We have a small piece of wall under a window that had condensation/mould problems from a previous tenant. We took the wallpaper off and the wall looks like in the photo attachments. There is still some backing paper to come off, it’s a little uneven and rough, and a bit discoloured, but is dry (pretty sure the problem was condensation in the room, rather than dampness in the wall).
What do you suggest doing to the wall? We don’t have any wallpaper left that matches the rest of the room, but could put some thick plain paper over the top – as it’s under the window and surrounded by wood it wouldn’t be too noticeable that it wasn’t the same wallpaper. Or could plaster it and paint it; or plaster it, line it and paint it.
Also, underneath some of the plaster seems to be a slightly squishy yellow rubbery layer – never seen that before in a wall, any ideas what it is? Please don’t say it’s damp proofing.