Homeowners want one number. We cannot give you one that is honest. No agency publishes a typical start-to-finish schedule for ADUs in Los Angeles, and the numbers you see online come from builders and consultants. What we can do is show which parts of the timeline are set by law, which are set by you and your team, and which are not set by anyone.
LA ADU Guide is an information site. We do not design, permit or build ADUs. Confirm deadlines with your building department.
The parts of the timeline
An ADU project has five stages. Only one has a legal deadline.
| Stage | Who controls the time | Is there a legal deadline? |
|---|---|---|
| 1. Feasibility and design | You and your designer | No |
| 2. Plan check and permit | The building department, with limits | Yes, state law |
| 3. Corrections and resubmittal | You, your designer, the agency | Only as part of the 60 days |
| 4. Construction | Your contractor, weather, supply | No |
| 5. Final inspection and occupancy | The inspector, you | No set time |
What state law sets for the city
Gov. Code section 66317 sets two clocks for a complete application when a home already exists on the lot:
- Completeness. The agency must tell you in writing whether the application is complete "not later than 15 business days after the permitting agency received the application." If it does not, the application "shall be deemed to be complete."
- Decision. The agency "shall either approve or deny the application to create or serve an accessory dwelling unit within 60 days" of receiving a completed application. One reproduction of the statute says that if the agency misses it, "the application shall be deemed approved."
The completeness step comes from SB 543, effective January 1, 2026, according to a legal aid summary. We read the text on a third-party site, not the official one, so check section 66317 at leginfo.legislature.ca.gov. HCD has also noted in letters to cities that the statute can be read as "approve or deny," so do not treat a missed deadline as a permit in hand without legal advice.
Other points from the statute:
- If you ask for a delay, "the 60-day time period shall be tolled for the period of the delay."
- If you apply for an ADU together with a new home, the agency "may delay approving or denying" the ADU until the new home is decided.
- A secondary summary lists a shorter clock for detached ADUs that use a pre-approved plan. We could not confirm the text, so verify it before counting on it.
What the 60 days does not include
The clock covers the agency's review. It does not cover:
- the weeks or months you spend before applying, such as surveying the lot, getting plans drawn, and soils or structural work when needed;
- the time you take to answer a correction list. Each round of corrections is time on your side;
- outside approvals that may sit outside plan check, such as fire, coastal or historic review, depending on the lot;
- construction, which has no legal deadline;
- inspections after the permit is issued.
One consultant source says outside sign-offs can stretch a project to about nine months. Treat that as one anecdote, not a rule. LADBS itself does not publish a schedule.
Permit validity
The LADBS homeowner guide says that "if construction on your project does not start within six months of the issue date of the permit the permit expires and must be renewed before work can continue." It also says a permit "expires two years from the date of issue on construction that has not been completed." The ADU page lists the plan check application as expiring 18 months from the submittal date, per our earlier guide. These are LADBS rules for the city; other agencies differ. Confirm the current terms in LADBS's information bulletin for ADUs.
Ways to save time that are real
- A complete first submittal. The clock does not start on an incomplete file. Ask for the current checklist and match it item by item.
- A pre-approved design. LADBS says its Standard Plan Program shortens review and "permits are issued more quickly." It still checks site factors. See prefab and pre-approved plans.
- Fast answers to corrections. Reply with everything the reviewer asked for in one package.
- Early research. Learn your fire zone, hillside or overlay status before you design.
- Not changing the plan. LADBS says that if you vary from the plans, "re-approval of the plan is required."
Things that slow a project down
- Missing documents in the first submittal
- A lot with a fire, coastal, historic or hillside layer
- Soils or structural questions
- A design that needs a variance or a discretionary approval
- Utility questions, such as a sewer or water upgrade (see impact fees and utility connections)
- Unpermitted work on the property that must be resolved
Planning your own timeline
Ask each person on your team for dates, in writing, for their stage:
- [ ] Designer: when will the plan set be ready to submit?
- [ ] Agency: what is the current published or typical plan check turnaround for ADUs?
- [ ] Contractor: how long after permit issue can they start, and how long do they expect to build?
- [ ] Utility: how long to complete any connection or meter work?
- [ ] You: when will you reply to corrections?
Then add a buffer. Because we cannot source a typical build time, we do not give one. Contractors should tell you what they assume and what could change it.
Keep a log
Write down the date you submitted, the date you got the completeness notice, each correction letter, each reply, and the permit date. If a deadline in section 66317 passes, that record is what you will use to ask the agency for an answer. See ADU permit process in Los Angeles for the steps and plan check and inspections for what happens after the permit. State rules are in California ADU rules.
This page is general information, not legal advice.
For median permit and CofO times by year, type and area, see What 41,000 LA ADU permits show about size, declared cost and time.