ITAW for only painting/wallpapering one wall?

We have a word for it in my langugage wich essentially means "foundation wall" and where you only wallpaper or paint one wall. but I really need to find what it might be called in English.

Google translate gave me "backscene" but it doesn't seem right as a search for it only brought me to photo backdrops, when I want it themed more towards interior decorating.