City of San Mateo Law Library
City of San Mateo Municipal Code.

27.04.170 DWELLING UNIT.

"Dwelling unit" means one or more rooms in a residential structure which are arranged or designed for use by one family, plus not more than two paying guests, which includes provisions for living, sleeping, eating, cooking and sanitation, and if located on multiple levels/stories, the unit provides interior connections from a common living area (including the living room, family room, dining room, kitchen, and other common living areas as determined by the Zoning Administrator). In addition, a "primary residential dwelling unit" means a building or separate portion thereof designated and/or customarily used as a residence by not more than one family and situated on a parcel or lot on which no other primary dwelling is located. The primary residential dwelling unit shall be larger, in terms of floor area, than any other residential structure situated on the same parcel or lot.