Ceramic Floor Tile

Old 10-25-05, 12:10 PM
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Ceramic Floor Tile

I read somewhere that when installing ceramic floor tile, the subfloor plywood should be prime painted before applying thinset for the cement board. Apparently the thinset doesn't adhere well to bare wood.

Is prime painting a good idea?

Also, should the thinset for the cement board be modified or unmodified?
Old 10-26-05, 05:37 AM
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Technically, you shouldn't use plywood at all for a tile substrate.
(love that tile lingo)
All the experts here will vote that you thinset and screw down a 1/4" cementous material like wonderboard or durock.

However, I've read that you CAN adhere directly to plywood if your floor is sturdy enough and you use the primo thinset, or the stuff you only add latex additive to. I've not heard anyone recommend priming.

Now I read your post again, and you are talking about cement board.

So, AFAIK, use the unmodified thinset under the cement board, screw, and use modified to set the tile.

Hope this helps.
Old 10-26-05, 11:32 AM
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Don't worry about priming, the thinset under the CBU panels is only there to fill anv voids between the CBU and the wood below, not to bond them together.

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