A San Jose junior ADU must stay within a single-family residence and may have no more than 500 sq ft of interior livable space under state law. City standards allow one with an ADU, and state law requires owner occupancy only when sanitation is shared.
Last verified 2026-10-18. Rules change; the City of San Jose ADU Ally team has the final word (408-793-5302).
Check your lot · free
What the San Jose rules allow on your lot: setbacks, the biggest unit that fits, fees.
Design your ADU · free
Shape it in live 3D: size, rooms, roof and finishes, with an estimate priced for San Jose.
San Jose's Bulletin 210 says an ADU design follows either the City standards in Municipal Code 20.80.175 or the State standards in 20.80.176. The two sets cannot be mixed.
San Jose ADU Universal Checklist (Bulletin 210), Part 3| Type | Est. all-in cost | Est. rent |
|---|---|---|
| Junior ADU (inside the house) | $60,000-$110,000 | $1,575-$1,925/mo |
Estimates for a first conversation, not bids or appraisals. Source: LotUpside price book sj-2026-10.
Ask the City of San Jose ADU Ally team before you rely on these.
Our free check reads your lot against the San Jose rules above from public records: a screening, not a permit or professional advice.
Or design your San Jose ADU in 3D, free.
Measured ADU layouts you can edit and download as CAD files, then check against the San Jose rules above.
We'll match you with a licensed designer and builder in your area and coordinate the project. Free consult, no obligation.
We'll match you with a licensed designer and builder in your area and coordinate the project. Free consult, no obligation.
Licensed partner designers and builders do the design and construction, and the builder holds the construction contract. Partners are signed in some areas so far; elsewhere we'll tell you plainly what we can do.
Government Code 66333(d) counts an attached garage as part of the single-family residence for a junior ADU, which must be within its walls. Government Code 66313(d) caps the junior unit at 500 sq ft of interior livable space; San Jose Municipal Code 20.80.175 B.1 allows one junior ADU with a City-standards ADU.
Only when the junior ADU shares sanitation with the house. Government Code 66333(b) does not require owner occupancy when it has separate sanitation facilities.
Yes. Government Code 66333(e) requires a separate entrance, and section 66333(f) requires an efficiency kitchen with a cooking facility, counter and storage cabinets.
Neither. It is a screening from public records, not professional advice, and not a survey, soils report, appraisal, loan offer or permit; every number is an estimate. A licensed designer confirms the final plan, and your city or county gives final approval.