Insulating monolithic footings
DH & I are going to install hydronic heat in our new home as part of our sweat equity. We are laying down 2" foam board as insulation below the basement slab. Our builder has specified that we do not put the foam board on top of the monolithic footings. He wants us to put down foil to create a thermal break between the concrete and the stud wall. He was very clear that he did not want us to use foil bubble. He wants something that has no potential of being compressed.
I asked him where to get this foil insulation and he rattled off a couple of places in town. I've called around and they only carry bubble foil or nothing. My F-I-L, who designed and installed radiant heating before he retired, said I should just go to Sam's Club and get a box of their heavy duty foil and put that down.
This would simplify my life incredibly if that would really work to create the thermal break. Is this idea feasible? I don't want to have the inspector come out and laugh his head off and then say "NO" you can't pour the floor today.
If this is the wrong forum please let me know. I looked in the heating forum but they seem to be talking more about the actual systems there.