lumber room

a room in a house used for storing odds-and-ends, especially old furniture.

Origin of lumber room

First recorded in 1735–45

So, after a short lesson, he proposed to go into the lumber-room and find something to work upon.

Put Yourself in His Place |Charles Reade
The Squire's room was empty, but the door into the lumber-room adjoining it was open, and the stifled sounds came through it.

Robert Elsmere |Mrs. Humphry Ward
His innovations are all made after visits to the lumber-room.

Painted Windows |Harold Begbie
For ourselves, after a miserable meal, we found a bed laid in an out-house, which also served for lumber-room and larder.

Early Western Travels, 1748-1846, Volume XII |William Faux

Yes, it looks like a lumber-room where they've stored all the odds and ends and litter of the house.

The Betrothal |Maurice Maeterlinck