The short answer: The ADU permit timeline is set by law: a California city has 15 business days to tell you whether your ADU application is complete and 60 days to approve or deny it once it is. In practice, the only published dataset we found, covering 2018 to 2022, shows average waits of about 100 to 260 days, depending on the county and whether the lot sits in the coastal zone. The gap between the legal clock and the real one is where most homeowners lose months.
Last verified: October 2, 2026 · Written by the ADU Scope editorial team
Key fact: the 60-day clock starts only when your application is complete. A city that sends an incomplete notice, and an applicant who needs time to fix it, can stretch a “60-day” permit into many months without anyone breaking the law.
The ADU permit timeline: what state law promises
California’s ADU rules put two deadlines on every city. The state housing agency’s handbook (March 2026) cites Government Code § 66317 for both.
- 15 business days: the city must decide whether your application is complete and send written notice. If the notice is “incomplete,” it must list what is missing and how to fix it.
- 60 days: after a complete application, the city must approve or deny it. Review is ministerial, meaning staff check the plan against the code and have no discretion to reject a compliant design.
If the city misses the 15-business-day deadline, the application is deemed complete. If you disagree with an incomplete notice or a denial, you can appeal, and the city owes you a final written decision within 60 business days of the appeal. If you ask the city for more time, the 60-day period pauses for the length of the delay.
Some cities also write a “deemed approved” rule into their own ordinance. Los Angeles’s ordinance, for example, says an application is deemed approved if the city has not acted within 60 days. Check whether your city’s ordinance says the same.
What the data shows on the ADU permit timeline
The best public data comes from the Terner Center at UC Berkeley, which analyzed the annual progress reports cities file with the state housing department. It measured the average days from application to permit approval for 2018 to 2022.
| County | Inside the coastal zone | Outside the coastal zone |
|---|---|---|
| Los Angeles County | 260 days | 147 days |
| Orange County | 233 days | 101 days |
| San Diego County | No statistically significant difference between zones |
Attention: these numbers are averages from 2018 to 2022, before several recent state laws. The researchers could identify both an application date and a permit date for only about 29,000 of roughly 60,000 ADU projects, and they warn the usable records may be biased. Treat them as a rough historical benchmark, not a prediction for your city: they are averages, they predate recent state laws, and some projects may be missing from the data.
We did not find a published, city-by-city ranking of current ADU approval times. Beware of guides that quote precise numbers for a specific city without naming a data source.
Why the real ADU permit timeline runs longer than the law
The 60-day rule covers only one stage. Several things sit outside it.
The completeness loop
The clock for approval does not start until the city says your application is complete. Each incomplete notice sends you back to your designer, and resubmitting restarts the review. A missing structural detail or a forgotten form can cost weeks, even though the city is within its 15-business-day window every time.
Time you ask for
If you request a delay, the 60-day period is paused for that delay. That is fair, but it means your own revisions count against the calendar and not against the city.
Other approvals that run separately
Some cities run planning review separately from the building permit. Sacramento does not require it up front: its ADU guide says no separate planning or zoning approval is needed before you submit a building permit application, though an optional zoning review is available. Utility approvals, school fee payments and special reviews sit on top of that.
Coastal and special areas
Coastal lots add a coastal development permit. Under AB 462, effective October 10, 2025, the city or the Coastal Commission must approve or deny that permit within 60 days of a complete application. The handbook adds that an application is deemed approved if the Coastal Commission does not act within that window on a lot with an existing primary dwelling. The Terner data shows why this matters: in Los Angeles and Orange counties, coastal-zone applications averaged more than 100 days longer.
How to shorten your ADU permit timeline
- Ask for a pre-application meeting. Confirm setbacks, unit type and overlays in writing before you pay for plans.
- Use the city’s pre-approved plans if they fit. San Diego, for instance, gives pre-approved plans a 30-day review period. See Pre-Approved ADU Plans: Cities That Offer Free Plans.
- Submit a complete package. Use the city’s checklist and ask staff to confirm it before filing.
- Answer incomplete notices in one round. Collect every item the city lists and resubmit once.
- Keep a log. Note the date the city received your application, the date of each notice and every request for delay. You will need it if you appeal.
Tip: email your planner after filing and ask them to confirm the date your application is considered complete. That date starts the 60-day clock.
What to do if the city misses a deadline
- Check your records: when was the application filed, and has the city sent a written completeness notice?
- If 15 business days have passed without written notice, the application is deemed complete. Say so in writing and cite Government Code § 66317.
- If the 60 days have passed, ask in writing for the decision and quote your city’s ordinance if it has a deemed-approved rule.
- Use the city’s appeal process, then contact the state housing department’s ADU resources. HCD offers technical assistance on state ADU law and can review local ordinances for compliance.
FAQ
Does the 60 days include construction?
No. It covers only the city’s decision on your application. Design before it and construction after it are separate.
Can the city deny my ADU after 60 days?
If the application complies with the code, the review is ministerial and the city has no discretion to reject it. A denial must come with a full list of defects and how to fix them.
Do these timelines apply outside California?
No. They come from California law. Other states set different rules. See ADU Laws by State: Where You Can Build in 2026.
Do garage conversions go faster?
The legal deadlines are the same, but conversions are simpler to review. We could not find data that compares the two.
Next steps
- California ADU Laws 2026: What Changed and What You Can Build
- ADU Permit Cost by City: California Fees Compared
- Garage Conversion to ADU in California: Permits, Parking and Conversion vs. New Detached ADU
- Los Angeles ADU Rules: Setbacks, Size Limits and Permit Timeline
- San Diego ADU Rules and Fees Explained
- San Jose ADU Requirements: Complete Permit Guide
General information, not legal advice. Local rules vary and change; confirm with your planning department.
Sources: HCD ADU Handbook, March 2026 (PDF) · Terner Center, Comparing ADU Permitting Time Inside and Outside the Coastal Zone · Los Angeles City Planning, ADU Ordinance · City of San Diego, Information Bulletin 400 · City of Sacramento, ADU Application Submittal