Unable to answer "What material is this building's facade made of?" – Garages – https://osm.org/way/303073931 via StreetComplete_ee 63.0:

Dach für Fahrradständer + Mauer

Attached photo(s):
https://streetcomplete.app/p/337020.jpg
https://streetcomplete.app/p/337021.jpg
https://streetcomplete.app/p/337022.jpg