Permits · San Jose
ADU Permits in San Jose: Step-by-Step 2026 Guide
How the San Jose ADU permit process actually works in 2026, pre-approved plans, fees, timelines, and the gotchas that slow most projects down.
San Jose has the largest ADU permit volume in the Bay Area and one of the more navigable processes once you know the path. Here's the 2026 step-by-step.
1. Check pre-approved plans first
San Jose maintains a pre-approved ADU plans library at sanjoseca.gov. Using one of these designs cuts plan-check time from months to weeks because the structural and architectural review is already done. SHAPE's modular designs can be submitted as pre-approved equivalents.
2. Pull a feasibility check
Confirm setbacks, height, lot coverage, and any overlay zones (flood, hillside, historic). San Jose Planning offers a free pre-application meeting that catches 80% of issues before you spend money on drawings.
3. Permit fees
- Plan check + permit: roughly $8,000 – $14,000 for a typical 600 – 900 sq ft detached ADU.
- School fees: waived for ADUs under 750 sq ft. Over 750 sq ft, expect $3 – $5 per sq ft.
- Utility connection fees: $5,000 – $15,000 if a new sewer lateral or water meter is needed. None for ADUs under 750 sq ft on existing connections (state law).
4. Realistic timeline
- Pre-approved plan: 4 – 8 weeks to permit.
- Custom design: 3 – 5 months to permit.
- Hillside or special overlay: add 2 – 4 months.
5. The gotchas
Sewer capacity is the most common surprise, older East San Jose and Willow Glen sewer lines occasionally require a lateral upgrade. PG&E electrical service upgrades can also add 2 – 3 months if your panel is undersized. SHAPE checks both during the feasibility phase, not at permit time.
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