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jpl80 02-05-2009 07:47 PM

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I want tile in my bathroom. Under the linoleum, there is 5/8" particle board subfloor and 3/8" plywood underlayment.

The joists are 9"x2" about 15" apart.

Will 1/4" backerboard on top be enough? Also, can I leave the linoleum down and just install the backerboard/tile over the top of it? I had a guy tell me that it acts as a vapor barrier.

JazMan 02-06-2009 09:26 PM

Did you mean to say that under the sheet vinyl is 3/8" underlayment and the subfloor is 5/8" particleboard? If so, you have a problem. According to all standards you need to remove the particleboard and start from scratch with a new subfloor.

You should find a tile setter that knows his stuff.


jpl80 02-07-2009 07:38 AM

Thanks for the reply. I'm getting quotes from several tile professionals and none of them have mentioned that my subfloor was inadequate. Can you tell me which standard you're referring to?

As far as the particleboard... It looks like particleboard to me, but I'm not a carpenter...

Thanks again for the advice...

jpl80 02-08-2009 08:00 AM

I think it's OSB and not particle board.

so 5/8" OSB with 3/8" plywood on top.

Should I be okay with 1/4" backerboard on top of that?

JazMan 02-08-2009 07:11 PM

Well OK, it makes a big difference whether it's PB or OSB. OSB would be acceptable, but NOT it it's only 5/8" thick. Please check again, it should be 3/4" t&g subfloor grade. The stampings can be read from below. It might say 23/32" thick.

In your last post you didn't mention the sheet vinyl at all. We need to start from the beginning.

I'll assume your joists are 2x10" which measure 1.5x9.25" is this right? They are spaced 16" on center? All that info is fine but we also need to know the unsupported span of the joists, and if possible the species and grade too. Then when you confirm that the type and thicknes of the subfloor we can help better.


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