Doing some modifications to my house I've never drywalled before short of some spackling but I'm good with my hands
I forgot to take pics today but figured the knowledeable here would give me some ideas, so I'll try to describe in words.
The house has wall board, layered with mortar ontop and then skimcoated with plaster, so it's pretty thick, just over 3/4" on some walls, and closer to 1/2" and 5/8" on others which brings me to my problem.
I tore down some partition walls in my house so now have to patch where was torn down. At one of these patch areas the walls to be joined one is slightly thicker than the other. The difference is approx 3/8" in thickness. I don't care if it's perfect but it should look half way decent so I'm wondering what's the best way to go about doing this. I'm using 5/8" sheetrock to fill in the space- and the space is 40" wide because I cut down so I could make an in the wall shelf. I plan on trimming out the wall shelf with trim that was used from a door frame a wall that was taken down.
There are some challengers- I have a 4 gang electrical box for switches there right at where the uneven walls meet, so any kind of taper would likely be seen against the relatively wide wall plate cover.
Option 1: I would shim out the "patch" drywall sheet 3/8". I made some shims last night and did some test fitting- it looked good BUT I am worried this will affect the wall shelf trim (with one side being flush and the other having a slight gap) unless the sheetrock flexes enough to conform. And 5/8" doesn't seem to flex too much and even then it may crack later.
Option 2: Put in the sheetrock flat without the shims, sand down as much as I can on the "higher" wall and fill it in and taper the seam as best as possible with tape and setting type compound. The shelf trim will then be flat. BUT- sanding will only get me a little bit of skimcoat off the wall as the mortar is basically sand and stones and will not sand down, and the 4 gang light switch will show any kind of taper pretty easily.