Foster City Municipal Code Chapter 17.78 contains details of the ADU regulations.
Summary for Newly Constructed Accessory Dwelling Units:
In order to grant a permit to construct an accessory dwelling unit, the following findings shall be made by the community development director:
A. The accessory dwelling unit is located on the same lot or parcel on which the owner of record maintains his principal residence and consents to the recording of an owner-occupancy restrictive covenant (deed restriction) per subsection K of this section;
B. The primary residential unit, accessory dwelling unit and lot comply with existing zoning requirements including, but not limited to, minimum lot size, lot dimensions, setbacks, lot coverage, and building height; however, no additional setback shall be required for an existing garage that is converted to an accessory dwelling unit, and a setback of not more than five feet from each side lot line and a rear setback compliant with the provisions of this title shall be required for an accessory dwelling unit that is constructed above an existing garage;
C. The accessory dwelling unit meets the current Uniform Building Code as adopted by the city;
D. Only one accessory dwelling unit shall be allowed for each parcel;
E. Property owners within a three-hundred-foot radius have been notified of the proposal for an accessory dwelling unit;
F. Adequate sanitary services for the additional increment of effluent resulting from the accessory dwelling unit shall be regulated to the satisfaction of the city engineer;
G. Any exterior changes to the buildings on the property, front yard paving, fences, or other improvements regulated by the city have been reviewed and approved as required by Chapter 17.58, Architectural Control and Supervision;
H. All accessory dwelling units shall conform to the definitions set forth in Section 17.78.040;
I. The accessory dwelling unit is not intended for sale separate from the primary residence, but may be rented per the provisions of subsection J of this section;
J. Any accessory dwelling unit may be leased to a maximum of two paying guests, for a period not fewer than thirty consecutive days. If an accessory dwelling unit is constructed pursuant to all of the provisions described herein, the principal residence may be leased to a maximum of two paying guests for a period not fewer than thirty consecutive days. In no case shall both the principal residence and accessory dwelling unit on a lot be leased simultaneously;
K. Prior to obtaining a building permit for an accessory dwelling unit, an owner-occupancy deed restriction, approved by the city attorney, shall be recorded with the county recorder’s office, which shall include the pertinent restrictions and limitations of an accessory dwelling unit identified in this section. Said deed restriction shall run with the land, and shall be binding upon any future owners, heirs, or assigns;
L. The maximum floor area of an accessory dwelling unit shall not exceed six hundred forty square feet;
M. The minimum total area of floor space for any attached or detached accessory dwelling unit must comply with minimum size requirements as specified by applicable state law or building code and as may be modified by local ordinance;
N. No passageway shall be required in conjunction with the construction of an accessory dwelling unit;
O. An accessory dwelling unit located within the envelope of an existing primary residence shall not be required to provide fire sprinklers if they are not required for the primary residence and may employ alternative methods for fire protection. Notwithstanding the aforesaid, any detached accessory dwelling unit shall provide fire sprinklers as required by fire code and as may be amended by local ordinance;
P. Any accessory dwelling unit shall be located a minimum distance of ten feet from any dwelling existing or under construction on the same lot or any adjacent lot; and
Q. Any detached accessory dwelling unit shall be located within the rear half of the lot and comply with all other provisions of this title. (Ord. 611 § 3 (part), 2017)
A. Parking requirements for accessory dwelling units shall not exceed one parking space per unit. This space may be provided as tandem parking, including on an existing driveway or in setback areas, excluding the nondriveway front yard setback. Exception to the requirement for provision of one parking space may be made per subsection B of this section.
B. Parking is not required in the following instances:
1. The accessory dwelling unit is located within one-half mile of public transit, including transit stations and bus stops.
2. The accessory dwelling unit is located within the envelope of an existing permitted and legally constructed principal unit or within a permitted and legally constructed accessory building or accessory structure which is compliant with all relevant building, fire, and other applicable codes.
3. When there is an approved car share vehicle for which a Foster City business license has been issued and remains active located within one block of the accessory dwelling unit.
C. Replacement Parking. When a garage, carport, or covered parking structure is demolished or converted in conjunction with the construction of an accessory dwelling unit, replacement parking shall not be required and may be located in any configuration on the same lot as the accessory dwelling unit.
D. Except as contained herein, minimum parking capacity as required for the primary residence and accessory dwelling unit shall be maintained at all times consistent with the requirements of Chapter 17.62. (Ord. 611 § 3 (part), 2017)