I'm going to use Prova-Flor + 5/8 T&G OSB + Laminate flooring planks for flooring in my basement, so the total height should be around 1 1/2". I'm not sure what to do about the bathroom, though.

I could use Ditra membrane + ceramic tiles directly over concrete, which is relatively straight-forward, but I'm concerned that:

  1. The floor will be very cold, especially during the winter.
  2. The floor in the bathroom will be much lower than in other rooms.

Products like Prova-Flor do not list ceramic tiles as supported top floor, so I'd like to know what could I use to try to insulate the top ceramic tile layer from the cold concrete beneath it. I don't want to actively heat the floor, though.

  • You could use the 3/4" CDX plywood with Ditra on top, then tile? The height should come out about the same. Aug 29, 2016 at 0:39
  • Is it OK to put the CDX plywood on bare concrete, or should I add a vapor barrier under it?
    – haimg
    Aug 29, 2016 at 1:57

2 Answers 2


A different solution would be to build up the height with cement board, and use vinyl instead of ceramic to make the floor feel warmer. (It's not actually warmer, it just draws less heat out of your feet so it feels warmer and also feels a bit softer.)

There are vinyl tiles and planks that would look (almost) as good as ceramic, or that would look a lot like your laminate flooring outside the bathroom.

If you use cement board directly on the concrete you don't need a waterproof membrane above it. You can use the breathing subfloor membrane underneath if you want, so the cement board and bottom side of the vinyl will not be damp.

  • "I don't want to actively heat the floor" - then, no. Electric floor heat in the bathroom, or stop complaining. Or don't use stone, +1
    – Mazura
    Sep 16 at 16:40

I just got a water leak in my basement, so wouldn't put anything that can have mildew.

So I would install a rubber membrane about 1/8" made of recycled tire that insulate from cold fairly good for the thickness, and it cut the humidity, just tape the joint with tuck tape underneath.

For the bathroom with the money you save with the plywood not installed put Schluter Ditra™ heat membrane and heat the floor, great when you come out of the shower.

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