I’m a newbie who always called the “guy” for any and all lawn, interior/exterior home repairs. I recently bought a 1929 home and many of the walls are plaster. They are blatantly uneven with lots of holes. How do I fix them? Can I hang thin drywall over it, sand it down, or do I need to knock the walls down and then hang drywall?

plasterers in the day were pretty particular about laying even walls. so those crummy spots are there because somebody more recent has been chopping open walls to do something.

since they can't refinish walls, I postulate they did something that was not a positive. whatever workmanship is behind those rotten sections is probably subpar.

what I would do is take a fiber inspection camera, poke a couple half inch holes here and there, and see what they did. my hunch is that they were replacing knob and tube wiring, but considering the crummy patch work, they may have been replacing SOME of that stuff and doing creepy splices to the rest. in other words, window dressing. that kind of slop can actually increase the hazards.

Got some pictures?
Has the wiring ever been upgraded?
Any idea if there's even insulation in the walls?
Has a new elecrical panel been installed?
Reason I'm asking is if the walls are that bad that's a great time to get rid of the old plaster and lath, install new wiring, add fire blocking and insulate.