# Sealing a bathroom subfloor?



## CollegeGirl (Jul 21, 2009)

I recently bought my first house. The house is 14 years old and the inspection revealed a leak under a bathtub. I had a plumber come out to repair the leak and he said under the house looked great, no water damage. Tonight I started on a project to lay down vinyl tiles over the existing hideous tiles. I got more than I bargained for. :huh:

The existing tiles were done poorly and evidently in a hurry to hide a layer of warped and stained linoleum underneath. I ripped out the two existing layers to find that the subfloor behind my toilet and near the tub is black with mold and crumbling. It looks like there are two layers of plywood. The top layer is shot, but the layer underneath looks okay.I have a friend who will help me replace the subfloor, but I'm worried about the new subfloor getting damaged. I'm confident that the leak is fixed, but it's a bathroom and inevitably water will splash out of the tub and there will be lots of humidity. Is there a way to seal the subfloor before I lay down the vinyl tiles? Would using a bathroom and kitchen caulk around the tub and toilet be enough? What about between the tiles? I hate to do all this work, just to have to redo it again in a few years. One more question, would it be worth it to file a claim on my homeowners insurance?

Any help would be greatly appreciated...


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## Bud Cline (Mar 12, 2006)

Did you partake in a *HOW* when you bought your home? (*Home Owner Warranty*.) If so... it will cover the cost of a lying dishonest unethical home seller.

The individual tiles you propose to use are not the best floor covering for a bathroom especially if they are the low-cost low-grade peel and stick tiles. Stay away from them. You would be much better off using a sheet vinyl product or ceramic tile.

When replacing the subfloor don't buy the cheapest plywood you can find. Use a plywood that is rated for flooring underlayment and is labeled "exterior grade". This is not to be confused with "treated" plywood. Don't use treated plywood.

The subfloor does not need to be sealed if you use the above suggested products. There is no feasible way to seal the floor in preparation for vinyl tiles.

It is worth mentioning that what is there now may be particalboard. It's hard to say for sure from the pictures but it looks like it is. DO NOT use particalboard on a bathroom floor, ever.


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## CollegeGirl (Jul 21, 2009)

Unfortunately I don't have a home owner warranty. The house was a foreclosure, but talking with the neighbors it sounds like the guy who lived here before did try a couple quick patches to make the home more appealing to sale so it wouldn't foreclose.

I do have the peel-n-stick tiles. I know that they aren't permanent, I was just hoping for something aesthetically pleasing that would work for about a year until I redo most of the floors. Are they so bad that I should just go buy something else right away?

Thank you so much for the advice, I was feeling a little lost.


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## joan smith (Jul 15, 2009)

I think I saw treated OSB board at the home improvement, might be worth it in high moisture areas such as bath.


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## Bud Cline (Mar 12, 2006)

Yes there is "treated OSB" but that isn't intended to be an underlayment. *IT ISN'T SMOOTH ENOUGH* for those tiles and they won't stay stuck.

OSB is a subfloor panel NOT a flooring underlayment.

The correct product is the one I already listed above.


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