tile over plywood over asbestos over concrete??
 

I have a concrete floor (above grade over garage) with some type of sheet flooring glued to it. It was put down in the late 1940's.

Can I screw down plywood or cement board to seal in the old floor and give me a new substrate for tile?

Thanks DIYérs

Bad plan---Ply over a concrete floor--even above grade---often puckers and swells,causing tile failure--

If the old sheet goods can not be removed easily--you could encapsulate it under a layer of self leveling compound-----then set the tile on top of that----

what about attaching cement board instead of plywood?
The sheet flooring is thick and spongy. I'm worried that it would not
be structurally sound enough for thinset and tile.
Thanks

You are going to have to remove that old floor covering----you can not attach cement backer over the concrete---

Sorry---is there a reason you don't want to remove it?

The next person that wants to install plywood (or a concrete backer) over concrete is gonna make me scream!! :huh:

Jaz

The old flooring is asbestos.
I install into concrete all the time. I could easily screw down cement board onto the concrete. Several concrete companies have told us encapsulation is not an option. They believe the bed and tiles will crack because of the spongy flooring. Asbestos removal here will cost far more than we have in our budget. Will screwing cement board down not work either?
We are running out of options here.