Can You Build an ADU in San Jose?
Yes — San Jose is governed by California's statewide ADU law, which limits what the city can restrict. A 700 sq ft detached ADU here runs about $221,500–$362,500.
Construction in San Jose runs about 15% above the California average, so budget toward the higher end of these ranges.
Detached ADU (700 sq ft)
$221,500–$362,500
Garage conversion (400 sq ft)
$69,000–$126,500
Statewide protection
Yes
What applies in San Jose
California's statewide standard (Cal. Gov. Code §66314 et seq. (former §65852.2)) is the starting point, but parcel-level rules, fees and design review are set locally. Confirm those details with San Jose before design.
Estimate your San Jose ADU cost
Your property
ADU typeEstimated cost in California
$221,500 – $362,500
≈ $316–$518/sq ft turnkey · midpoint $292,000
- $198,500
- Construction
- $52,600
- Design & permits
- $40,900
- Site work
- ✓Size within the guaranteed minimum. Your 700 sq ft ADU is at or under the 800 sq ft your city must allow regardless of other rules.
- ✓4 ft setback. State law caps the side and rear setback at 4 ft, so even a tight lot usually works.
- ✓No extra parking likely required. No parking required if within 1/2 mile of public transit, in a historic district, or part of the existing/proposed primary residence.
- ✓No owner-occupancy requirement. You can rent out both the main home and the ADU — you do not have to live on the property.
- ✓Lot has room. A 700 sq ft ADU uses about 12% of your 6,000 sq ft lot — comfortably within typical coverage limits.
- ✓Ministerial approval in 60 days. By law your city must approve a complete ADU application within 60 days, without discretionary review or a public hearing.
- ✓Impact fees waived. ADUs under 750 sq ft are exempt from impact fees in this state — a saving of several thousand dollars.
Rule basis: Cal. Gov. Code §66314 et seq. (former §65852.2)
If you rent it out
$1,350–$2,175
est. rent/mo
7.3%
gross yield
14.7 yrs
payback
~$19,809/yr after a 7% vacancy allowance, before financing & maintenance.
Financed over 20 yrs at 7.5%, the build is about $2,352/mo — vs ~$1,775/mo in estimated rent.
Estimates are for planning only and are based on regional construction-cost indices and published statewide ADU statutes. Local ordinances, lot conditions and contractor pricing vary — always confirm with your city planning department and a licensed contractor.
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Other California cities
Estimates are for planning only and are based on regional construction-cost indices and published statewide ADU statutes. Local ordinances, lot conditions and contractor pricing vary — always confirm with your city planning department and a licensed contractor.