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Campbell, California: ADU Regulations

City or County:

Campbell, California

Date Updated:



All residential or mixed-use districts

Types of ADUs:

Attached, Detached, Garage Conversion
Junior ADUs


Single story for Detached

An Attached ADU be 2 stories, but only if primary home is 2 stories.

Lot Size:


Maximum ADU Floor Area:

Attached, Detached, Conversion: 1,200 SF
Junior: 500 SF

Note: in no case shall living area for attached or interior ADU exceed 50% of existing primary dwelling unit.

Lot Coverage:

Must comply with standards of underlying zoning district.


Max. 2 bedrooms


Max 120 SF closets


Max 1 kitchen (with permanent provisions for cooking and eating)

Junior ADU: Only efficiency kitchen permitted


Max. 2 bathrooms

Junior ADU: May be shared with primary home or another ADU, but may also have its own bathroom that counts against 500 SF max size

Note: Drainage and sewer connections should be assessed on a project by project basis.


Only newly-constructed ADUs require parking. Garage conversions do not.

    Junior ADU: none required

    Uncovered parking spaces required for accessory dwelling unit may encroach into required front-yard or street-side yard setback within existing driveway that satisfies the min. stall dimensions for a residential parking space, unless such configuration is determined not to be feasible based upon fire and/or life safety conditions present on property.

    State parking exceptions apply (public transit, historic district, no permits for ADU occupants, car share, attached/conversion/junior).


    Front- Same as primary home
    Interior Side- 4’
    Street Side- 12’
    Rear- 4’

    Building Separations:

    Behind- 10’
    Front- 10’
    Side- 5’

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


    Attached: must comply with standards of underlying zoning district.

    Detached: single story 16' max


    Attached or interior ADU limited to the ground floor or the basement of the primary dwelling and must maintain appearance of primary dwelling as that of a single-family dwelling. Spacing between structures and lot coverage guidelines of zoning district apply.

    Rear Yard Coverage:

    Must comply with maximum allowable yard coverage of zoning district.


    Detached must incorporate same or similar building materials and colors as primary dwelling, except for manufactured homes, which are required to incorporate only same or similar building colors as the primary dwelling.

    ADUs converted from garages to include removal of garage doors, to be replaced with architectural features that remove any appearance that structure was originally a garage.

    Note: Historically designated properties are only limited to interior or detached ADUs, with 1 story, 16’ in height, located behind the primary home and designed to match the primary home.


    Must include separate exterior access from primary dwelling. Front door cannot be oriented towards public street.

    Code Source:

    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!