Particle Board Subfloor + Animal Pee = Trouble
December 5, 2021 8:27 PM   Subscribe

My mom bought a house. I was not present when she viewed the house; it is 3 hours from me. I have been there now that she owns it, and it smells strongly of urine - especially the master bedroom. The carpet has been removed and her plan is to install the very thin pergo-type flooring left behind by the sellers. It's about 1/8" thick. Unfortunately the subfloor is made of particle board, which of course, is stained with cat or dog pee (or both).

My mom is 78 and poor (as poor as you can be and still finance a house) and I don't have the funds to help her remove the subfloor and replace it with plywood or other material prior to installing the 1/8" flooring material and occupying the house. Is there anything that can be done to neutralize the odor before trapping it under the 1/8" floor?

Where the house is in central Oregon there is summer heat (>100F) and winter cold (occasionally around 0F) as well as some humidity year-round. She has electric baseboard heaters and a relatively unexplored crawlspace. She's going to smell the urine all winter while the heat is on and the windows closed.

She is considering painting the particle board with Kilz before installing the 1/8" flooring, but the 1/8" flooring requires glue and we are concerned that the glue will not adhere to the Kilz.

Any idea? Is removal of the pee-stained particle board the only reliable solution?

Thanks in advance.
posted by happy_cat to Home & Garden (17 answers total) 2 users marked this as a favorite
Best answer: This is a guess not experience, but I would try spraying the subfloor with enzymatic pet-urine-destinkers. Maybe regularly for months. Before putting anything on it, Kilz or not.
posted by clew at 8:34 PM on December 5, 2021 [3 favorites]

Enzymatic cleaner followed by Kilz Original (I've used it to cover the smell from a house fire, and it was dang near miraculous. Kilz Original, not the newer stuff [they sell both in some markets]). Glue should adhere just fine unless it's an unusually weird glue -- carpet glue, for example, attached well.
posted by aramaic at 8:45 PM on December 5, 2021 [6 favorites]

I've never heard of particle board subflooring! In my opinion, this is going to be a problem long-term because particle board absorbs moisture - which I learned to my chagrin after some carpet steamers got moisture near my particle board + veneer book cases (the couldn't slip plastic under them because my bookcases are full )
posted by TimHare at 9:10 PM on December 5, 2021 [2 favorites]

In my experience, Kilz works well to trap and seal odors in particle board. It doesn't feel any different from regular paint once it's dry. I don't know why the glue wouldn't stick to it. Maybe try a small section and see if the gluing is a problem before painting the rest of the floor?
posted by dorey_oh at 12:01 AM on December 6, 2021

Best answer: I've never heard of particle board subflooring! In my opinion, this is going to be a problem long-term because particle board absorbs moisture

Particle board designed for flooring is much more water resistant than the kind used to make cheap furniture, which really does like to absorb water and swell into wet weetbix. Flooring board has much more binder in it than furniture board and should be about as resistant to water swelling as plywood. It's pretty common to see particleboard flooring get thoroughly soaked by rain during house construction as it's often laid before the walls or roof are complete, and it copes just fine with that. It's not designed for outdoor use and won't stand up to months of repeated rains - it would be no good on a deck, for example - but occasional floods don't really fuss it. We have had it in our bathroom (under masonite and vinyl) since a remodel 20 years ago and it's holding up well.

If the urine stains are visible, give each one a good wetting with an enzyme based pet odour remover. The way to use this stuff is to pour enough of it onto each stain that it spreads out in a puddle a little wider than the stain, then let it sit and dry by itself. The idea is to use about as much of the enzyme solution as the original volume of urine, giving the enzyme stuff the same opportunity to find wicking and soaking paths that the urine had, so it can follow the old dried urine all the way into its deepest hidey holes.

You'll probably also want to squirt a fair bit of the enzyme stuff around the edges of the floor. It's quite common for a cat or dog to add little Pet Facebook postings on the skirting board, especially in a room that already smells of urine, so you get non-obvious puddles that wick along the crack between the skirting board and the floor.

Air out the room while the enyzme solution soaks in and dries. Then close it up again for a couple of days and check how much de-stinkification you've achieved. You'll probably find it's quite a lot, and Kilz should easily lock in the rest. And once the Kilz has cured it should make a completely sound base for glues.
posted by flabdablet at 4:14 AM on December 6, 2021 [5 favorites]

Is it really particle board or the more common OSB (oriented strand board)? The particle board used in furniture (usually called MDF) is really too expensive, heavy, and prone to moisture damage. OSB is designed as a lightweight subflooring system and has much more water resistance.
posted by JoeZydeco at 5:09 AM on December 6, 2021 [1 favorite]

Response by poster: Hi all, thank you for the responses so far. I hadn't thought of an enzymatic cleaner and appreciate that suggestion.

I don't know for sure whether it is particle board or OSB. Unfortunately I'm back home now and can't recheck it. I did observe that in other parts of the house the floor is uneven, so I suspect additional subfloor swelling.
posted by happy_cat at 5:27 AM on December 6, 2021

I don't know for sure whether it is particle board or OSB.

