Subfloor layers.

Hi all-
I ripped up some pergo-like flooring to put in tile in the kitchen but I'm not sure what exactly I have underneath and am trying to figure out my best bet for what to pull up and what I need to put down.
The plywood is the exposed layer right now except in one corner where it came up and I can see a bit of a cross-section.

Here are the four layers I think are there from top to bottom:

1) ====PERGO LAMINATE (PULLED UP)=====CABINETS/APPLIANCES installed on this layer with shims ==

2) =====PLYWOOD, FLUSH WITH ORIGINAL PARQUET IN NEXT ROOM ====

3) ============POSSIBLE OLD TILING (seems to be in tile size pieces and doesn't readily scratch) =======================

4) ============CEMENT SLAB? (I know there is cement slab down there somewhere)==========================

Building was built in 1968 and renovated heavily in 1978.

Thanks for the advice.

You'll have to do better than "Cement Slab", question mark. How can there be any doubt?

If it is concrete down there someplace, the plywood was a bad idea. Remove everything until you find concrete, then let us know what the conditions are. If there is some kind of vinyl tile under the plywood, it may contain asbestos, so don't be sanding anything.

Jaz

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===================Agreed!=======
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Any advice on getting the plywood layer up? Its all glue. No screws or nails. Whatever adhesive is on there its very secure.

HOLD ON!

Are Schnitz411 and David the same person?

Yup they are both me. Sorry about that confusion. First time using this forum.

So you think plywood is glued directly to existing tile? Though not the easiest thing to do the plywood should be able to be pryed away from the tile. In the past we have used heavy iron bars to do this type of removal. These tools are available at home centers.

It may be necessary to use a circular saw to cut grooves in the plywood to reduce the size of the pieces being removed. Smaller pieces are of course much more manageable.

Ok some progress here.
Got a big prybar and have discovered that under hte plywood layers is about a 1/8" layer of dried up, gummy adhesive that is grey/green in color and goes all the way across in one big piece. It is somewhat brittle. Thats what I thought was tile before.
Under THAT is a black layer that seems like a dense sort of rubber, but it will take dome doing to get under that because of the angles.
Any ideas on what this stuff is?

Ok some progress here.
Got a big prybar and have discovered that under hte plywood layers is about a 1/8" layer of dried up, gummy adhesive that is grey/green in color and goes all the way across in one big piece. It is somewhat brittle.

It can't be "gummy" and "brittle" at the same time.

Thats what I thought was tile before.

So now there is no tile?

Under THAT is a black layer that seems like a dense sort of rubber, but it will take dome doing to get under that because of the angles.
Any ideas on what this stuff is?

Have no idea what you have gotten yourself into!

Doesn't matter, if your goal is to get back down to the concrete you say is down there somewhere.

Git-r-done!

OK it is harder then I expected.

I do know 100% that there is concrete slab down there. Its in the original construction docs for the building.

It sounds likely that this stuff is "cutback adhesive": do I have to worry about asbestos? Some suggest there is thinset that I can put on top of the cutback?

Scrape the cutback, keeping it wet, with a razor scraper and remove it to a staining and you can go over that with any thinset that says it's for going over cutback adhesive. There very well could be asbestos in it, but it's not friable unless you sand it or grind it. Wet scraping will be just fine.

Sounds like you have some height to build up to get the floor even with what's joining it or will you be fine with the level of the installed tile?

OK egg on my face again. As more of the plywood comes up its clear that the layer below the plywood and above the cutback, is some tiling. My condo documents say that in 1979 there was "installation of new vinyl-asbestos flooring" and it seems likely this is that stuff. Does the wetting approach work for this? Respirator needed?

In terms of height, the plywood was flush with the parquet in the next room so I may be a little low but close.

Condo? You didn't mention that before.

So, is this on the first floor or 2nd or higher floor? That concrete you've been looking for may be Gypcrete. That may cause you several new problems.

We're trying to help but we need better descriptions of what is what there.

Jaz

OK guys. Sorry for the poor info. As you can tell, I'm new at this.

Let me lay it all out in one place:
3rd floor condo (9 story building), built in about 1970 and converted to condos about a decade later. That conversion is when the VAT was likely installed in the kitchens, although I don't know what was there before that and if it was covered or torn up.

In the rest of the apartment I have original parquet (not sure if its from 1970 or 1979 -- I think '70 from others in the building) that had been covered by carpet and pergo but I just ripped up. I do not know what is immediately under the parquet as it was in good shape and didn't come up.

The kitchen had the same pergo. Under the pergo was the plywood which is now coming up in large pieces fairly easily. This is basically flush/level with the parquet.

Under the plywood is what I believe now is the VAT I know was installed around 1979. Its sort of a grayish/greenish, very thin, 9" inch square setup. It seems that it will readily snap off in chunks but isn't crumbling. The plywood is coming up (although glued) with basically no damage to the tile layer.
In the few places that the tile has pulled it up, it has the black tar-looking substance underneath that I'm assuming is cutback.
Given what I know of the history and where things line up with the other flooring and the apartment threshold and hall floors, I don't think there is another layer of actual flooring down there. I am assuming that it is the concrete slab under the cutback, but the building documentation I have is not specific.

The current plan is to finish prying off the plywood, then soak the tiling with a water/detergent mixture and pop it up in large pieces, then do similar to scrape back the adhesive under it. After that, hopefully will be at the "bottom" and use thinset and tile from there.

Hope that clears up any confusion and appreciate the ongoing help.

Update:
A few hours of prying and scraping and I've gotten down to the cutback on the whole floor.
The cutback came up with the old tile in some spots, but mostly looks like its gonna be slow going to try to scrape down.
Underneath is concrete (or Gypcrete possibly as you guys suggested?)
After I finish scraping as much as will come off, should I be looking at Plani-Patch to coat the residue and/or something to self-level?
Thanks!

Bumping back up and updating:

Have wetscraped down the cutback pretty well and have a stain only at this point. Concrete is definetly not totally level. Bumps and depressions but probably nothing over 1/4" inch at most.

Spoke with building engineer and he isn't sure about gypcrete vs "regular" concrete, but said he would guess concrete. Also, he said it has post-tension cables. I don't know if that is indicative one way or the other

Current plan is:
LevelQuik latex primer
Then LevlQuik for a self-levelled underlayment.

If this sounds right, two questions:
1) for a kitchen do I need to worry about a waterproof membrane? I assume not but double checking.
2) how thick should the levelquik be? I have almost exactly a 50sf area which is what the instructions say is good for 1/8".