On 30 Sep 2006 04:42:38 -0700, "arw01"
wrote:

Radiant heat shop floor:

Top soil has been removed
very hard base ground (use a breaking bar to be able to dig in it)
3-7" of 3/4" crush gravel

moisture barrier HERE?

2" polystyryene extruded foam insulation

moisture barrier HERE?

concrete reinforcement mesh
1/2" pex heat tubing
4" concrete with plasticizers and fiber reinforcement

Everyone in the businss has a different opinion if it's below the foam
or on the foam.

Concrete engineer says on the foam
radiant installer says below the foam.

I'm not a concrete guy, but I've always seen it below the foam when
others are doing it- when it's used at all, that is. They don't do it
everywhere. Makes more sense to me to have it below the foam- it's
bound to help the foam hold up longer when it's isolated from the
dirt.