How do I smooth a hump in wall?

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.

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.

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.

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

https://www.hometalk.com/diy/repair/drywall/why-i-learned-how-to-patch-drywall-and-you-should-too-2371202

https://www.hometalk.com/diy/repair/drywall/how-to-patch-large-drywall-holes-30536051

https://www.hometalk.com/diy/repair/drywall/the-easiest-drywall-patch-43612958

https://www.hometalk.com/diy/repair/drywall/learn-how-to-patch-a-hole-in-drywall-22555804

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.

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.

Hello,

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

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

Here's a post that might help https://www.askthebuilder.com/how-to-disguise-a-hump-in-a-wall-or-ceiling/

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

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!!!