Lumber room

The phrase "lumber room" is found in British novels at least during the nineteenth century, and the use of the word lumber in this phrase is that found in many obsolescent turns of phrase heard in various English-speaking countries.

The large houses of the well-heeled of Britain commonly had much very old, well-built furniture in them, more than was to be used in every room at any given time. Every piece was made-to-order. When not needed, it was neither sold nor discarded by them. At least one out-of-the-way room was selected to store the pieces that weren't in use. This was called the lumber room. Such is what is alluded to in the definition in the OED, whose first reference is Richardson's novel Pamela and which is mentioned in a bit more detail in Daniel Pool's literary reference book of the 1990's, "What Jane Austen Ate and Charles Dickens Knew," among other literary reference works.

The OED mentions in the verb "lumbering" that it first meant to obstruct with pieces of wood to make things from, and then shifted to general obstruction, hence furniture fit the later meaning.

Trivia: The phrase "lumber room" is used in the book Murder at the Vicarage, by Agatha Christie, Chp.22., as well as in the first stave of "A Christmas Carol" by Charles Dickens. The term is also used in Sir Arthur Conan Doyle's Sherlock Holmes short story titled "The Adventure of the Six Napoleons," first published in The Strand, vol. xxvii, no. 161, dated May, 1904.