a storeroom

lumber room = die Abstellkammer, der Speicher --- EXAMPLE SENTENCE : They gave us a room that clearly had been a LUMBER ROOM before. (TripAdvisor online travel portal) --- A man should keep his little brain attic stocked with all the furniture he is likely to use, and the rest he can put away in the LUMBER ROOM of his library, where he can get it if he wants. (The Adventures of Sherlock Holmes: "The Five Orange Pips")