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Campbell ADUs

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Campbell ADU Guidelines Last Updated 01/26/21

The city government of Campbell has updated its local zoning codes to comply with the State ADU mandate.
The California Building Code (CBC) 2019 is adopted.


City Hint: The city permitted a total of 13 ADU projects in the past year of 2019, which makes it above average for ADU production compared to other cities statewide.

Number of ADUs allowed:

According to state law, all single-family homes are allowed at least one Accessory Dwelling Unit. Additionally, single-family lots which are owner-occupied may create one Accessory Dwelling Unit and one Junior Accessory Dwelling Unit. Also, multi-family lots may now add one ADU per every four existing residential units, so long as they were legally established.

Types of ADUs allowed:

Detached ADU, Attached ADU, Junior ADU are approved. ADUs may be new construction or converted from existing space. JADUs must be converted from existing space.

Lot size:

ADU projects on single family or multi-family residential properties will not be subject to the minimum lot size of the underlying local zoning code or by special ordinance. ~ According To AB68

ADU size:

Single-family and multi-family Parcels will be approved to create up to 850 sq. ft. for a one bed ADU or up to 1,000 sq. ft. for a two bed ADU, regardless of the underlying zoning standards of the property. A Junior Accessort Dwelling Unit (JADU) up to 500 sq. ft. is approved. The minimum size of any living unit (including ADUs and Junior Accessort Dwelling Unit (JADU)s) is 150 sq. ft. according to California Residential Code. ~ Updated: State Law AB-68


The maximum required setback for a detached new construction Accessory Dwelling Unit (ADU) shall be no more than 4 ft from the rear and side property lines. Setbacks will not be required for Accessory Dwelling Unit (ADU)s and JADUs converted from existing space that was legally eastablished. Attached Accessory Dwelling Unit (ADU)s and conversions from existing space to be expanded will be required to comply with the setbacks of the underlying zone. ~ Updated: State Law AB-68


Replacement parking shall not apply to properties which convert an existing garage to an Accessory Dwelling Unit or Junior ADU. ~ AB68 & AB881 Update

Fire Safety:

Per state requirements.

Shape, materials and style:

Design. A detached accessory dwelling unit shall be constructed to incorporate the same or similar building materials and colors as the primary dwelling unit, except for manufactured homes which shall be required to incorporate only the same or similar building colors as the primary dwelling unit. Attached or interior accessory dwelling units shall maintain the appearance of the primary dwelling unit as that of a single-family dwelling. Garages that are converted to accessory dwelling units shall include removal of garage doors which shall be replaced with architectural features, including walls, doors, windows, trim and accent details that remove any appearance that the structure was originally a garage.


Maximum height and stories. A detached accessory dwelling unit shall be a maximum of fourteen feet in height and not exceed one story. An attached or interior accessory dwelling unit shall be limited to the ground floor or the basement of the primary dwelling unit.

Design review:

General requirements. Except as otherwise specified by this Chapter, all accessory dwelling units shall satisfy the requirements applicable to a primary dwelling unit, including required yards, building height, distance between buildings, setbacks, floor area RATIO, and lot coverage standards, as specified by the zoning district and/or area or neighborhood plan in which the parcel is located, as well as all applicable general performance, site development, landscaping, and parking standards (including those specified by Section 21.23.040.H). The requirements for accessory structures found in Section 21.36.020 (accessory structures) do not apply to accessory dwelling units.

The City shall issue a building permit for an accessory dwelling unit that is consistent with the provisions of this Chapter, as determined by issuance of a Zoning Clearance, within one hundred twenty days of submittal of a complete building permit application. However, physical expansion (i.e., addition) or exterior alteration to an existing primary dwelling unit located on a parcel that is subject to design review pursuant to Chapter 21.42 (Site and architectural review) or Chapter 21.33 (Historic preservation) shall first receive approval of the appropriate land use permit prior to a submittal of a building permit application for an accessory dwelling unit.

Number of Bedrooms:

Allowable rooms. Accessory dwelling units shall include no more than two bedrooms.


