Additional ADU Requirements

ADU Parking Requirements


SMMC 27.19.50 (1-d)



To construct an ADU, a (20 feet in width, 18 feet in depth) parking space is required for every bedroom located within an ADU, unless the property meets parking exemptions.

Type of parking spaces include: garage parking spaces, carport parking spaces, uncovered parking spaces, or tandem parking spaces.

Parking Exemptions include (but not limited to):

  • ADU is within a ½ mile of public transit stop (bus stop, train station, and paratransit).
  • ADU is part of the existing legally permitted primary residence or an existing legally permitted ADU.
  • ADU is in an architecturally and/or historically significant district.
  • ADU is in an area with residential parking permit rules that do not offer permits to occupants of the ADU.
ADU Parking Requirements
The example* above shows a standard R1-B and R1-C zoning district lot with the required rear yard setback of 15 feet and side yard setbacks of 5 feet.

*A single family residence converting their garage into an Accessory Dwelling Unit (ADU.)

Utility Connections


A separate water, sewer service, or power service connection is not required. ADUs are not considered new residential units for calculating City connection fees or capacity charges for utilities. 

Deed Restriction (27.19.060)


 A deed restriction shall be recorded and submitted to the City of San Mateo prior to Building permit issuance which indicates the following:

  • The approved size and attributes of the accessory dwelling unit.
  • Only one unit may be occupied solely by person(s) other than the owner(s) on record.
  • If an accessory dwelling unit is rented, the unit shall not be rented for a period of less than 30 consecutive calendar days.
  • Sale of the accessory dwelling unit separately from the sale of the single-family residence is prohibited.