Guide · permit timeline
A California local agency has 60 days to approve or deny a complete ADU application, and if it misses the deadline the application is deemed approved by operation of law (Gov. Code § 66317). Most homeowners spend months in plan check without ever learning this clock exists, because the city has no reason to mention it.
“If the local agency has not approved or denied the completed application within 60 days, the application shall be deemed approved.”
Gov. Code § 66317(a) · verified against leginfo
Two words carry the weight. Completed: the clock runs from a complete application, and completeness is where cities recover the time the Legislature took away. Deemed: approval happens automatically, without anyone at the counter agreeing to it.
The same section requires the decision to be ministerial:
“shall be considered and approved ministerially without discretionary review or a hearing”
Gov. Code § 66317(a)(1) · verified against leginfo
No planning commission, no design review board, no neighbor notification. If your city schedules a hearing for a standard ADU, it is applying a process the statute forbids.
Homeowners who document their builds report the same pattern: the calendar time is not the 60-day review, it is everything around it. Three places the months actually go:
The completeness fight. An application is not complete until the city says it is, and each returned checklist restarts the wait. Ask for the completeness determination in writing and ask which items are outstanding, because the 60-day clock is only enforceable from that date.
Correction cycles. Plan checkers review against building code, energy code, and fire code, and almost no project passes on the first submittal. Each cycle adds weeks. The corrections must be objective code requirements: § 66323(b) precludes local design and development standards on by-right units, so “the roofline should match the neighborhood” is not a correction you have to accept.
Pre-existing conditions. Cities historically used an old fence or an unpermitted water heater to hold the ADU hostage. The statute now bars that:
“shall not deny an application for a permit to create an accessory dwelling unit due to the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that do not present a threat to public health and safety”
Gov. Code § 66322(b) · verified against leginfo
Gov. Code § 65852.27 requires every local agency to run a preapproved ADU plan program and to post the approved plans on its website. A preapproved plan has already been through plan check, which removes the correction-cycle loop entirely for the structure itself. HCD has cited cities for failing to operate the program, so if your city's website has no preapproved plans page, that absence is itself a compliance problem worth raising. Read § 65852.27 →
California reviews local ADU ordinances and publishes findings letters. Under Gov. Code § 66316, an ordinance found non-compliant is null and void in its entirety, and state standards apply instead. Of the city ordinances reviewed so far, most have failed. An extra submittal requirement or review step that exists only in a void ordinance is not enforceable, which makes your city's compliance status the first thing to check, not the last.
The rules above are the statewide floor. What you can build also depends on your jurisdiction's compliance status and your lot. The feasibility check resolves both and returns a size range with the governing section for every figure.