Between between 2020 and 2025, owner occupancy requirements will not apply to new Accessory Dwelling Unit (ADU)s. (applicable to new construction and conversion units) ~ SB-13

Utility connections:

Utilities. The Building Official shall coordinate with local utility agencies to ensure that accessory dwelling units are not considered new residential uses for the purpose of calculating local agency connection fees or capacity charges for utilities, including water and sewer services.


Exception to parking requirement. The parking requirement for an attached and detached accessory dwelling unit shall not apply in the following instances, which shall allow creation of an attached or detached accessory dwelling unit without provision of additional parking.
The accessory dwelling unit is located on a parcel within a traversable distance of one-half mile of public transit.
The accessory dwelling unit is located on a parcel within a designated historic district.
The accessory dwelling unit is located within the boundaries of a permanent residential parking permit program, and where the City does not offer parking permits to the occupant(s) of the accessory dwelling unit.
The accessory dwelling unit is located on a parcel within one block of a City-licensed car-share vehicle (as defined by the California Vehicle Code).


Entrances. An accessory dwelling unit shall include separate exterior access from the primary dwelling unit and may include an interior connection. However, the front door of an accessory dwelling unit shall not be oriented towards a public street. A passageway from the accessory dwelling unit to a public street may be created, but shall not be required by the City.

Allowed Zones:

*** Beginning in 2020, according to state law, all residential zoning districts, including single-family and multi-family, are allowed to build Accessory Dwelling Units. ***

Zoning district. A parcel located within an R-1 (Single-Family Residential) Zoning District.


Existing primary dwelling unit. A parcel that is presently developed with one primary dwelling unit. An accessory dwelling unit may not be constructed on a parcel without a primary dwelling unit or which is developed with more than one primary dwelling unit.

Existing garages. An existing garage that is fully (not partially) converted to an accessory dwelling unit is subject to all provisions of this Chapter except that no additional setback from property lines or to other existing structures shall be required, provided that the existing garage is not expanded. Any expansion of the structure shall comply with applicable setback requirements and shall not be permitted to exercise the setback exception for non-conforming structures provided for in Section 21.58.050.F (Exceptions).

Demolition of an existing garage. When an existing garage (or carport) is demolished in conjunction with the construction of an accessory dwelling unit, any required parking spaces contained within the garage (or carport) shall be replaced concurrently with creation of the accessory dwelling unit. The replacement spaces shall comply with all applicable development standards except that the replacement spaces may be located in any configuration on the parcel, including, but not limited to, as covered spaces, uncovered spaces, or tandem spaces, or by the use of mechanical automobile parking lifts.

Kitchen / Bath:

Two bathrooms. In no case shall an accessory dwelling unit include more than one kitchen.

Building Code:

Building code. Accessory dwelling units shall comply with all applicable Building and Fire Codes as appropriate, except that the Building Official shall not require installation of fire sprinklers for an interior accessory dwelling unit if they would otherwise not be required for the primary dwelling unit, except if the creation of the accessory dwelling unit would result in creation of a "new dwelling using portions of the original structure" pursuant to Chapter 18.32 (Determination of scope of work).

Residential Building Code:

The California Building Code (CBC) 2019 is adopted.

Campbell City Planning Offices

Campbell Planning Division

70 N First St. Campbell, CA 95008 Campbell, CA 95008

Call/Text ADU Operator (408) 752-5614
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ADU Model 560 sqft

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Customer Reviews

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Detached ADU - Completed in 2020
1,003 sq. ft., 3 bed, 2 bath

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Costs / ROI



* upon completion of ADU


* based on local average price per sqft


* estimated by location


* 30 years / 5% interest rate / 20% down payment


Size: 500 sqft


Appreciation Estimate = (Base Value: $) / (Home's Living Space: sqft) * (ADU's Living Space: sqft)

Rental Estimate = (Rent Per Sqft: $4.27) * (ADU's Living Space: sqft)

Check your property's zoning, browse designs & get contractor estimates for your ADU project:

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