Does state law override my city's ADU rules?
Largely, yes — for the baseline rules. Starting in 2017 and continuing through several rounds of legislation, California has set statewide minimum standards for ADUs that cities cannot make more restrictive. Cities can still set their own design standards, adopt their own objective development standards within state limits, and control things like architectural review in some cases — but they can't ban ADUs outright in single-family zones, and they can't impose rules stricter than the state floor described below.
What cities do still control: specific setback and height details within the state's outer limits, design/architectural standards, and how local staff interpret and process applications. That's why the same ADU project can move faster in one city than another even though both are bound by the same state law.
How fast must my city approve an ADU permit?
The 60-day rule
State law generally requires a city or county to approve or deny a complete ADU application within 60 days. If the city doesn't act within that window, the application is generally considered approved by default. This is one of the most homeowner-favorable pieces of California ADU law, and it's a major reason ADU permitting tends to move faster than permitting for a typical addition or remodel.
The 60-day clock applies to the ADU-specific ministerial review — it doesn't eliminate the time needed for plan preparation, corrections requested by the city, or any separate approvals your specific project might trigger (like a septic system or a coastal zone review). See our guide on common reasons permit applications get corrections or rejections for how to avoid losing time to avoidable issues.
Have an existing structure that was never permitted? See our guide on legalizing an unpermitted ADU — state law provides a real path for units built before 2020.
How big can my ADU be?
State law sets minimum sizes that cities must allow "by right," regardless of local floor-area-ratio limits that would otherwise restrict it:
- Standard ADU: at least 850 square feet for a studio or one-bedroom unit, and at least 1,000 square feet for a unit with two or more bedrooms, must generally be allowed.
- Junior ADU (JADU): capped at 500 square feet, and must be contained within or attached to the existing single-family home's walls.
Cities can allow larger ADUs than the state minimum, and many do — but they generally cannot restrict you to something smaller than these baseline sizes if your lot and project otherwise qualify.
Do I need extra parking for my ADU?
Often not. State law eliminates the parking requirement entirely for ADUs in several common situations, including when the ADU is within a half-mile of public transit, when it's a conversion of an existing structure (like a garage), or when it's within a designated architecturally or historically significant district. Where a parking requirement still applies, state law generally caps it at one space per unit or per bedroom, whichever is less restrictive, and allows that space to be provided in setback areas or as tandem parking in many cases.
Are there fee breaks for smaller ADUs?
Yes. Impact fees (the fees cities charge to fund infrastructure like roads, schools, and parks) are generally waived entirely for ADUs under 750 square feet. Larger ADUs can be charged impact fees, but only in proportion to the size of the primary home — not the same flat fee a new single-family home would pay.
Do I have to live on the property to have an ADU?
For a standard ADU, most California cities currently cannot require you to live in either the main house or the ADU as a condition of permitting it — that owner-occupancy requirement has generally been suspended at the state level, though this is an area of law that has shifted over time. For a Junior ADU specifically, owner-occupancy is more commonly still required in many jurisdictions. Because this detail changes and can vary by city, confirm the current owner-occupancy rule with your local planning department before assuming either way.
How many ADUs can one property have, and can an HOA block them?
These two questions come up often enough that we've covered them in dedicated guides: see how many ADUs you can build on one property for how conversion ADUs, detached ADUs, and JADUs can combine on a single lot, and can your HOA legally block an ADU for what protection state law does and doesn't provide if your property is HOA-governed.
Where to read the actual law
- California Department of Housing and Community Development's official ADU handbook and resources
- California Government Code Section 65852.2 (ADUs) and 65852.22 (JADUs), available on the California Legislative Information site
This is general information, not legal advice
This page describes general, statewide rules to help you understand the baseline homeowners are working with. It is not legal advice, and it doesn't cover every local ordinance, overlay zone, or exception that might apply to your specific parcel. Your city's planning department and a licensed contractor familiar with local requirements are the right sources for exactly what applies to your property.
Frequently asked questions
No. State law requires cities to allow ADUs on qualifying residential lots and prohibits outright bans, though cities retain some control over design standards and local processing details within the limits state law sets.
No — the 60-day rule applies to permit approval, not construction. Design, plan corrections, and the actual build still take additional time. See our cost and timeline guide for typical build timelines by ADU type.
The state minimums described here apply statewide, including across Los Angeles, Orange, San Bernardino and Riverside counties. Specific local processing steps and design standards still vary by city, so confirm details with your local planning department.