I switched to the interior for a bit and started working on the wallpaper, please ignore the rest as they're still placeholders!
Since I want to have parts of it peeled off, I thought the best option is to have the base wall (concrete or planks, concrete in my case) and the wallpaper as separate meshes layered on top of each other. In my case since I already had the mesh for the walls, I just duplicated it, deleted parts of it and offset the whole thing a tiny amount to use as a base for the wallpaper. Then I started adding divisions where necessary and detaching vertices to create the peeling and other random damage in Maya using non-linear deformations Bend and Wave.
Apart from that, I started building up a shader for the wallpaper. Right now I am able to vertex paint the opacity mask to erase parts of the wallpaper and also paint some worn off paper onto the albedo. I'm utilizing the 2-sided texturing node to have different textures on both sides of the wallpaper.I'll probably be using the remaining few vertex channels for dirt and moss, or I might use decals instead... will see!
The wallpaper maps were created procedurally (minus the pattern of course which was a black and white bitmap) in Substance Designer