Here is a simple method to patch textured drywall but will also work to patch smooth drywall.
In the photo below the plumbing for a sink was moved to be in the left corner from the center of the wall. I had cut the existing rock out so I could sweat the copper pipe in the new location. The rock was cut to the center of the studs on both sides. After setting the copper and drains I cut for the pipes and screwed the rock to the studs. I used paper tape and 90 minute mud to tape the joints. I taped all of the joints at once.
So how do you deal with the existing textured side of the joint?
After the mud begins to set up, maybe ten minutes, take the sponge and dab down the thick line created on the textured side. This flattens it and adds some texture. Sometimes one pass will be a finish, other times you will need to float it out further.
Always use the sponge to knock down that line a bit. After you can sand it a bit before priming. In both photos you can see the haze outside the mudded areas that is created when sponging. This gets painted over later.
This is a small area so I recommend buying spray texture. Follow the instructions and tape off anything you don’t want to clean later. Spray texture also stains wood so be careful. Note: I do all patching and painting before any floor s are finished that way you do not need to tape and cover finish flooring.
Unfortunately, I did not take a photo before finishing the sink install but here you can see that the hole where the sink was is patched as if there were never a remodel. Hope this post helps with your sheet rock repair.
For more tips on sheetrock repair see “How I repair sheetrock II”.