Insulation for Radiant Heat

Cheeze-Tech

I loaned out my Dan H. radiant book and can't remember his recommendations for insulation under cement floors and around the perimeter. I seem to remember 1" styro and 2" styro, but I can't remember which goes around and which goes under. Anyone using insultarp? Any thoughts about that or similar products?

Thanks!

Constantin

I'd pass on the insultarp...

.... but then again, I'm a mere picky homeowner. I don't see how insultarp can work as well as some of the other options (XPS in particular) when it comes to retarding the flow of conductive heat loss, which I imagine is the primary means of losing heat below ground.

XPS is dirt simple, does not absorb water, and can be had with borates built in to prevent insect infestation. If you want to reap max. benefits, don't just insulate under the slab, insulate the entire exterior foundation wall, as above-ground walls are usually where you'll lose most of your energy. Building Science Corp has excellent printed builders guides on the subject. Their web-site is chock-a-block full of free info as well.