I'm trying to make the best of a bad situation here.

New (old) house + slow drain + airhead teenage daughter = flooded 2nd floor bathroom.

It flooded so bad that the ceiling in my entryway underneath partially collapsed. I was in the process of removing the damaged sheetrock when my wife saw the underside of the floor and asked if we could heat the floors since they were exposed.

We don't have heat in that bathroom (Apparently code doesn't require heat in bathrooms in New Jersey), so it would be nice. But I can't imagine effective radiant heating through tile + subfloor. Is it possible? If so, should I be using a hot water system or electric. I've installed electric systems embedded in mortar but I'b be a bit intimidated about having them exposed to oxygen, and against the subfloor.


I have hydronic radiant heat between the joists under my 2nd story tiled bathroom floor (subfloor + 1/2 CBB + 1/4" marble tile). It works fine. I did staple a kind of radiant barrier about halfway down the joist - basically reflective mylar. Not sure how much that helps, but it was cheap & easy.

  • Interesting, Was it copper or pex? what/where was the heat source? Did you have an independent boiler for this? Gravity fed or did you use a pump? – mreff555 Dec 19 '18 at 20:18
  • Pex - dedicated circuit off a boiler, pumped – CoAstroGeek Dec 20 '18 at 4:37

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