How do i level a cork subfloor?

[evercl92]

Background: i had previously glued down 1/2" cork to concrete basement floor. We had put some rugs down but never did anything with it otherwise.

Fast forward several years, we are now inclined to put down flooring, ideally LVP. I thought we had a pretty flat resulting floor, until we went to install. The flooring won't snap together since it has some bowing in it.

What are my options for leveling this out? Does a cork- appropriate self leveler exist?

[PoorUB]

I would be inclined to rip out the cork, (yeah, I know, huge job!) and use for leveler over the concrete.

[duneslider]

I am not aware of any self leveler that would work over the top of cork flooring. Have you checked the floor for flatness with a long straight edge? Most flooring calls for no deviation greater than 1/4" in 10'.

If you can mark the high spots you could used a belt sander, or some other sander to knock down all the high spots to get it flat. You are going for FLAT, not LEVEL. LEVEL floors can be really difficult to achieve and cost lots of money typically. Pretty flat is achievable.

[evercl92]

I like your thoughts on flat vs level. I guess that's a possible option. I'm at about 3/8" over 4ft - just in the center of the room

[bluedog225]

2x4x8 dead flat board with 80 grit on the narrow edge (in this application). Maybe larger. They use something like that on wood boat hulls to fare large areas. I think they are called torture boards.

[evercl92]

2x4x8 dead flat board with 80 grit on the narrow edge (in this application). Maybe larger. They use something like that on wood boat hulls to fare large areas. I think they are called torture boards.

If i'm picturing this correctly, I would be "hand-sanding" with the board ?

[bluedog225]

Yes. This is the only pic I could find. Hope you get the idea. With an 8 or 10 foot board, you could wear down the “hump” given you have 1/2 inch to work with. And cork is the easiest thing I can imagine to work with on an issue like this.

[duneslider]

所以,当我想要安装的屋顶平面l I go around with my 10' straight edge and find my highs and lows. Generally this is over concrete so I just use a pencil to mark the high areas and low areas. Then I figure out how to address the issue.

3/8" is a LOT, is this a ridge or just a hump in the floor? I am guessing your cork flooring is only 3/8-1/2" thick right? IF the area isn't too large you could just sand down the cork in the bad areas. If you mark it out you can just hit the high areas with a belt sander and take it down pretty quick. If the area is large that is high then you could remove the cork in the high areas and fill back in with self leveler.

I would want to try sanding first as that would be an easier route. Again, you are looking for a level of flatness and not LEVEL. We level rooms for MRI machines, everything else we are just shooting for some level of flat... Most flooring is looking for at least 1/4" in ten feet. That isn't always a great standard for LVP and other floating floors. For thinset tile, 1/4 in 10 is fine and not generally worth spending money to flatten.

[evercl92]

The fun part is that its a dip in the center of the room rather than a hump. In my mind, thats sanding down 4ft x 15ft area, on both sides of the dip. Then similar area down the center of the adjacent room.
The cork is 1/2" sheets that are firmly glued down. It would be a tremendous amount of work to get them up. So much so i dont see it as an option.

[Michigan Mike]

If its a dip is it possible to fill that with another layer of cork and then sand that down. Just trying to think outside the box.

[duneslider]

I keep trying to rack my brain on how to make this work without tearing things out but I am struggling to come up with good ideas. How big is the area that is "low"?

What about just tearing out the low area and using self leveler in the low area?

I know there are cork products that are designed to be sound isolation underlayments for tile and you can tile over them. I would be hesitant to try and put self leveler over cork, I am sure it would stick fine, I just don't know what the long term reliability of the leveler would be. I see the edges breaking up over time and turning to powder.

If it were my house I would sand the low area to give it a good surface and paint on the self leveler primer, pour the self leveler. Once dry give it a coat of hydroban membrane running at least 3 inches past the edge of SLC then run my LVP pad and LVP over it. I suspect it will last longer than I would like the LVP and then when I want a different flooring I can see how my science experiment worked out.

For a paying customer that I had to warranty the work, I would be tearing out all the cork.

I do questionable things in my own house and generally they work out but for paying customers I have to consider my warranty and reputation, so I limit my exposure.

[evercl92]

I just measured one of the dips - this is from edge to edge - 34" wide, 60" long and 1/4" depth at worst.

Just so we're clear, this is in my own house, not a customer. I'm with you, I will do some goofy things in my house that I'm willing to risk having to correct later.

[evercl92]

How about this - short of trying to fix the cork, what options do I have for flooring?
We've already caved and are going to do carpet in one of the rooms, but looking for a "flat" option for the the other area.

[PoorUB]

I still recommend ripping out the cork.

You can rent motorized machines for stripping floor tile, I would assume it will peel up cork just as well.

https://www.homedepot.com/p/Tomahaw...nyl-Carpet-Wood-Floor-Remover-TSCP8/313305958

[evercl92]

That looks like a fun weapon. Can't be any worse than the concrete grinder I rented over summer.

[duneslider]

Those floor strippers work really good, especially over concrete. I have found that stuff glued down over concrete in basements tends to come up fairly easy. Basements tend to be just damp enough to degrade the glue.

LVP is pretty forgiving since it is soft enough to roll with the floor. If you can get it to click together it should be fine on the floor you have but you will see some waves in the floor.

理想情况下,去除软木和获得floor flat will provide the best results.