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I've read that OSB is not suitable as a flooring substrate for tiles. But if the substrate will be cement board, is it ok to use OSB beneath that for subfloor repairs?

jay613
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1 Answers1

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I have used backer on OSB many times.

I like to use thin set to the floor for a rock solid base (OSB pulls the moisture out of the thinset two fast and if kept wet it swells please don’t ask how I know (oops)) with OSB I use mastic it has to dry for 24-48 hours (the brand I used)but adding an additional bonded level makes the floor tougher and less prone to damage.

I was taught to bond the backer to wood flooring and have seen the difference it makes in my own homes (I am a really big guy) I found the tiles if also back buttered much less susceptible to bullseyes when things are dropped on them.

Ed Beal
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