I just bought a cheap but habitable older house (built in 1920 according to the listing) in the Pittsburgh area. The interior walls on the ground floor and some of the second floor bedrooms appear to be something like painted over cardboard (at least, the lady I had over to give a quote to redo the bathroom said it looks like cardboard. I’m a first-time homeowner and my parents have only had houses built after 2000. I don’t know anything.). Inspection said that the walls were plaster. As you can see in the photos, it’s some brown sheet thing underneath the paint.
The previous homeowner was unable to afford proper repairs and was literally taping things together (see the second-to-last photo). It seems beyond repair, so I’d like to get rid of it and paint my walls some nice colours and make them look like not-crap.
I’ve already received advice to use caulk and mud to fill in cracks/holes respectively, but how do I remove the cardboard stuff (if it is cardboard)? And how do I tell if the underlying material is plaster or something I can paint directly on, or if I’ll need to put drywall over it?
There are also some areas that are painted without the cardboardy thing covering the walls and some wallpapered areas.