# wood treatment for damp particle board



## mzimmers (Sep 6, 2007)

Hi, all -

I realize this isn't exactly a woodworking question (though it may become one!), but I thought I'd ask the braintrust here.

The subfloor under my kitchen sink has had some moisture on it for a sustained period. (The shelf above it, which I've torn out, allowed some sink leaks to pass through.) The particle board doesn't appear to have separated (yet), so I'm hopeful that I don't need to replace it, but it has swollen a little, and begun to lift. This probably doesn't matter, since I'm going to replace the shelf above it, so it won't show, but…I'd like to put something on it to protect it in the future.

Is COPPER-GREEN a good choice for this? Or if not, what might be better?

Thanks. If you think I need to go a different route here, please feel free to say so.


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## cjwillie (Sep 6, 2011)

Once particle board gets wet and swells, it's history. It will fall apart. Other than replacing it, there's not much else I know of. If you do replace it you can get a waterproof particle board. They just use a waterproof glue in it. I used it on my countertops when I redid our kitchen over ten years ago and it has not had any moisture damage at all.


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## mzimmers (Sep 6, 2007)

OK…the implications here are a bit unsettling, as this is underneath cabinetry. Am I looking at a major kitchen renovation here?

Again, this part of the subfloor doesn't have to do anything…it just sits there, about 5" below the floor of the cabinet.


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## BillWhite (Jul 23, 2007)

Is it particle board or osb? Has it thoroughly dried? If it has dried, is osb, and is not a structural element, maybe a good coat of a latex primer will seal it.
Bill


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## Grandpa (Jan 28, 2011)

My experience with particle board in this situation has been that it will bow up and then dry but it will NEVER flatten again. It will remain bowed. It will still be hard and support the cleaner you on it or whatever you put down there. You are dealing with a cosmetic situation. You can over lay it with another piece of plywood….maybe thinner plywood or leave it. The concern I see that you have is how to seal it to prevent the soaking and swelling the next time. Prime and paint with good stuff is about all you can do. You might seal it with a clear product if you want. Shop around and get a good product. Taking this out and replacing it will be very difficult.


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## mzimmers (Sep 6, 2007)

Thanks for the input, guys. I got a space heater in there, and dried out the sub-floor. Since it was intact (though slightly bowed), I just installed a shelf about 3" above it with MDF, and will live with it.

Now, I have to figure out how to waterproof the MDF. I could paint it, or cover it with vinyl sheeting. Not sure which way to go here, but…the original issue is resolved.

Thanks again.


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## crank49 (Apr 7, 2010)

I have lined the bottom of under sink cabinets with vinyl flooring; the soft flexible type.

You have to cover every square inch and even turn it up about an inch around the walls.

Then Get some white silicon caulk and seal the flooring to the pipe penetrations, if there are any, and the seams in the corners.

Now you have a waterproof pan under the sink that will drain out the front where you can see it if you ever have another leak.

By the way, I would have painted that swollen partical board with primer treated with mildewcide to prevent mold growth before covering it up. But, if you got it really dry, you might be okay.


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## childress (Sep 14, 2008)

kilz2....

...and you're done. get a couple of good coats on it once it's completely dry and then put your cabinet back together.


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## childress (Sep 14, 2008)

Oh. didn't finish reading where you put it back together already…. 

not sure a space heater will completely dry it out though. I would have used a dehumidifier….


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## renners (Apr 9, 2010)

If you want to make your new shelf completely waterproof, apply a 'tanking' product and paint over it. Tanking is the stuff they use in wetrooms before tiling to create an impermeable barrier between tile and wall/floor. You'd get it in a good tile or bathroom store.


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## mzimmers (Sep 6, 2007)

The sub-floor looked OK after it was exposed to the air for a couple days. I've already built the shelf over it, though I could take it back up easily (I screwed it in).

Now, I just have to find a place that will sell me a small remnant of lino or vinyl to put on top…the smallest piece I've found so far is 6'x9' and they wanted like $24 for it…


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## Grandpa (Jan 28, 2011)

Just keep calling shops that install vinyl and tell them you need a remnant. I have gotten small pieces with perseverance.


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