ADU Building, Zoning, and Design Regulations for San Jose, CA

With recent updates to California’s ADU laws, San Jose is a great place to build an ADU and allows you to add significant value to your property. Before you start building, make sure you understand San Jose’s special use regulations for accessory dwelling units.


San Jose ADU Zoning Requirements

Zoning Regulations:

  • The lot for a proposed ADU must be zoned R-1, R-2, R-M of PD. ADUs can also be built on a lot designated in the General Plan as Downtown/Mixed-Use Neighborhood/Mixed-Use Commercial, Residential Neighborhood/Rural Residential/Transit Residential, or Urban Residential/Urban Village.
  • Single family properties: one ADU and one JADU is allowed per lot.
  • Duplex or multi-family properties: two detached ADUs are allowed. A duplex is allowed an attached ADU. For multifamily lots, a number of attached ADUs equivalent to up to 25% of existing units may also be allowed; for example, a building with 12 units may qualify for 3 attached ADUs. JADUs
    are not allowed.

Location Requirements for ADUs in San Jose

Single-family Properties:

  • Detached ADU Location: Must be in the rear yard or minimum of 45 feet from the front property line. Detached ADUs may be newly constructed or an existing detached garage or accessory building can be converted or attached to an ADU.
  • Attached ADU Location: Must share a wall with the main residence OR share a roof structure with the main residence and be separated by no more than 10 feet. If located in the front yard, the ADU front door cannot be on same street-facing façade as that of the primary residence.
  • JADU Location: Must be located entirely within the main home’s existing footprint.

ADU Setback Requirements

Setback requirements for single family properties in San Jose, CA are as follows:

Detached ADUs: 

  • Front property line setback: 45 feet
  • Rear/Side setback, ground floor: 3 feet; if less, fire mitigation may apply
  • Rear/Side setback, second story: 4 feet
  • Rear/Side setback if ADU exceeds 40% Rear Yard Coverage: 4 feet

2nd Story ADUs:

  • Rear/Side setback is 15 feet. For a second story detached ADU, exterior features such as decks, unenclosed entry landings and balconies located on the second floor of a detached ADU may not be located along building walls nearest to the rear and side property lines.

Maximum ADU Size for Single-Family Properties

Maximum Area:

  • Detached ADU square footage can be up to 1,000 sqft if on a lot less than 9,000 square feet. They can have a maximum square footage of 1,200 sqft on a lot 9,000 sqft or greater. *Subject to Rear Yard Coverage Rule.
  • Attached ADUs are limited to an 800 sqft maximum OR up to 50% of the primary residence area without exceeding 1,000 sqft on a lot less than 9,000 square feet OR up to 50% of the primary residence not exceeding 1,200 sqft if on a lot that is 9,000 sqft or greater. *Subject to Rear Yard Coverage Rule
  • JADUs have a 500 square foot maximum.

*Rear Yard Coverage Rule: The rear yard is the area from the rear property line to the rear of the main home, across the full width of the lot. Total coverage of the rear yard by structures may not exceed 40% of the rear yard OR 800 sf, whichever is greater. Structures include ADUs, accessory buildings, sheds, gazebos, or other structures.


Maximum ADU Height Requirements in San Jose, CA

Maximum Height on Single Family Properties:

  • One-story detached ADUs have an 18 foot maximum height.
  • Two-story detached ADUs are limited to a height of 24 feet.
  • If a JADU is on the property, the height is limited to a maximum of 16 feet.
  • Attached ADUs have the same height limitations as the main dwelling unit.
View All San Jose ADU Regulations

Custom ADU Builder in San Jose

Backyard Unlimited has helped our San Jose neighbors increase their liveable space and property values by adding accessory dwelling units to their properties.

Over the years, we have worked throughout the greater Silicon Valley area, installing ADUs and backyard structures in Pacifica, Fremont, and Cupertino.
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