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I want to put some tiles on the wall behind the stove. The wall has plaster and is currently painted with a water-repelling paint. My idea is to sand off the paint and tile onto the plaster.

Now, I was checking the wall in preparation, and when I knock on the area that will hold the tiles, it sounds hollow in the top 15-20 cm or so, see here:

https://imgur.com/a/hbqmZNH

Pressing the wall I cannot notice any "give".

  1. Is this a problem that needs to be fixed first, or can I tile on top of this?

  2. Regardless, is it possible to fix it without redoing the plaster? I'm thinking, drill a few small holes and inject a low-viscous glue of sorts.

Any tips are appreciated.

PS: this is not a drywall. It is a brick wall covered with 2 layers of plaster. The house is old (110 years) but the top layer was done about 6 years ago.

2 Answers 2

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If there is no "give" and the wall is brick with plaster overlayed, I would be confident to tile right over it.
I would not sand the surface. I always tile right over waterproofed walls in showers and tub surrounds. Never a problem. Kitchen walls that are flat and firm the same.

The trick is to get the proper thin set or mastic for the tile you are setting. For a backsplash in a kitchen an acrylic mastic will work well. I use AcrylPro In wet areas you will need the thinset specified for the tile.

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  • Thank you for your answer @RMDman. To clarify, the coating is really quite slippery and I feel like there might be a problem with bonding anything for it. Buy you recon applying thinset directly will still work, correct?
    – ElRudi
    Commented May 19, 2023 at 10:20
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    I don't know your exact surface. An adhesive may be better than a thinset. There may be a light scuff of the surface needed. Not a complete sanding. Consult the professionals where you purchase your tile.
    – RMDman
    Commented May 19, 2023 at 11:03
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    I would do a light scuff, or take a wire hand brush to the painted wall.
    – Huesmann
    Commented May 19, 2023 at 13:19
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I had a house with a similar issue with plaster:

We had removed about 6 layers of wall paper and an area of plaster (old plaster with horsehair) was coming off the wall - about 4 square feet.

So I made a few holes at the top and squirted glue generously behind the plaster then compressed the plaster against the wall using some wood beams wedged on the floor. Never moved after that - sold the house 25 years ago so don't know what happened after...

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