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Vol. I ·California ADU Desk ·Licensed · Bonded · Insured ·CSLB #1098432 ·BBB A+ Accredited ·120+ ADUs Delivered ·Starting $250K ·10–16% ROI ·Los Angeles ·Bay Area ·Vol. I ·California ADU Desk ·Licensed · Bonded · Insured ·CSLB #1098432 ·BBB A+ Accredited ·120+ ADUs Delivered ·Starting $250K ·10–16% ROI ·Los Angeles ·Bay Area ·
GoldenStateADU

Permitting · 7 min read · March 28, 2025 · 322 words

The LA ADU permit timeline, week by week

From signed agreement to building permit in 14–22 weeks: what happens, who is doing it, and the three places projects stall.

Key takeaways

  • Lock financing (HELOC, cash-out refi, or renovation loan) by week 8.
  • Choose finishes by week 10 so material lead times don't push your construction start.
  • Notify neighbors by week 12 — courtesy goes a long way before trucks arrive.

State law caps LADBS' review of a compliant residential ADU at 60 days. In practice, the calendar from signed contract to permit-in-hand runs 14 to 22 weeks because the work that surrounds plan check — design, engineering, corrections — is what actually consumes the time.

Weeks 1–4: discovery and design development

The first month is interviews, site survey, soils report (if required), and a schematic design package. By end of week four you should have a floor plan, exterior elevations, a placement diagram showing setbacks, and a hard cost estimate within ±8%.

Weeks 5–9: construction documents and engineering

Construction drawings are produced in parallel with structural, Title 24, mechanical, electrical and plumbing calculations. This is where the most time gets compressed if your design team has done it many times — and where it expands by 4–6 weeks if they haven't.

Weeks 10–18: plan check (LADBS)

First-round plan check returns in 4–6 weeks for ADUs. Clean submittals clear in one corrections cycle; complicated lots take two or three. Hillside, historic overlay, and high fire-severity zone projects can extend this window by 4 weeks each.

Weeks 18–22: clearances and issuance

Once plan check approves, the permit moves to school district fee assessment, sewer capacity confirmation, utility coordination, and final fee collection. This is largely paperwork — but each clearance has its own queue and any one of them can add a week.

What you should do in parallel

  1. Lock financing (HELOC, cash-out refi, or renovation loan) by week 8.
  2. Choose finishes by week 10 so material lead times don't push your construction start.
  3. Notify neighbors by week 12 — courtesy goes a long way before trucks arrive.

FAQ · Permitting

Common questions on permitting

The questions readers send us most after this guide.

  1. What is SB-9 and does it apply to me?
    SB-9 (the California HOME Act) lets eligible single-family lots split into two parcels and/or add a duplex. We assess eligibility during the feasibility call — roughly 60% of LA single-family lots qualify on paper, fewer in practice once HPOZ, hillside, and coastal overlays are applied. SB-9 projects can stack with an ADU for up to four units on what was a single-family lot.
  2. What about hillside or coastal lots?
    Hillside requires a Methane District review (where applicable) plus a haul route plan if grading exceeds 1,000 cubic yards. Coastal Zone projects (anything west of Lincoln Blvd in Venice, for example) need a Coastal Development Permit on top of standard LADBS approval. Both are workable; both add 60–90 days.
  3. I'm in an HPOZ — can I still build?
    Yes, but with design review. Historic Preservation Overlay Zones require Certificate of Appropriateness from the cultural heritage commission before permits issue. We've shepherded projects through Miracle Mile, West Adams, Whitley Heights, and Spaulding Square HPOZs. Add 8–12 weeks for the COA process.
  4. How long does an ADU project take in Los Angeles?
    Most detached ADUs run 9–13 months from contract to certificate of occupancy. Garage conversions are typically 4–6 months. Permitting alone is usually 60–120 days at LADBS depending on whether we use a pre-approved standard plan or a custom design that needs full plan check.
  5. Can I move faster with a pre-approved standard plan?
    Yes — meaningfully. LADBS Standard Plan ADUs skip the design review portion of plan check and often clear permitting in 30–60 days instead of 90–120. We carry a curated library of standard plans from 480 to 1,200 sq ft.

Sources & further reading

  • California Government Code §65852.2 — statewide ADU framework (ministerial review, 60-day clock).
  • LADBS — Accessory Dwelling Unit information bulletins and current permit fee schedule.
  • HCD — California Department of Housing & Community Development, ADU handbook (2024 update).
  • Internal data: 120++ ADU projects delivered across Los Angeles County, 2018–2025.

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