Process
How an ADU permit actually moves
The six stages between an idea and a building permit, which ones have a legal clock on them, and where the time really goes.
The short version
- Two stages have a legal deadline. The rest don't, and that's where projects stall.
- The city has 15 business days to tell you your application is complete, then 60 days to decide.
- Pre-approved plans cut the decision to 30 days. Every city has to offer them.
- The months go to correction cycles, not to the review itself.
State law puts a clock on parts of this and says nothing about the rest. Knowing which is which tells you where you can push and where you're just waiting.
- 01
Feasibility
What your lot allows, what your city allows, what your utilities can carry. No clock, since nothing's been submitted. Worth real time. Everything downstream is built on these answers.
- 02
Design and engineering
Floor plans, elevations, a site plan, structural calculations, and Title 24 energy compliance. No clock. The pace is yours, and a decision made here is cheap compared to the same decision made during framing.
- 03
Submittal
The application goes in. Since 2026 the city has 15 business days to tell you whether it's complete, and if they miss that, it's complete by default. Complete is a paperwork test, not an approval. It means the next clock can start.
- 04
Plan check
This is where a city reviewer goes through your drawings line by line. 60 days to approve or deny, or 30 if you used the city's pre-approved plans, which every jurisdiction has had to offer since AB 1332. In practice the first review comes back with corrections, you fix them, and it goes back in.
- 05
Permit issued
Fees get paid and the permit prints. If your project is over the impact fee thresholds, this is where those land, so nobody should be learning that number here.
- 06
Construction and inspections
Foundation, framing, rough plumbing and electrical, insulation, drywall, final. Each one scheduled with the building department. How quickly they can get an inspector out is a real constraint on your schedule, and it varies by city and by season.
Where the time actually goes
Not in the 60 day review. In the correction cycles around it. A submittal missing a detail comes back with comments, the comments take a couple of weeks to answer, and the resubmittal starts another round. Two or three rounds isn't unusual.
One round is achievable. The difference is almost entirely in what got checked before the drawings went in.
The other variable is which city you're in. The same set of drawings does not take the same time in two different jurisdictions, and the gap is wide enough to matter to your plans.
We won't give you a week count before we know your address and your scope, and you should be skeptical of anyone who will. Tell us both and we'll give you a realistic range for that jurisdiction instead of a best case.
Sources
- SB 543 (2025), 15 business day completeness determination
- AB 1332 (2023), pre-approved ADU plans
- California Government Code sections 66310 to 66342
This is our read of the rules, not legal advice. We write these because they're the questions we get asked, and we keep them current. ADU law changes most Januaries, and every city adds its own rules on top of the state's, so before you spend money on anything here, confirm it with your city or county planning counter. Or call us and we'll confirm it for you.
More guides
ADU law
What California ADU law lets you build
State law sets a floor your city can't go below. Here's what that floor is, what changed in January 2026, and which parts your city still controls.
Choosing
ADU, JADU, or garage conversion: which fits your lot
Four ways to add a unit, what each one costs you in constraints, and the questions that decide it before anyone draws anything.
Planning
Nine things to check before you spend a dollar
Site conditions decide more ADU budgets than design choices do. These are the ones that turn into change orders when nobody looks first.
Want this answered for your address?
State law is the floor. What your city allows on top of it is the part that decides your project. Tell us where you are and we'll tell you what fits.