Hiring & process
How long does it take to build an ADU in California?
Door-to-door, a California ADU takes 9–18 months: 2–4 months of design and engineering, 2–4 months in permit review, and 4–10 months of construction. Garage conversions run shorter (5–8 months total); two-story detached builds the longest.
State law requires ministerial review for compliant ADUs, with a 60-day decision clock once a complete application is submitted. Real-world plan-check times vary 4–16 weeks depending on jurisdiction backlog and corrections cycles.
Construction time depends on lot access, weather windows, and trade availability. Foundation and framing dominate the first half; trades, drywall, and finishes the second.
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Related questions
- • How long does ADU plan check take in Los Angeles?
- • Can I speed up ADU permitting?
- • What's the typical garage conversion timeline?
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