As I commented way-back, there's a garage-wall section which is partly an inside wall and partly outside, which makes things awkward for grouping/materials, One solution is a specific texture-map, but that makes it hard to redecorate. Better would be to make that wall from two magic-boxes. I think. A third trick is to use a single-sided square as a virtual wallpaper. In this realworld house, bookcases are the preferred option. They also improve acoustic and thermal insulation.