Housing units comprise houses, apartments, groups of rooms, or single rooms, which are occupied, or vacant but intended for occupancy, as separate living quarters. Specifically, there is a housing unit when the occupants live and eat separately from any other persons in the structure and there is either (1) direct access to the unit from the outside or through a common hall, or (2) in 1960, a kitchen or cooking equipment for the occupants exclusive use: in 1970, complete kitchen facilities for the occupants exclusive use.
Structures intended primarily for business or other non-residential use may contain housing units; for example, the living quarters of a merchant in back of his shop. Separate living quarters occupied by staff personnel (but not inmates) in institutions which meet the definitional criteria constitute housing units; as do separate living quarters of supervisory staff in dormitories, nursing homes, etc. Any separate living quarters, which meet the above criteria, in rooming or boarding houses are classified as housing units, as are entire rooming or boarding houses where there are four or fewer roomers unrelated to the person in charge. Trailers, tents, boats, railroad cars, hotel and motels occupied by usual residents which meet the definitional criteria constitute housing units; as do vacant rooms or suites in hotels where 75 percent or more of the accommodations are occupied by usual residents.