Floor insulation

We will have radiant floor heating for at least the ground floor and I hope to eventually have it for the second floor too. I'm just working through the calculations for the radiant floor spacing and they are going well.

I prepped the floor with two layers of R 12.5 rigid foam insulation. I'm not sure specifically what type as I just went to the building center and asked for insulation I could lay below a concrete slab. It has a picture of Pink Pather on it ;-)

I also put a layer of 6 mil plastic between the two layers of foam. Most designs seem to lay the plastic on top of the gravel, then one layer of foam. I figure that would perforate the plastic and I knew I would have two layers.


On top of the 2nd layer of foam I put 3 inches of sand, compacted it and it awaits the concrete slab.