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Old 09-12-16, 03:00 AM   #5
DEnd
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Join Date: Nov 2011
Location: NC
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The Double stud wall is the cheapest to build but I don't think it is the best wall. if you are ok with foam, you may be able to find used foam insulation for cheap enough that a double stud wall may not make sense, especially if you are the labor supply. There is also adding foam strips to the interior of the studs with a 1x on the interior side for a nailing strip. This can add a bit more cavity depth and also reduce thermal bridging.

As far as sub slab insulation is concerned my inclination is to say either that or perimeter insulation is a good idea. however I would hire Energy Vanguard or some other firm (Allison Bailes at energy vanguard can probably recommend someone if they can't do it) to do some energy modeling and cost optimization. Now is the time to start that conversation as they can help you avoid design issues that can cause large energy penalties.

As for GTHP, I'm meh on them. great concept, not so great execution. The other issue I see judging at least by the ingrams site is that they really don't have something small enough for your situation. I'm betting if you build your house well you will see an AC load of around 1 ton. Heck even finding conventional equipment that small can be a challenge. The majority of your heating and cooling hours will be at part load conditions, this is the area that mini-splits excel at, and where they beat GTHPs.

Quote:
Originally Posted by natethebrown View Post
I would highly recommend you go with non-wood SIPs (Structurally Insulated Panels). May cost more for the materials but time, ease, and insulation value is not beatable.
Not for a first time DIYer. If he can find a contractor with experience with them then they can be a viable option. The SIPs supplier may be able to recommend someone.
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