Floor prep for ceramc tile

Old 01-13-09, 11:56 AM
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Floor prep for ceramc tile

I'm retiling my bathroom floor (the floor previously had porcelain 4x4 tiles covering it) and I'm ready to prep the floor. The subfloor consists of two layers of plywood equaling 1 1/8" so I believe that the floor is thick and sturdy enough to handle the ceramic tile. Can I thinset the tiles directly to the plywood as were the previous porcelain tiles or is it necessary to use hardibacker between the tile and plywood?

The surface of the plywood is pretty flat and smooth...would a layer of self leveler be advised or should I not be concerned with the few small nicks I made while removeing the previous tile? Won't the thinset fill those in?
Old 01-13-09, 12:15 PM
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There is a method for setting tile directly to plywood, however the method calls for minimum subfloor of 5/8" plywood and minimum underlayment of 5/8" plywood totalling 1 1/4". You do not have that, and close isnt good enough. There are other requirements for setting directly to plywood, and if anyone of those is missed or done wrong, it could result in cracked tile and grout. There are better ways.

If your concerns are height, you could use ditra, an isolation membrane thats only 1/8" in thickness over the plywood. You could also use 1/4" cement board over the existing plywood if you prefer.

If all you have is a few small nicks in the plywood, you need not do anything to the plywood.
Old 01-13-09, 01:36 PM
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Yes, in addition to what Johnny said, but the tile over plywood is only suitable for dry areas only. Well "suitable" isn't really right word because it's a very poor way to install tiles on any floor.


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