San Jose has seen rapid ADU growth driven by Silicon Valley housing demand. The city follows CA state law closely and has added local incentives to encourage ADU construction.
Zoning & Size Requirements
| Allowed Zones | All residential zones (R-1, R-2, R-M, R-MH) |
| Max Size (Detached) | 1,200 sq ft |
| Max Size (Attached) | 1,200 sq ft or 50% of primary dwelling |
| Max Size (JADU) | 500 sq ft |
| Max Height | 25 ft for detached |
| Max Units | 1 ADU + 1 JADU |
Setback Requirements
| Rear Setback | 4 ft |
| Side Setback | 4 ft |
| Front Setback | Per underlying zone |
| Parking Required | No parking required |
| Owner Occupancy | Not required |
| Min Lot Size | No minimum |
Permit Process & Fees
| Approval Process | Ministerial review |
| Review Timeline | 60 days |
| Permit Fees | $4,000-$14,000 |
| Impact Fees | Waived for units under 750 sq ft |
| Plan Check | Standard review process |
| Pre-Approved Plans | Limited pre-approved options available |
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Construction Costs
| Average Build Cost | $180,000-$400,000 |
| Cost per Sq Ft | $250-$450 |
| Garage Conversion | $100,000-$220,000 |
| Prefab ADU (Installed) | $130,000-$300,000 (installed) |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders in minutes.
Compare ADU Financing Options →Rental Income Potential
| Avg Rent (1 Bedroom) | $2,000-$2,800/mo |
| Avg Rent (2 Bedroom) | $2,500-$3,500/mo |
| Short-Term Rental | Restricted; requires transient occupancy tax registration |
| Est. Annual ROI | 5-9% annual return |
Explore Prefab ADU Options
Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half. Compare top prefab manufacturers.
Compare Prefab ADUs →Recent Law Changes
What's Changed Recently
- SB 1211 (Jan 2025): Multifamily ADU expansion
- AB 1033 (2024): Separate sale provisions
- City ADU fee reduction program (2024)
- Expanded ADU resource center online (2024)
Tips for Building an ADU in San Jose
- Silicon Valley rents make ADUs extremely profitable despite high build costs
- Consider a prefab ADU to control costs in a high-cost labor market
- ADU rental income can significantly offset your mortgage in San Jose
- Check with the city's ADU resource center for the latest incentives
Frequently Asked Questions
Can I build an ADU in San Jose?
Yes. ADUs are allowed in All residential zones (R-1, R-2, R-M, R-MH) in San Jose. The maximum size for a detached ADU is 1,200 sq ft. No owner-occupancy is required.
How much does an ADU cost in San Jose?
ADU construction in San Jose typically costs $180,000-$400,000. Garage conversions run $100,000-$220,000, and prefab ADUs cost $130,000-$300,000 (installed).
How much can I rent an ADU for in San Jose?
Average ADU rents in San Jose are $2,000-$2,800/mo for a 1-bedroom and $2,500-$3,500/mo for a 2-bedroom unit.
Do I need parking for an ADU in San Jose?
No parking required. Check with San Jose planning department for the latest California ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in San Jose?
The permit review timeline in San Jose is 60 days. Fees range from $4,000-$14,000.
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