Additional insulation below laminated/floating floor over rigid-foam-insulated concrete slab?
I have a 4″ concrete slab insulated with 4″ of rigid foam (on the underside, of course). I was planning to install laminated floating floor on top of everything. As I have to install 2×2″s over the concrete in order to hold the laminated floor, a friend suggested to fill the space between the 2×2″s with insulation or, at least, dirt.
The questions are:
1. Does it really make an energy performance difference (ignoring the “feel” of the floor), to have a ceramic/stone/tile floor over the insulated concrete slab, rather than a floating floor? Just in the areas where I get direct sunlight?
2. In the areas where I will install floating floor for sure (i.e. where I get no direct sunlight), should I install insulation in-between the 2×2″s? Wouldn’t that insulation insulate me from the EPS insulated thermal mass of the concrete slab, which I hope will affect the house with its thermal inertia? Or should I add mud or dirt between the 2×2″s? In that case I wouldn’t be insulating, just adding some thermal mass which will help the heat conduction between the concrete slab and the floating floor. Does that make sense?
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