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San Ramon, California: ADU Regulations

Date Updated:


Are ADUs allowed in San Ramon:



RC, HR, RE, RS, RM, RMH, and PD

Number of ADUs allowed:

ADUs are limited to one per primary dwelling.

Types of ADUs allowed:

Detached and attached ADUs are permitted.

Lot size:

Refer to state minimum requirements.

ADU size:

Both attached and detached ADUs must be a minimum of 150 sq. ft. in size. Attached units can be no more than 50% of the habitable area of the existing primary dwelling and are limited to 1,200 sq. ft. A detached unit also is limited to 1,200 sq. ft. in size.


2 bedroom max.


Must provide provisions for sanitation. 

2 bathroom max.


In all R zones or a PD zone, attached ADUs must conform to the setbacks applicable to the underlying residential zone. In the RS-6 and RS-7 zones, a detached one-story secondary unit must be set back at least 20 feet from the front property line, five feet from the interior side property lines, seven feet from the corner side property line, and seven feet from the rear property line. In all other R zones or a PD zone, the same setbacks apply with the exception of a setback of seven feet from the interior side property lines.

Note: Fire Department regulations should be assessed on a project by project basis.


A single additional parking space in the driveway generally meets the parking requirements for ADUs.

Fire Safety:

Refer to the state minimum requirements.

Shape, materials, and style:

Building materials, colors and exterior finishes should be mostly the same as those on the existing dwelling and be harmonious with the rest of the neighborhood. ADUs shall be designed to minimize potential privacy issues with the neighboring properties, and additional landscape screening may be required


Outside access to the ADU shall not be in the front of the existing dwelling. Side or rear access shall not be visible from the front or street.


Should follow guidelines to residential construction in the applicable zone.

Design review:

Must follow ministerial review per state standards.

Note: Historic Neighborhoods or Districts should be assessed on a project by project basis.


Either the main dwelling or ADU must be owner-occupied.

Allowed Zones:

ADUs are allowed in the RC, HR, RE, RS, RM, RMH, and in PD zones for residential uses on lots with existing or planned single-family dwelling.

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Important Note: Rules and regulations are updated and changed frequently. It’s one of our jobs to be up to speed and navigate those regulations. Let us know if our website isn’t up to date or if you have any information that could help. Cheers!