You need a building permit with drawings, structural engineering and an energy-code report, plus electrical, plumbing and mechanical permits. The city has 15 business days to tell you whether your application is complete and 60 days after that to approve or deny it. Using the city's pre-approved standard plans can cut plan review to a few business days.
What goes in the set
Site plan, floor plan, elevations, sections, structural drawings and calculations, energy-code forms, and a plumbing and electrical layout. The City of Los Angeles publishes pre-approved standard ADU plans, and if one fits your lot it skips nearly all of the design review.
How long it really takes
The 60-day clock is a legal ceiling on a complete application, and it is real. What stretches the calendar is the correction cycle: the city sends comments back, you revise, you resubmit. A custom detached ADU commonly takes 8 to 14 weeks for a first review, a garage conversion 6 to 10 weeks, and each correction round adds a few more. A pre-approved standard plan can come back in 3 to 10 business days.
The single biggest thing you control is submitting a complete, clean set the first time. Everything else is the city's calendar.
The other approvals
Sewer capacity and connection permits. Utility applications if you want a separate meter, which run on the utility's schedule, not the city's. A grading permit on a sloped lot. Fire department review in a very-high fire severity zone. When it is all signed off, the unit gets its own address.
Los Angeles County figures, reviewed 2026-10-29 by America General Contractors, California contractor licence CSLB 1083262. Planning ranges, not a quote, and not legal advice. We confirm the current rules for your parcel before anything gets drawn.
Related questions
- How do I get a building permit in Los Angeles?
- What is Title 24?
- Can I build an ADU on my property in Los Angeles?
