Advice needed: Tiling over concrete slab [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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09-19-2011, 02:30 PM
Hello all, I am in the process of converting a three season sunporch to a four season. It is a 10x11 room over a concrete slab (no crawlspace). I am using a 30x60 cm tile and wanted to do heat under the tile.

I want to install under tile heat but have been told that thinsetting the heating cables or pad over the concrete slab will ultimately not be efficient as I will lose heat to the slab (I live in Minneapolis and it gets darn cold here). So the recommendation is to thinset foam to the floor and then thinset the heat to that and then the tile. Are there other subfloor options?? What are your thoughts on tiling over foam?

Your advice and thoughts are greatly appreciated!!

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Tiger Mountain Tile Inc
09-19-2011, 10:29 PM
I think the foam (cork?) works for insulation. You might also want to look into the RPM pads. They may also do what you want.

Link is at the bottom of the page.

09-19-2011, 10:43 PM
So the recommendation is to thinset foam to the floor Whose recommendation?
There are only two "foams" possibly suitable for this purpose: Wedi board and Schluter Kerdiboard. Check each mfr's info to be sure.
While you're planning "floor heat", be aware that (so far as I've seen) NONE of the electric floor-heating systems for embedment under tile are suitable as the PRIMARY heat in any place, only as "secondary" that means additional or auxiliary heat. You probably will actually want "real" heat in that Mpls area sunroom.

09-19-2011, 10:44 PM
Welcome Stephanie. :)

Might consider Wedi boards as well.

And in-floor electric radiant heat can be a primary heat source, but it'll be expensive and there's better and cheaper ways to heat a room. :)

Tiger Mountain Tile Inc
09-19-2011, 10:50 PM
I thought I saw somewhere that if you spaced the wire 2" apart that it could be used as the main heat source. The problem is I can't find where I read that.