How do I smooth a hump in wall?


My home is over 60 years old but I wanted to put up a backsplash under my cabinets and above my sink. The wall is pretty smooth until you get up over the sink. There is a hump in wall about the size of an average hand. If you slide a leveler up the wall you would notice a point where the dryway starts to bulge. The hump is in-between the two studs behind the wall. Do I just need to do some serious sanding? Also almost all of the pipes in the house are behind this wall. I think its condensation causing the bulge. Any thoughts?

  13 answers
  • GrandmasHouseDIY GrandmasHouseDIY on Apr 07, 2021

    Hi Joslyn, I would definitely start with serious sanding - it could be from an old repair where they got a little too generous with the drywall mud. You could always cut it out and do a full patch. Because you're going to be covering it with a backsplash it would not need to be at all pretty - just flat lol.

  • Seth Seth on Apr 07, 2021

    Does it feel wet? If there is an issue with your pipes, you want to know for sure. Don't waste time sanding. I would cut out that area and see what is going on. It could just be the studs are not plumb or there might be blocking between the studs that is supporting the pipes. Since you are putting a backsplash over the area, you don't have to worry about doing a perfect repair. Once you know what is going on, you can decide how best to fix it or what type of backsplash material to use. Do you have a basement? Check below that area for evidence of leaking over time like stained or rotted wood.

  • I agree with Seth, I too would cut the area out (very very carefully since you don't know exactly what's going on or what's back there where) and patch it.

  • Kathy Gunter Law Kathy Gunter Law on Apr 07, 2021

    It has most likely gotten wet and bulged. I would cut out the small area and replace it. It's fairly easy to do. You can buy a 4x4 piece of drywall, then cut to size. Affix with screws, then finish with mud. I would use a barely damp sponge to smooth rather than sanding. Repeat finishing steps until smooth.

  • William William on Apr 07, 2021

    I agree with cutting the area out and patch it with drywall. Sanding will remove the surface paper and then into the chalky gypsum. You don't need to mud the patch since you will be covering it up. Just needs to be flat. here are a few ways to patch a hole in drywall

  • Redcatcec Redcatcec on Apr 07, 2021

    Yes, cut out the piece that is bulging and see what is going on behind the bump. If no evidence of a leak then replace the section with new drywall, drywall tape (either mesh or self stick) and mud it over. There is not reason to sand it if you are going to cover over where the bump was.

  • Em Em on Apr 07, 2021

    You need to KNOW what is behind the wall before you cut. Another option is to add bead board with Loctite construction glue. You can add a few spacers made from small pieces of shims to ease the transition to not show the bump as much. Put a few pieces on the wall to make a gradual transition from the bump to the rest of the wall. Add trim to the top and bottom and you won't notice the bump at all. Beadboard is easy to cut and under $20 for a 4' x 8' sheet at Home Depot.

  • Johnavallance82 Johnavallance82 on Apr 08, 2021


    Remove the plaster board and then Lag the pipes and then re-place the plaster board.

  • Betsy Betsy on Apr 08, 2021

    Hi Joslyn: Seems to be a problem behind that wall. I'd remove the drywall in that area and see what the issue is. You are going to be putting something over the area, so the patch doesn't have to be pretty :) But, I' certainly address the bulge as it will, eventually, bulge your backsplash too. And, you are facing an issue of mold and mildew which can become a larger and more urgent issue. Take a peek and see what's there, but be careful doing so. An easy to do a patch is to get a piece of drywall at least an inch larger than the hole, put it over the hole and make a mark on one side of the patch, going on to the wall. That way you will know which way the patch will be put in. Then, draw around the patch with a pencil and cut out along the line. Your patch will fit perfectly, if you match up the lines :) If you cut the patch out over some studs, you can screw the patch to the studs. Otherwise, get a couple of sticks that fit into the hole at least 2" on the top and sides, making a + out of them. Then, glue, or screw, them to the back of the drywall on the inside of the hole. If you screw them in, make holes in the sticks first. When they are dry and sturdy, put Spackle on the sticks and the edges of the opening and the patch and stick the patch into the hole. Let it dry and sand or use a moist cloth to get rid of any excess Spackle.

    Good luck

  • Bulge is probably caused by water damage. You might have to replace that section of drywall. Only way to know for sure is cut into the wall and see what is going on

  • Maura White Maura White on Apr 09, 2021

    Yes - sounds like water damage. You should cut it out and replace it with a piece of new drywall.

  • Annie Annie on Apr 12, 2021

    You might want to just open the wall up and take a look. Replacing a area with new dry wall is easy, especially if toy are going to tile over any way...Just Go For IT!!!