What type of roll-on sealant would you recommend to seal up a plywood subfloor?
Semco is one that I keep hearing about, but I can't find any at Home Depot or Lowe's near Covington/Maple Valley.

I'm building a large chicken brooder with a 4x8 floor. It'll hold up to 50 chicks for 4-6 weeks, depending on breed, with weekly cleanouts. Meat birds shit a LOT so I'm trying to find a sealant that I can put down on the floor and 3" up to help it stay dry.

Similarly, I'm building a large chicken coop over 4" compacted gravel. I'm laying a piece of heavy-duty plastic over the gravel, covering it with about 1" sand and then putting PT 2x6s suspended about 1-2" off of that sand. I don't expect a ton of moisture as I've been monitoring the gravel pad under the chicken run since early January and it hasn't been visibly wet. However, anything could happen if we got weeks of heavy rain.

Therefore I'm considering attempting to seal both the under and topside of the OSB tongue and groove subflooring.

What would you recommend?

Back in my day 30 years ago, we didn't do any of this waterproofing shit when we built Arby's restaurants. So I'm lacking in experience as to how to balance cost (the sealers are hugely expensive) with function (does the most expensive = the best?).

Go to Lowe’s or Home Depot and rummage through the vinyl flooring cutoff bin

FRP is another option but even the textured stuff is going to be slick. It’s really meant for walls and ceilings

I agree that sheet vinyl would be the easiest to maintain.

Behr makes a product called "deck over". You will want to prime the subfloor with Killz Primer, then apply the Deck Over. downside is chicken shit is acidic, so any type of paint product will be compromised, and scratch with the shovel cleanups. Back to sheet vinyl and easy....

What is FRP?
Yeah, the vinyl flooring is going to be the trick for the coop. The brooder is going to be a problem because if it is too slick the chicks can't get their footing and they will develop splayed legs.
But, it sounds as though either way there might be a problem with a painted surface or vinyl. Maybe the trick is just a super thick bedding of shavings.



Well, that Deck Over at 45 + Kilz at $24 is way cheaper than Semco Liquid Membrane at 109 on sale!

How smooth is that Deck Over when dried? We can certainly use plastic tools if necessary. But I hadn't considered the acidity ruining paint....

How worried should I be about coating the underside of the coop floor (OSB subfloor)? Sitting 7" off the ground layered over in plastic? Am I worried about nothing in this application?

last about a yr and half, crap if you ask me.



was going to say vinyl the way to go too, easy to hose out

Kilz is probably not going to seal osb well. Try minwax or masterline oil polyurethane finish. It’s relatively tough, goes on thick and seals very well. A gallon should be $22-$27 and will cover about 500 sq ft. I’d recommend 2-3 coats and sprinkle silica sand in each coat while wet to make non-slip.

There is a company called Tech Supply. They sell a product that would work well for your use. It is used for the walls in livestock barns so you can power wash the walls. It will come to you in a tube tolled up. I used a sheet of it for a travel trailer tub surround 30 years ago. Great stuff.

Flex Seal? I have no experience with it but I've seen the commercial.

There's also a product called Liquid Rubber which might work too.

I'm not seeing anything in a search. Are you easily able to find a link?

I've also seen the Flex Seal! they're well known for wet sealants for current leaks. Wasn't aware they had a paint-on product.
liquid rubber is interesting! looking at that further!


That's an interesting idea. Will explore that further.

Thanks for the suggestions, folks!

It sounds like something super cheap underneath and then vinyl is going to be the very best option.

Just buy treated plywood. OSB is garbage

No doubt. But have you seen the price of pressure treated plywood lately?
It is $70/sheet. I can spend $11/sheet + 50-70 on a treatment solution and still be way far ahead. Or so it appears.

I don't know shit, but I'm just guessing that it's this:
https://www.teksupply.com/cat/ts-polymax.html