We're living in a 200+ years old house, slowly renovating, and we're starting the second floor which is basically wood plank walls. Some of them have wallpaper on it, but most of them are painted.
Now Googling here and there, the only source I've found that mentioned plank wall there where already painted said to "sand the wall to remove old paint" before painting over.
Now my walls already have at least two layer of old paint and I feel link sanding it will take us forever... Would sanding it really be needed? Can't I just paint over the old paint?