Two clocks run: the permit and the build. For a complete application, California requires a decision within 60 days, and as of November 2026 a completeness check within 15 business days. Design before that and construction after it take longer, and the lot, the plan and how fast corrections are answered decide the total.
Where does the time go?
- Lot check and design. Survey, layout, structural and energy work. Pre-approved plans can shorten this.
- Plan check. Submittal, completeness review, corrections and resubmittal.
- Utility work. Sewer, water and electrical capacity, sometimes with the utility on its own schedule.
- Construction and inspections. Foundation, framing, rough inspections, finishes, final.
What speeds things up?
- A complete first submittal, with the survey and utility routes worked out.
- A plan that already fits the setbacks and height limits.
- Quick answers to plan check comments.
- Choosing a conversion over new construction when the structure is sound.
San Jose notes
Complete preapproved submittals can be permitted the same day as plan review, which removes most of the permit wait. Custom plans follow the state deadlines. Factory-built units shorten the on-site build but add delivery and crane logistics.
Sources, as of November 2026: California Government Code section 66310 and following (ADU law), including SB 543 (2025); California Department of Housing and Community Development, ADU Handbook. General information, not legal advice. City of San Jose, "Preapproved ADUs".
Updated November 2026