I plan on removing the tub and change the window in in my bathroom.

The tiles started falling off this 23 year old house, so I removed the remaining ones. I tried to remove the mortar, but it is on stronger on the concrete wall than it was on the tiles.

On the top corners of the window I tried sanding down the mortar with a diamond wheel and a grinder, but it just created way to much dust and really didn't do much after about an hour.

Not really sure how to proceed.

Bathroom shot wide

bathroom shot close up 1 enter image description here enter image description here enter image description here enter image description here enter image description here

Any suggestions aside from hiring someone?

  • 1
    Are you sure it's concrete? Is the wall that the piping is in hollow? Could be mud bed walls or even plaster. You can get a shroud for the angle grinder that lets a shop vac hook up to control the dust. if it's mud bed over studs, you tear it out and put in a new surface. Also check out the John Bridge Forums. Commented Feb 15 at 17:41
  • A pulverizing bit for a rotary hammer (operating in hammer mode) can do it. In my experience the dust drops to the floor with air from the tool's exhaust port stirring things up a bit. See amazon.com/Bosch-HS1909-SDS-Max-Concrete-Bushing/dp/B0009H5P2M for an example, but I think you could get one for 20 USD if you shop around.
    – popham
    Commented Feb 15 at 18:59
  • 1
    Did you try wetting the wall first? I imagine that the thinset will suck the water right in. That might substitute a gray slurry problem for your dust problem.
    – popham
    Commented Feb 15 at 19:02
  • @aquaticapetheory The house is made of cinder blocks and concrete. The area around the valve has a big gaping home because I had it replaced.
    – Rick
    Commented Feb 16 at 0:28
  • 1
    @AloysiusDefenestrate a cup disc.
    – Rick
    Commented Feb 17 at 8:39

1 Answer 1


In cases like this you can go up or you can go down. You can level the surface to the high points, or you can reduce the surface to the low points. I'd argue that the former is much easier here.

Assuming that the remaining mortar or mastic is solid and secure, I'd first scrape or sand off any bumps to make the overall surface flat to the level of the trowel ridges. Then skim with new mortar, mastic, or setting-type joint compound to achieve a filled, flat, smooth surface.

Now tile as normal.

  • So can put thin set over the the existing mortar? Seems pretty hard as it is right now.
    – Rick
    Commented Feb 17 at 10:04
  • You usually can, but read the instructions.
    – isherwood
    Commented Feb 18 at 19:58

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