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San Ramon, California: ADU Regulations

Date Updated:



All single- and multi-family zones (R and residential PD). 

Number of ADUs allowed:

For single-family, max one ADU and one JADU per lot. For multi-family, 25% of all existing units for ADUs within existing structure, plus two Detached, per lot.

Types of ADUs allowed:

Attached, Detached, Conversion, Junior



Lot size:


ADU size:

Attached/Conversion: At least 150 sq.ft., but not more than 50% of the net floor area of the existing dwelling up to a maximum of 850 sq.ft.
Detached: For all units, 150 sq.ft. minimum. For one bedroom and studio, max 850 sq.ft. For more than one bedroom, max 1,000 sq.ft.
Junior: Max 500 sq.ft.

Lot coverage:







Must provide provisions for eating and cooking. Junior ADU must provide efficiency kitchen.


Must provide provisions for sanitation. Junior ADU may share sanitation facilities with primary residence.


Attached: must conform to the setbacks generally applicable to residential development in the applicable zone.
Garage Conversions: 4’ side and 4’ rear max
Detached (non-garage): 4’ side, 4’ rear, 20’ front

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


An ADU shall require that one covered or uncovered parking space be provided in addition to the parking required for the primary unit. The additional space shall not be located within a required front setback. When a garage, carport, or covered parking structure is demolished with the construction of an ADU, off-street parking places shall be replaced. Exceptions:
ADU is located within one-half mile of public transit
ADU is located within an architecturally and historically significant historic district
ADU is part of the existing primary residence or an existing accessory structure
When on-street parking permits are required, but not offered to the occupant of the ADU
When there is a car share vehicle located within one block of the ADU


Attached: as generally applicable to residential construction in the applicable zone.
Detached: 16’ Max


The exterior design shall be in harmony with the immediate neighborhood. Building materials, colors and exterior finishes should be substantially the same as those on the existing dwelling. ADUs shall be designed to minimize potential privacy issues with the neighboring properties, and additional landscape screening may be required.

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


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.


Utility connections shall be required based on the service provider’s standards for ADUs

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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!