Our 1600 SF basement has a slab floor with no insulation underneath. I'm redoing the bathroom (roughly 100 SF, with 7' along the foundation wall) and would love to put in radiant floor heating, but I don't want the floor to be 2" higher than everything else to allow for insulation over the slab.

I'll be jackhammering out significant portions of the floor to reroute plumbing already. Could I replace the slab in the bathroom with something more conducive to radiant heat (e.g. rigid foam with a framed floor on top), or put down rigid foam and pour a thinner slab on top of it? What problems could these approaches cause?

1 Answer 1


After you remove the floor, dig 2 inches lower for the insulation and pour the new slab to the same thickness as before.

  • Any risks of cutting the middle out of the existing slab? I don't think it's pre-tensioned or anything
    – Drew
    Commented May 15, 2015 at 15:01
  • As long as it's not near any columns or cutting into any foundation footers, it should be fine.
    – Netduke
    Commented May 15, 2015 at 15:22

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