglass, Huber zip then siding
3) 2×4 with Roxul bats, Huber zip, insofast 2.5 inch then siding ( R10 for the insofast foam )
4) 2×6 with Roxul bats, Huber zip, insofast 2.5 inch then siding ( R10 falls short of the 11.25 for a 2×6 wall; how much riskier is this )
I greatly appreciate any suggestions regarding a different approach, product, or other feedback. This is really becoming a frustrating process, more so than I would think, but I haven’t built a home before.
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