My walls are the old plaster type and I have always hated them. Is it possible to put knotty pine over them, and how much prep would be involved? I really love the look of the old barn board. -Diane
You would be adding a lot of weight so should demolish the lathe and plaster. You are going to need to have structure to nail the barn board to anyhow. Your outlets and switch boxes are going to have to be moved forward or you can get extenders.
If the wall are flat, you might be able to get away with that thin "faux barn board" stuff. It will look awful and be a nightmare if your walls are not flat.
Best to loose the plaster and lath. Your going to have to put up horizontal strips of 1X's to have something to attach the boards to.
I hope your not planning to sell soon. your one of the few people that would want that type walls.
Notty pine went out of fashion many many years ago.