I'm looking at putting ceramic tile in the basement but the more I read the more I see that you're supposed to have 2" of XPS insulation foam under the concrete slab. Seeing as my house was built 1959 I don't think I have 2" of XPS there and I can't imagine that it's cost effective to dig up the floor now to put the foam in.
I'd like to not put in one of those systems where you use 3 inches on just subfloor to get the insulation value in but I would like a thermal break so that the floor isn't freezing and if I choose to put heating under the floor that most of the heat will be going to the tile.
So, is there any product out there that I can use as a thermal break? I was hoping there would be something like ditra out there, but most of the products I come across are for floating floors (laminate etc) only. Anyone have any ideas?