ADU Rules in Santa Clara County, California
We track 3 cities in Santa Clara County. Each city writes its own ADU ordinance on top of California law, so size limits, fees, and design rules differ from one city to the next. Among the cities we track, San Jose has the lowest starting permit fees ($5,000 – $20,000).
Cities
3
Max Detached Size
1,200 sq ft
Build Costs From
$200,000
Pre-approved Plans
1 of 3 cities
Santa Clara County Cities Compared
| City | Max detached | Height | Permit fees | Build cost |
|---|---|---|---|---|
| San Jose | 1,200 sq ft | 18 ft (one-story detached) | $5,000 – $20,000 | $200,000 – $550,000 |
| Sunnyvale | 1,200 sq ft | 16 ft (detached) | $11,000 – $22,000 | $220,000 – $430,000 |
| Santa Clara | 1,200 sq ft | 18 ft (one-story detached) | $11,000 – $22,000 | $220,000 – $430,000 |
San Jose ADU rules
San Jose allows two-story detached ADUs up to 24 ft on single-family lots, taller than the state floor, and a zoning update proposes raising that to 25 ft. The city's Preapproved ADU program, with plans from several vendors and a dedicated review team, is its fastest and lowest-cost permit path. ADUs are allowed on single-family, duplex and multifamily properties.
Sunnyvale ADU rules
Sunnyvale guarantees an 850 sq ft one-bedroom or 1,000 sq ft two-bedroom ADU on any residential parcel regardless of the zone's other standards, and streamlined ADUs need no discretionary planning permit. Typical lots of 6,000 to 8,000 sq ft fit a detached unit behind 4 ft side and rear setbacks. Check whether your address is served by Silicon Valley Power or PG&E before planning electrical work.
Santa Clara ADU rules
Santa Clara caps detached ADUs at 1,000 sq ft on lots of 5,500 sq ft or less and 1,200 sq ft on larger lots, with heights of 18 ft for one story or 25 ft for 1.5 stories. Its Pre-Approved ADU Plans Program lists builder plans the city has already approved, but it excludes flood zone and historic properties. Fees are high, but so are Silicon Valley rents.
Rules that apply in every California city are summarized in our California ADU law guide. See all California cities or compare every city side by side.