In either case, if it's actually been designed as flooring board, and isn't simply any old crap pressed into service by some code-ignoring cowboy, a bit of cat and dog wee is very unlikely to have swelled it even slightly visibly.

in other parts of the house the floor is uneven, so I suspect additional subfloor swelling

If it's an older house, a more likely cause for an uneven floor is a bit of ground movement. Or if it's built on stumps, those might be deteriorating. Our place is on stumps, built in the 1950s, and some of our floors are actually visibly domed.
posted by flabdablet at 5:46 AM on December 6, 2021 [2 favorites]

The particle board used in furniture (usually called MDF) is really too expensive...

MDF and particleboard are not the same thing. Particleboard is made from much bigger pieces than MDF (though not as big as the pieces in OSB). MDF is made from wood that's been shredded apart into individual fibres, halfway to paper pulp but with the lignin left in. Both are used in cheap furniture, MDF more commonly in quite thin sheets for stuff like the bottoms of drawers or the backs of bookcases. IKEA's Billy bookcase, for example, is made from veneered particleboard with an MDF back sheet.
posted by flabdablet at 5:59 AM on December 6, 2021

Best answer: I recently tore out particle board subfloor in my bathrooms and replaced with OSB. Is the subfloor flat? If it’s not level to the tolerance for the new flooring, you’re not going to get a good result. Wood prices are down significantly from peak, strongly recommend tearing out the old subfloor and replacing with OSB if needed, getting in touch with social service agencies (Habitat for Humanity might have leads) to see if you can get assistance. If you do have particleboard, there should be another layer of subfloor underneath that you might be able to lay the flooring on directly. I would expect any liquid applied to particleboard would cause it to warp more, including cleaners. Kilz is not cheap, either, but you could apply that to try to get the smell down to a tolerable level while you work on a longer term solution. It should be durable enough once cured to walk on over the winter, at least. I’m concerned that if you can’t afford to do it correctly once, you really can’t afford to fix a bad job later + time pressure causes bad decisions. Ask me how I know.
posted by momus_window at 7:29 AM on December 6, 2021 [1 favorite]


Some - many - people are sensitive to it, and it's probably not healthy for the remainder.

Kilz contains fungicide, and fungicides are notoriously toxic to humans even when taken in medications.

We did this. I couldn't stay in my house for more than a day without getting the most incredible headaches and vomiting. I ended up having to move out.

There are other odor-sealing products that are designed to be non-toxic to humans.

We used AFM Safecoat from Green Building Supply to seal _on top of_ the Kilz, and I think it's designed to seal against odors generally. There are a lot of similar products offered by this company, though, and if you call them, they are extremely helpful. I was so messed up by the Kilz -- and when I called the manufacturer, they weren't surprised by this -- that I will give you the phone number for Green Building Supply right here: 888-941-0226.

I think it might be fairly expensive, but waaaay less than moving out of your house. Also, look for a local (or more local) distributor to save on shipping; you might even be able to get a local paint store to special order for you --> $0 shipping.
posted by amtho at 7:51 AM on December 6, 2021 [1 favorite]

Best answer: I waited for months for the Kilz off-gassing to "wear off". It didn't. Researching this after the fact revealed that lots of people have problems with this kind of thing.

As you know, once you put something on the subfloor, it's there forever -- please proceed with caution.
posted by amtho at 8:07 AM on December 6, 2021 [1 favorite]

Consider picking up a UV flashlight to help identify the less obvious pee stains. They’re less than $20, and make it much easier to find the less obvious sources of odor while you’re using the enzymatic cleaner.
posted by whisk(e)y neat at 2:02 PM on December 6, 2021 [3 favorites]

I meant to suggest: something like AFM Safecoat would probably work well to seal the current odor, and would be a lot less toxic.
posted by amtho at 4:46 PM on December 6, 2021 [1 favorite]

Response by poster: Thanks so much everyone.
posted by happy_cat at 4:55 PM on December 6, 2021

My understanding is that you need a shellac-based primer to seal it in. Kilz is one option, and shellac-based BIN is another.
posted by mortaddams at 7:27 PM on December 6, 2021

"Is removal of the pee-stained particle board the only reliable solution?"

Yes. You may even find that the pee has gone down into the joists below the particle board, through the seams, and into the first foot or two of baseboard/drywall/baseboard heaters. You may have to remove the particle board and treat the top and sides of the joists. You would have to let the joists dry before replacing the subfloor.

As amtho says above, Kilz can make you sick. It is a great product when no other product will do, but it offgasses for a long time. I could still smell it a year later, and yes it did give me headaches, even a year later, and even though it was encapsulated under another material like yours would be. It would be very risky to use Kilz on a bedroom subfloor. Watch out--you may also find that the glue used to put the Pergo down causes a negative reaction for your mom.

I suggest you contact your county agency on aging and see if they have a program for remediating housing issues like this. Often, they do, and they have someone come in to assess the situation. There are also companies that remediate this type of animal pee situation. You might call some of them for ideas or an estimate.
posted by KayQuestions at 9:03 PM on December 6, 2021 [1 favorite]

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