Walk-in Closet Concerns: How Large for a Mezuzah?
A beis ha’otzar (a storage room) requires a mezuzah. According to most opinions, a brachah is recited when affixing amezuzah on a beis ha’otzar of requisite size. A garage—where a car or other possessions are stored—falls under this category.
The requirement of a mezuzah on a beis ha’otzar is due to the sporadic visits the owner makes to the room in order to store, retrieve or view their possessions. The shiur (minimum size) for any room to require a mezuzah, according to the letter of the law, is four by four amos(arm-lengths, i.e. a total measurement of six feet by six feet. See Halachah #671 for some parameters).
However, there is an opinion (cited by the Chamudei Daniel) that any room that is chazu l’tashmisho (suitable for its [particular] purpose) requires a mezuzah—even if it is smaller than the regularshiur. Some qualify that this would only apply to a smaller room of significance, i.e., one that is attached to a larger room. Accordingly, there are those with the minhag (custom) to be stringent with regard to walk-in closets, and place amezuzah even on the door of a space smaller than four by four amos—but it’s affixed without a brachah.
Even those who disagree on the designation of chazu l’tashmisho on a smaller walk-in closet, may still be of the opinion that it requires a mezuzah, since it’s an access door to the larger room, based on the psak (ruling) of Rav Akiva Eiger (and they affix it on the opposite side of the doorway).
On the other hand, a doorway of a closet that is too small to qualify as a walk-in closet is patur (exempt) from a mezuzah, according to most opinions. It should be noted that a closet or storage room that is a walk-through passage—of any size—is similar to a foyer, and would require a mezuzah, according to mainstreampsak.
There are other places on a Jewish property where the owner is not required to place a mezuzah: No mezuzah is affixed on a storage space for garbage—even if kept there only until it is permanently disposed of—and even if the place is not dirty or odorous (conditions that would preclude amezuzah otherwise).
A room in a home that holds people other than the primary residents is not considered the owner’s storage place. Therefore, affixing mezuzos to doors of rented units on our property are the responsibility of the tenants, and the room of a non-Jewish live-in worker does not need a mezuzah (unless their room is also used as storage for the Jewish owner’s personal possessions).
(For more information on mezuzahplacement see Halachah #67 for the requirements for a brachah; Halachah #169 on requisite room-size; Halachah #402, checking mezuzos in Elul;Halachah #422, mezuzah for renters. A search for “mezuzah” in the archives ofwww.halacha2go.com lists more related subjects.)