Can I or Should I Sand Drywall?

Question

We're re-doing our kitchen that was built in 1980. The old countertops were cement & tile with the tile continuing into the backsplash on the wall.

We've removed the old counters, backsplash, and cabinets which has given us a better look at the current drywall situation:

As you can see there is still a significant amount of binding agent left over from where the tile backsplash was (it seems like cement but idk). Overall though, it seems like the drywall is in decent shape so I don't think we need all out replacement.

We are getting new cabinets and countertops and plan on doing another tile backsplash that has a similar (but probably not identical) footprint where the previous backsplash was.

Based on my research, we should be removing the old material in order to make sure the new tiles can be installed flush and bind successfully. My first instinct was to use our handheld orbital sander to try to remove it. Is there a better way?

Answer 1

Sanding is not a good idea as the material you are trying to sand off is known as thinset or mastic ; it is a mortar like cement by the time you sand it off you will most likely damage the dry wall.

The process is to first scrape it with a scraper and then use a razor scraper - very time consuming and it will not be perfect. You can then come back with high grain sand paper if need be. Patience is your friend here..

If a bit of the dry wall paper comes off :

• If the new backsplash will be covering it: Just use your thinset/mastic liek normal it will cover it and protect it.

• If it is in an area where the new back splash will not cover - apply a very thin layer of joint compound in multiple steps with a 6" - 8" wide putty knife.. allow to dry between steps. Lightly sand and you will be fine.

Because your back splash is about the location of the divide between upper and lower wall - replacing the entire dry wall would require both upper and lower drywall sections (for that kitchen about 10-12 boards $150.00) - not hard and not very expensive .. just depends on how your removal work turns out.

Again this will be dependent on you as to if you want or need to replace / repair a section.

Answer 2

Assuming you are doing a similar layout I would finish removing the cabinets. Then I would cut two inches beyond the existing tiled area and put in new drywall in the middle part of the wall. Most of your seams would be hidden by the cabinets or the tile so it wouldn't require a lot of finishing.

Answer 3

Drywall surface is paper. They can be peeled off.

Sanding is doable, but you risk going through the paper because the material is so much weaker than your sander.

Something like a scraper will work, but once you start peeling off the drywall outer paper, you want a sharp knife to control the peel so you don't rip off more than intended.

If things don't work out, you can just cut off the whole area and do a drywall repair.

Answer 4

Thank you for everyone's advice; I tackled the project over the weekend and thought I'd post my method as an answer as well.

Took about 6 hours but I was able to remove almost all of the thinset from the walls. Since a new tile backsplash will be installed where the old one was, I think it doesn't have to be perfect.

I first started manually using a 3" flat head chisel to try getting as much off the walls as possible. It was very labor intensive but actually quite effective. For the areas that I couldn't get all the thinset removed I used the handheld orbital sander to sand it down smooth.

About halfway in our flooring contractors showed up and offered me one of these:

Which worked like a charm. I was able to use this oscillating tool to get between the drywall and thinset and chip most of it off. Again, where I couldn't get all of the thinset removed, I went over it with the sander to smooth it out.