tiling bathroom with 3/4" osb subfloor


Old 08-21-09, 07:28 PM
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tiling bathroom with 3/4" osb subfloor

I am getting ready to tile but I'm concerned that the 3/4" osb wont be strong enough to prevent tiles from cracking. I am still torn between using backer board and ditra membrane, but I'm leaning toward using the ditra because of the added bonus of being a moisture barrier, but if i do that would i need to add to the subfloor? or if I go with the 1/2" cement backer board would i need to add more strength to the subfloor? any help would be greatly appreciated, I really only want to do this once.
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Old 08-21-09, 09:32 PM
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The subfloor meets minimum requirements for either Ditra or cement backer board. Neither Ditra nor cement board will add strength to the subfloor. It is always better to add another layer of underlayment grade plywood if you want to and can without causing height problems. Use minimum 3/8" C/C grade or better. Again, thicker is better.

You didn't mention the type of tiles you're planning to set. Is it glazed ceramic/quarry, porcelain or natural stone? Have you checked the framing to make sure it is adequate for ceramic or stone tiles?

Old 08-21-09, 09:45 PM
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Just opinion but I'd fire any contractor who used OSB as a floor. You really ought be careful of any work he does for you.
Old 08-21-09, 10:56 PM
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I don't disagree, I'd rather see good quality 3/4" ply sub, but 3/4" OSB is widely used and the good brands are pretty good. Advantech comes to mind.
Most of the specialty OSB subfloors are actually stiffer than plywood. The bottom line is the lower price though.

Old 08-22-09, 06:08 AM
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While Advantech is made similarly to OSB, it is specifically made for subflooring. OSB on the other hand is a poor choice for subflooring. Lower price can get you a fuel cell "o" ring that can fail in flight. Sad example, but cost shouldn't be the only consideration when building.

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