Ceramic tiles over rigid foam
kingfisher224
| Posted in General Questions on
I have a large room with concrete slab floor and would like to insulate it and place finished flooring materials over it. I believe 1/2″ plywood over the 1″ rigid foam will support hardwood flooring. However there is a portion at the entryway that I would like to cover with ceramic tiles. Is the 1/2″ adequate underlay going to be sufficient? if not what can I use to insulate plus finish this portion with ceramic tiles and match the height of the (1″ foam, 1/2″ plywood and 3/4″ solid hardwood flooring?)
Is there still available a flexible cement that bonds the tiles to the plywood (Panlastic?)
Please help kingfisher224
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Replies
I would consider going to 3/4 or two layers 1/2" if you're going to use a full 3/4" natural hardwood floor. Consider sealing the floor WELL before installing your rigid foam.
How big of an area? You could put down something like kerdi-board to serve as both insulation and tiling surface. I'm not sure what the pricing will look like.
--John
Here's a link from BSC. They recommend 1.5" foam with building wrap on top of the foam and then T&G subflooring (no thickness indicated) on top of the building wrap.
Notice how the T&G subflooring is sandwiched as it moves from the outer wall and through various load bearing walls.
You can also use liquid gypsum floor leveling system on top of the foam for tiled sections.
https://buildingscience.com/documents/insights/bsi-059-slab-happy
Like John mentioned above - Kerdi is an option. They have all of the details on their website for each subfloor type. I think it is about $4/SF.
I contacted Schluter about using Kerdi-board to insulate a concrete slab under the tile, and their response was "Kerdi Board is not recommended as a floor substrate", nor can I find any details on the use of kerdi as a floor substrate on their site; only walls, counter tops, shelves, etc. Does anyone have any experience with kerdi as a floor substrate?