I have several questions about laying plank porcelain tile on a concrete slab. First do I need to get 100% of the glue from the concrete floor, there are small spots and patches here and there that still have a very thin layer on it. I used glue remover to get as much as I could off.
Secondly there is paint spots on the floor from when the house was first built, do I have to remove 100% of this material, I scrapped and scrapped and I am getting tire of it. There are also spots left from when I sprayed texture, does this have to remove 100%.

My final question is should I should I use self leveling concrete on the slab, I notice when I poured water on the floor there where some low spots, what is acceptable and what isn't?

1 Answer 1


You should try to get things that have height off your floor. A little glue stained on your floor, paint, stuff like that - won't hurt anything. The thinset will bind to that just as good as the concrete. So you want to make sure anything sticking up is scraped and anything that is loose.

Leveling is not a must. Most basements slant towards the drain. Whether you level your basement is based on:

  1. How big the tiles are. The bigger the tiles the more level the basement needs to be. If you were doing mosaics you could handle any slant.

  2. Whether you care about drainage. You may want to keep the slant on a basement predisposed to have water issues.

  3. How good of a tiler you are. If you don't have experience tiling, a floor far from flat can be really challenging. You basically have to use different amounts of thinset to even out your tiles. I have seen this turn into a disaster for some. Definitely takes some planning.

  • Also considered putting down some ditra mat if your floor is at all green or has any cracks.
    – user23534
    Oct 24, 2014 at 23:35

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