San Jose says it enacts state ADU law in its zoning code (Municipal Code Chapter 20.80 Part 2.75), and its ADU Universal Checklist reflects state law. ADUs are allowed on single-family, duplex and multifamily lots with a legally built main home.[1]
California cities can set their own ADU rules, but never stricter than state law. Grey lines show the state floor from the HCD ADU Handbook.
| Size limits | No city-specific figure verified. The state minimum below applies; confirm local details with the city. State law: a city's maximum size must allow at least 850 sq ft, or 1,000 sq ft for more than one bedroom, and local rules cannot block an 800 sq ft ADU with 4 ft side and rear setbacks (Gov. Code 66321).[4] |
|---|---|
| Height | No city-specific figure verified. The state minimum below applies; confirm local details with the city. State law: detached ADUs get at least 16 ft; 18 ft within a half mile walk of a major transit stop or high-quality transit corridor (plus 2 ft to match roof pitch) or on a lot with a multistory multifamily building; attached ADUs up to 25 ft or the main home's limit if lower (Gov. Code 66321).[4] |
| Setbacks | No city-specific figure verified. The state minimum below applies; confirm local details with the city. State law: side and rear setbacks can be no more than 4 ft for new ADUs; converted existing space needs no new setback (Gov. Code 66314, 66323).[4] |
| Parking | No city-specific figure verified. The state minimum below applies; confirm local details with the city. State law: at most 1 space per ADU or per bedroom, whichever is less, and none within a half mile walk of public transit, in a historic district, within one block of a car share, or for ADUs inside the house (Gov. Code 66314, 66322).[4] |
| Owner occupancy | A JADU requires owner occupancy of the main home if it shares a bathroom.[3] State law: no owner occupancy requirement for ADUs (Gov. Code 66315). A JADU requires the owner to live on site if it shares a bathroom with the main home (Gov. Code 66333).[4] |
| Permit steps and timeline | Preapproved ADU plans can get a permit the same day as the plan review meeting if the site plan is complete, the lot has a single-family home or duplex, and the lot is outside geohazard, landslide, flood and wildland-urban interface zones. Any active code enforcement case must be resolved first.[2][3] State law: the city must approve or deny a complete application within 60 days when there is an existing home on the lot (Gov. Code 66317).[4] |
| Fees | Building fees follow the city fee schedule. Public Works clearance, parkland and school fees, plus taxes, are paid before the permit is issued.[2] State law: no impact fees on ADUs of 750 sq ft or less; above that, impact fees must be proportional to the size of the main home. Plan check, permit and school fees can still apply.[4] |
Also worth knowing: Tiny homes on wheels are allowed as ADUs on single-family lots with a separate, simpler permit (Bulletin 291).[1]
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Sources
Every fact above links to an official city or state page. Rules change; check the source before you build.
- [1] City of San Jose: ADUs checked Oct 2026
- [2] City of San Jose: Preapproved ADUs checked Oct 2026
- [3] City of San Jose: Bulletin 210 ADU Universal Checklist checked Oct 2026
- [4] HCD ADU Handbook (March 2026) checked Oct 2026