Priming Cat Urine Stained Plywood Subfloors

[Another Reader]

I'm helping a friend that had way too many cats and now needs to sell her house.  After pulling out the urine soaked carpets and letting the plywood subfloors air out for a couple of weeks, it looks like we are going to have to seal the subfloors and replace the baseboards.  It's that or replace the plywood subfloor, which is not an option because of the cost.  Most oil-based primers cannot be purchased in California for environmental reasons, so I am looking for an alternative.  The shellac based Zinsser B-I-N primer has gotten good reviews for odor blocking on-line.  Has anyone successfully used this product to block animal urine odors?  Any other suggestions from folks that have had to deal with this?

[Spork]

Have you tried any of the enzymatic cleaners sold at pet stores?

I haven't done this with plywood (and I am unsure of how wet you'd have to get it or if that would damage things) but I have had luck with carpet with this method:
1) LIBERALLY douse with enzymatic cleaner once a day for 2 weeks
2) do not clean with anything else during that time or you'll make it angry.  You wouldn't like it when it is angry.

[GuitarStv]

I've used some Kilz primer to cover mouse urine on plywood in one old part of a wall that I tore apart.  It worked very well, but I think it was oil based.  The enzymatic cleaners that we tried first didn't do much of anything for our problem.  (Neither did vinegar, bleach, soap and water, lots of scrubbing, etc.)   Kilz does seem to offer water based primers too, they might be worth checking out.

[JohnGalt]

Kilz primer worked great to get rid of dog urine that soaked through carpet into the subfloor.

[Another Reader]

The enzymatic cleaners such as Nature's Miracle do not work in this situation.  Water-based latex primers are ineffective as well.  The labels do not mention odor blocking, and that is supported by on-line reviews of those products. 

I have successfully used the oil-based Kilz on concrete slabs with dog urine odors.  The product is not sold in California.  Supposedly Lowes carries the Zinsser B-I-N in store.  Home Depot carries it on-line but it cannot be shipped to California, so I will have to go to Lowes to determine if it is really available here.

[Jamesqf]

What really works for cat urine is Clorox (or generic bleach equivalents).  Sponge it on badly urine-stained places, and you will see it actually bubble as the active ingredient in the bleach (sodium hypochlorite, IIRC) decomposes the urine.  Air the rooms well (you really don't want to be inside breathing it for long), and repeat until the bubbles stop.

Went through this process about a decade ago, with my current house.  I'm still living here, so it worked!

[jesse.anne.o]

I had to do this once and hydrogen peroxide was the onlyl thing that worked for me - multiple treatments (although I didn't try bleach).  I found the recommendation on a home renovation site.

[gecko10x]

I've successfully used and enzymatic cleaner (Bac-out) on wood (and we use it all the time on our carpets), though I've never used it on plywood. We swear by that stuff.

[Rural]

I've had luck with agricultural vinegar (a much stronger acid than the stuff sold for home use, so use caution, read directions, etc.)

[Emg03063]

Metallic silver spray paint should seal the odor into the plywood, and create an effective odor barrier.  I've never tried it, but I have a friend who uses this technique on his flips, and says it works great.

[Hamster]

We had the same problem in our rental. Pulled out carpet, left a fan blowing on the plywood for a few days, sealed with killz x 3 coats but there was still some color bleeding through. We put down a plastic barrier (for laminate e.g. generic Pergo flooring), then covered it with the laminate flooring and never noticed the odor again. It's been over 5 years. I don't have any evidence to base this concern on, but I personally wouldn't trust carpet over the piss-soaked area as I'd be afraid it would slowly seep back through. YMMV.

You may want to replace or seal the bottom few feet of sheetrock as well if the soaked area is near a wall. I'm not sure how the cat piss climbs walls, but it apparently does, based on the same personal experience...

[AlexK]

The water based Kilz does not seal odors and the oil based Kilz does, I know from experience. The house I'm living in had pee smell and I sealed the subfloor with oil based Kilz. I don't know what part of CA you are in but in NV they have it at Home Depot and Lowes.

[Another Reader]

You can buy the shellac based Zinsser B-I-N here.  A painter I know said that works.  We are going to try that on one room and see how it goes.  Otherwise, a trip to Reno may be in order!

[jnik]

What really works for cat urine is Clorox (or generic bleach equivalents).  Sponge it on badly urine-stained places, and you will see it actually bubble as the active ingredient in the bleach (sodium hypochlorite, IIRC) decomposes the urine.  Air the rooms well (you really don't want to be inside breathing it for long), and repeat until the bubbles stop.

FWIW, what you're smelling in cat urine is ammonia. Ammonia + bleach == really really bad. Make your own decision given the quantities involved and go in with your eyes open...behind safety glasses.

[Forcus]

I used Dutch Boy with Arm & Hammer baking soda in it. Seemed to work well.

[ChristopherPhilip]

Zinzer here!  The smell might return, but well after the house is sold ;)  My brother had that problem.  I don't smell it, so perhaps he has the stigma.  Do a few coats if you want to be sure.

[c]

I know cat urine is different, but I follow this blog http://www.littlehouseonthecorner.com/cheap-bathroom-makeover/ where they had issues with dog urine soaked floors and a disgusting bathroom. They have a few tips on cleaning wood floors that might be helpful.