Two things stand between your plans and a finished ADU: plan check, which happens on paper before you build, and inspections, which happen on site while you build. This guide explains both in the City of Los Angeles, using the Department of Building and Safety's own wording where we have it. Other cities and the County work the same way in outline but with their own forms.
LA ADU Guide is an information site. We do not prepare plans or inspect work. Confirm each step with your building department. The older permit overview is in ADU permit process in Los Angeles.
Part 1: Plan check
Plan check is a review of your drawings against the building, residential, green and zoning codes. For ADUs, LADBS says plan check, permit issuance and inspections are all required. Under Gov. Code section 66317 the agency must decide a complete application within 60 days. State law treats the review as ministerial, meaning a check against fixed standards.
What reviewers look at
LADBS describes its review as checking for "compliance with local codes and ordinances." For an ADU that usually means:
- zoning: setbacks, height, size and lot rules
- structure and foundation, including soils where needed
- life safety: egress, smoke alarms, fire separation and sprinklers
- plumbing, electrical and mechanical systems
- energy and green building documents (see ADU solar and energy code)
- fire zone construction notes, where the lot is mapped (see ADUs in fire hazard zones)
Corrections
Getting a correction list is normal. LADBS says the permit is issued "once compliance with the listed corrections is verified." Treat corrections as a checklist:
- Read each item and mark who answers it: designer, engineer or you.
- Revise the drawings. Do not only write a reply letter.
- Resubmit every sheet that changed.
- Keep every letter and every revised set.
The state clock stops running while you have the application, and it can be tolled if you request a delay. Slow replies add time on your side. See how long an ADU takes.
Standard plans
A design already approved under the LADBS Standard Plan Program goes through a faster review. LADBS says the design is pre-approved for "building, residential, and green codes," but the department "will check that it fits your property." See prefab and pre-approved ADU plans.
Part 2: Inspections
Once the permit is issued, you or your contractor schedule inspections. The LADBS homeowner guide says to "call for inspection before covering any work." Do not pour, frame in or close up a stage until the inspector has signed off.
How to request one
- The guide gives 311 as the customer line, and says to call "at least 24 hours in advance." It also notes that workload can delay an inspection by another 24 hours. Online scheduling may exist, so ask what LADBS currently offers.
- Keep the Building Card (B-8) and the approved plans on site. The guide says "an inspection cannot be made without them."
- If the inspector finds a problem, the guide says a correction notice is left on site. Make the corrections and call again.
Stages in the homeowner guide
| Stage | When to call |
|---|---|
| Groundwork | Footing excavations are ready, with reinforcing steel, forms, and groundwork plumbing and electrical in place, before any concrete is poured |
| Rough | Framing is complete and plumbing piping, electrical wiring and heating ducts are installed in the framing, before anything is covered |
| Final | Work is complete: exterior surfaces painted or sealed, weather-stripping installed, fixtures installed |
This is the guide for single-family construction in general. An ADU permit can list more inspections, for example for fire sprinklers, energy items, a retaining wall or a separate utility. Read the permit card or ask the inspector for the list that applies to your project.
Final inspection
The guide says that at final, smoke detectors must be installed in bedrooms and in the hallway leading to bedrooms. Interior paint and carpet do not need to be finished. For an ADU you will also want the energy and sprinkler items closed out.
Certificate of Occupancy
LADBS says "in some cases" the department sends a Certificate of Occupancy after the final is signed, and "not all construction work receives a Certificate of Occupancy." Ask your inspector if your ADU will get one. Keep it, and the Building Card, as proof of inspection. Do not let anyone move in before the final sign-off.
Garage conversions
The homeowner guide says a converted garage requires provision of replacement parking before a Certificate of Occupancy, for general single-family work. State law, however, bars cities from requiring replacement parking when a garage is converted for an ADU, as the HCD Handbook explains. If the department raises it, ask which section it relies on. See ADU vs. JADU vs. garage conversion.
Permit expiration
The guide says a permit expires if work "does not start within six months of the issue date," and "two years from the date of issue on construction that has not been completed." Renew before it lapses.
Changing the design mid-build
LADBS says "If you have to vary from your plan specifications during construction, re-approval of the plan is required." Tell the plan checker before you change walls, windows, heights or systems.
Checklist
- [ ] Plans prepared by a qualified professional and signed where required
- [ ] Complete submittal, matched to the LADBS checklist
- [ ] Correction letters answered with revised sheets
- [ ] Permit card and approved plans on site
- [ ] Each inspection requested before work is covered
- [ ] Sprinkler, energy and utility sign-offs tracked
- [ ] Final inspection passed before occupancy
- [ ] Certificate of Occupancy, B-8 card and plans stored together
If something goes wrong
Ask the inspector to point to the code section. The guide says the department has an appeal process for alternate methods, and staff supervisors are in each office. Discuss concerns with the plan check engineer at the start.
For general rules, see the permits hub and California ADU rules. This page is general information, not legal advice.