XPS. Are you pouring on bedrock?

i already did..... 1/2 the pad is on bedrock and the other is on very tightly packed clay/rock mix. no room for r value. i did put down the radiant barrier (white side up)??? as per contractor recomondation but now that i am reading and learning here.....
so, is on bedrock as bad a heat sink as i think it is

shaedog: radiant barrier means different things to different people. How thick was the stuff you put down? "White side up" sounds like it may have been one of the R3-R6 flexible EPS or XPS products (eg. The Barrier: http://www.thebarrier.com/pdf/brochure.pdf) not bubble-pack, not aluminized polyester. If it's one of those, it's doing you considerable good, just not as much as 2" (R10) rigid XPS. If it's 3mm bubble-pack or 0.5mm thick sheet, it wasn't worth the trouble.

yup figured. it was thin with a bubble layer in the middle.
gonna be hard to fix!
when heating the slab it takes a lot of the running energy of my GEO system.

Dana glad to see you understand about the benefits of the Barrier= the flexible XPSInsulation. The new Barrier X5 is 1 1/4 thick yes still flexible enough to come in a roll with our patented self seaming taped edges. Even tho we selll a lot of reflective foil, we are trying to educate people, it DOES NOT belong underground! www.greeninsulationproducts.com