Insulation and hydronic heat on basement slab
I’ve been researching this as a DIYer for a few weeks and this forum has helped me refine my plans. I am reaching the following installation as a final destination. Existing condition is 4-inch uninsulated slab installed per plans in 1974 over a 6 mil polyethelene barrier
6 mil PE or Epoxy paint as vapor barrier (6 mil much cheaper, so if good enough, I really prefer that)
1/2 EPS (some say XPS?) across the entire floor
1×4 as sleepers spaced 12 inches on center (atop rigid foam), anchored with tap cons (or Ramset) into the concrete below
Pex tubing between 1×4 sleepers
Quickcrete or similar on top of pex tub to bring it flush with sleepers, using sleepers as screed.
Durock or Ditra mat
9×38 ceramic tile
1) Will this be solid enough for ceramic tile? That is, are sleepers above rigid foam a good construction technique here?
2) For the sleepers, am I better with 1×4 pine or ripped Advantech plywood?
3) 6 mil PE or epoxy as vapor barrier (noting that building plans report a barrier but not insulation beneath slab)?
4) Any downside to laying 6 mil barrier atop slab even if there is one (albeit 45 years old) beneath the slab?
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