Uneven plywood subfloor

[seagull369]

My apologies in advance if this question hasn't been asked a bunch of times already I tried a search but didn't come up with much

I've got a plywood subfloor that's uneven and wasn't sure exactly how to go about tackling it. I eventually want to put tile on top, but obviously cant do with a base that's in that state,

The subfloor is uneven in part from gobs of Goop adhesive good old pop used to re-secure tiles that were on there originally The dog also, uhm, had some mishaps in sections that have caused the plywood to delaminate slightly in sections.

My first inclination is to just tear out the bad sections and lay new osb in its place, but there is sprayed foam insulation on the underside of the boards that I'm a little hesitant to disturb

Would I be wasting my time to try and level off what's there or should I just get the saw out and start cutting?

Happy holidays to everyone, btw!

 

[BigGarage]

should I just get the saw out and start cutting?

Happy holidays to everyone, btw!

Get out the saw.

Dennis

 

[acer66]

Pictures would help and also what is your definition of slightly delaminating?

Adhesive leftovers can be scraped or sanded down using a belt sander etc.

If you have the height you can also lay another layer of ply,
glued and screwed, on top after removing the worst
which also would help with the future tile floor
because the floor would be less bouncy.

Cutting out the ply would be my last resort because of the spray foam.

 

[DPG]

"The subfloor is uneven in part from gobs of Goop adhesive good old pop used to re-secure tiles that were on there originally The dog also, uhm, had some mishaps in sections that have caused the plywood to delaminate slightly in sections."


If the dog has peed there so often that the floor is delaminating, 1st off would be to train the dog to go elsewhere. Then as Dennis mentioned, get out the saw.

 

[acer66]

Somehow I missed the dog part so the circular saw treatment might be in order.

 

[GRivera]

How large of an area? If not too large and transition to another floor/doorway isn’t an issue you can install 1/4” cement backer board as a good foundation for your tile job.

 

[Tom Sestito]

If the dog pee is not too bad, use some bleach to clean and a power planer to flatten. Expect to hit metal fasteners.

 

[juddspaintballs]

Cut out and patch the delaminated sections. Then, leveling compound should fix the uneven portions and be the perfect starting point for laying tile.

 

[chemist_slime]

I would first try renting a drum sander from home depot and go over the uneven surfaces. It's pretty cheap at about 60 buck for 4 hours or 70 bucks for the day. For any area that's still uneven, then perhaps replace those areas.

 

[seagull369]

Sorry for the delay and thanks for all the replies thus far

The peed on section encompasses about a 15'x10' section. Not every spot in that area are affected, though. The tiles were small mosaic-style which were simply mortared directly to the plywood, so as you can imagine when the dog went a lot of it worked it's way around all the grout lines right down into the wood. The dog has since passed away, so training it would be a little late . I'm just here to clean up the aftermath.

There is a transition spot upon entering the room and I did plan on Durocking everything from there on in prior to laying down new tile. I'm not sure how low-spot friendly that kind of board is, though, and perhaps that's what prompted this post. A drum sander is certainly a good idea for (evenly) knocking down the high spots from the remaining glue and embedded tile pieces, but do you think I could get away using a regular belt sander? I know the results won't be as level, but if cement board is going to be on top of that anyway, perhaps it won't matter that much.

I can't really take pictures because I have a sheet vinyl flooring tacked down all over to give mom something to walk on while I get this situation figured out.

 

[Brianc500]

If you can repair the de-laminated areas, and removed as much of the mortar as possible it might be a good candidate for a floor leveling compound. There's a primer that would go down first that makes sure the floor leveling sticks, so it only needs to be broom swept level clean prior to pouring. The leveling compound will flow out and self level and create a new flat surface to lay any kind of flooring on top. Depending on the floor joist situation even replacing the sub floor may not fix your level issue, so i would recommend the floor leveling compound to get a really true flat surface to work with.

Leveling compound

Primer

 

[PugetDude]

Here you go... rent from HD or any full-service rental yard.

I've used these before, they're easier to control than a drum sander and do a great job. Get a couple of sheets of sandpaper and a backing pad- you can return the unused sheets.
Fast and easy, and it won't dig furrows in your floor like a drum sander.
It takes some experience to run a drum sander, especially on softwoods....

Bleach will neutralize the pet odors- do it after you've sanded, wait a few days for it to dry and then hit it with a couple of coats of KILZ.

 

[seagull369]

Depending on the floor joist situation even replacing the sub floor may not fix your level issue

The joists are fine. It's just the plywood that's at issue.

Thanks for all the helpful info, everyone.

 

[MoonRise]

Adhesive blobs on top of the plywood?

Just remove them via 'appropriate' means.

Delaminating plywood, caused by 'liquid'?

Remove and replace the plywood subfloor where there is subfloor damage (and delamination IS damage).