Overpour or not?
I'm preparing to build a super-insulated spec house (R-36, R-60) in far northern Wisconsin. The site has an insulated 28'x40' slab-on-grade already there from a previous owner, and I'm pondering the best way to incorporate in-floor radiant heat into the house. (There is no need to inform me that most energy-interested folks think that in-floor heat is overkill for a super-insulated house.) I just built and sold a similarly-insulated house with a heated slab and no heat source on the second floor, and am looking to do that again.
The two methods I'm considering are these:
1) Put down 4" sleepers for all main-floor walls; put 3/4" XPS around the sleepers; fill in the floor area with 2" of XPS, staple down 1/2" PEX and 2" of concrete. I like this method because it doesn't involve the heating of a monolithic footing because the heated concrete will stop at the inner edge of the exterior wall, and the relatively small amount of mass will minimize the slingshot heat effect my last house suffers from while still enabling me to have a stained concrete floor, which will go well with the industrial/modern interior design.
2) Put down 3" sleepers for all main-floor walls; put 3/4" XPS around the sleepers; fill in the floor area with 2" of XPS and 1" of particle board or other sheet product; route out tracks for the 1/2" PEX in the particle board and cover it all up with some type of engineered flooring. I like this method because it involves heating very little mass, which I assume will make the system more responsive. And because I won't have to pour concrete.
I welcome any thoughts on these or other assemblies. Please keep in mind that I'm not trying to build the absolute most efficient house possible, I'm trying to build something that balances good energy performance with UPFRONT cost and sale-ability.
Posted Sat, 04/26/2014 - 21:12
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