California ADU rules and regulations 2021

New laws have made building ADUs (accessory dwelling units) easier than ever. Scroll down to see an overview followed by links to regulations in individual cities.

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To address the housing crisis, California legislators in 2020 and 2021 removed several restrictions around building ADUs and passed measures designed to actively promote construction

California ADU parking requirements

You do not need to build an additional parking space for an ADU if the ADU:

• Is located within a half mile of a public bus stop or rail station
• Is part of or within the primary residence or an existing building
• Is on a street that requires on-street parking permits, but the permit has not been offered to the occupant of the ADU
• Is located within one block of where a motor vehicle provides hourly and daily service as part of a regional fleet operated by a public agency or publicly leased motor-vehicle-sharing organization, or
• Is located within a historic district

California ADU setback requirements

The setbacks (minimum distance requirements) between structures or property lines are:

• Primary residence: 10 feet
• Side and rear property lines: 4 feet
• Front setbacks: Varies by city and zone

California ADU size limits

The maximum size is based on a few factors in addition to lot size:
• 426 square feet: The smallest unit allowed, per HUD requirements
• 800 square feet: Maximum size for one-bedroom unit (if within setbacks)
• 1,000 square feet: Maximum size for two-bedroom unit
Note: Certain cities allow for units up to 1,200 square feet.

See ADU rules for your city