The six phases of an ADU project
From "thinking about it" to a certificate of occupancy.
Most LA-area projects run 10 to 14 months end-to-end — slower in Pasadena and Santa Monica, faster with a pre-approved standard plan. Here's the sequence, in plain language.
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01
Feasibility & design intent
Walk the lot. Confirm zoning, setbacks, easements, hillside or coastal overlays. Pick a rough size and ADU type. Often paired with a free architect consult.
3–6 weeks -
02
Working drawings
Architect produces permit-ready plans — site plan, floor plans, elevations, structural notes, MEP schematics. Soils report and survey ordered if the lot requires them.
4–8 weeks -
03
Plan check & corrections
Submit to the city. State law caps the first review at 60 days, but most projects go through two or three rounds of corrections — that's where the real timeline lives.
6–12 weeks -
04
Permit issuance & pre-construction
Pay fees. Pull the permit. Line up the contractor's crew, financing draw schedule, and utility-coordination paperwork.
1–2 weeks -
05
Construction
Site prep, foundation, framing, MEP rough-in, drywall, finishes. Inspections happen at each gate. Detached ADUs typically run 5–8 months; garage conversions run 3–5 months.
4–8 months -
06
Final inspection & Certificate of Occupancy
Final building, electrical, plumbing, and (if applicable) fire inspections. Address punch-list items. Once the C of O is issued, you can legally rent it.
2–4 weeks
End-to-end: typically 10 to 14 months.
Start phase one this week.
Open your city's dossier or run the estimator — both are designed to compress phase one into an afternoon.