Colma City ADU regulations are contained in Chapter Five, Subchapter 5.19 of the Municipal Code.


5.19.070 Standards.

A. Except as provided in subparagraph (B), accessory dwelling units must meet the following standards:

1. Development on the Lot.

(a)  A single-family dwelling must exist on the lot or be constructed in conjunction with the accessory dwelling unit.

(b)  The accessory dwelling unit must be:

(i)  Detached from the existing primary dwelling, but located on the same lot as the existing dwelling;

(ii)  Attached to the existing dwelling; or

(iii)  Located within the living area of the existing dwelling.

(c)  Only one accessory dwelling unit shall be allowed per lot.

(d)  The accessory dwelling unit is not intended for sale separate from the primary residence.

2. Occupancy.

(a) The property owner must occupy either the primary dwelling or accessory dwelling unit.

(b) The accessory dwelling unit may be rented, but shall only be rented for terms longer than 30 days.

3.Building and Construction.

(a)  An accessory dwelling unit shall include permanent provisions for living, sleeping, eating, cooking, and sanitation.

(b)  An accessory dwelling unit is required to have fire sprinklers, only if the primary residence is also required to have fire sprinklers.

(c)  An accessory dwelling unit must receive the approval by either the North San Mateo County Sanitation District or South San Francisco Sewer where a private sewage disposal system is being used.

(d)  An accessory dwelling unit shall meet the requirements of the building code, as adopted and amended by Chapter 5, Subchapter 4 of the Municipal Code, that apply to detached dwellings, as appropriate.

(e)  A separate utility connection shall be installed directly between the accessory dwelling unit and the utility. The connection shall be subject to a connection fee or capacity charge, or both, proportionate to the burden of the proposed unit, based on either its size or the number of its plumbing fixtures, upon the water or sewer system.

(f)  No passageway shall be required in conjunction with the construction of an accessory dwelling unit. “Passageway” is defined as a pathway that is unobstructed clear to the sky and extends from to street to one entrance of the accessory dwelling unit.


(a) Except as provided in subparagraph (b):

(i) Accessory dwelling units must meet the following parking standards:

(I)  For accessory dwelling units with no separate bedrooms, one off-street parking space shall be provided per unit.

(II)  For accessory dwelling units with at least one separate bedroom, one off-street parking space shall be provided per bedroom.

(ii) If parking is required:

(I)  The required parking spaces may be located on setback areas approved by the City Planner or tandem parking on an existing driveway, unless specific findings are made under subparagraph (II).

(II)  Parking arrangements in subparagraph (I) may be prohibited if the City Planner makes specific findings that such parking arrangements are not feasible based upon specific site or regional topographical or fire or life safety conditions, or that such arrangements are not permitted anywhere in the jurisdiction.

(III)  When a garage, carport, or covered parking structure is demolished in conjunction with the construction of an accessory dwelling unit, the replacement spaces may be located in any configuration on the same lot as the accessory dwelling unit, including, but not limited to, as covered spaces, uncovered spaces, tandem spaces, or by the use of mechanical automobile parking lifts.


Colma City Website

Colma City Planning Department