ADU Rules: Mountain View vs San Jose
How do adu rules rules compare between Mountain View, CA and San Jose, CA?
Mountain View and San Jose have similar restriction levels.
Mountain View, CA
Santa Clara County
Mountain View ADU regulations follow California Government Code 65852.2 as amended by AB 68, AB 881, SB 13, and AB 1033. Ministerial approval applies to most ADUs and JADUs on single-family lots.
View full Mountain View rules →San Jose, CA
Santa Clara County
San Jose regulates ADUs and JADUs under San Jose Municipal Code §20.30.150, originally updated by the City Council in mid-2018 and amended to track state law. Detached ADUs are capped at 1,200 sq ft (on lots of 9,000 sq ft or larger; 1,000 sq ft cap on smaller lots), and JADUs at 500 sq ft within the primary single-family dwelling.
View full San Jose rules →Key Facts Comparison
| Fact | Mountain View | San Jose |
|---|---|---|
| ADU per lot | One ADU plus JADU | - |
| Min max size | At least 1,200 sq ft | - |
| Setback | 4 ft side and rear | - |
| Height transit | Up to 18 feet | - |
| Review time | 60 days ministerial | - |
| Code Section | - | SJMC 20.30.150 |
| Max Detached (lot 9,000+) | - | 1,200 sq ft |
| Max Detached (smaller lot) | - | 1,000 sq ft |
| Max JADU | - | 500 sq ft |
| Height (1-story / 2-story) | - | 18 ft / 24 ft |
Highlighted rows indicate differences between cities.
Mountain View FAQ
Do I need to live on site to build an ADU?
No. State law currently prohibits Mountain View from imposing owner-occupancy on standard ADUs, though a JADU generally requires owner occupancy of either unit.
Can I short-term rent my ADU?
ADUs in Mountain View may not be used as short-term vacation rentals under 30 days; long-term rental is the standard allowed use.
San Jose FAQ
How big can my San Jose ADU be?
Detached ADUs on lots of 9,000 sq ft or larger may be up to 1,200 sq ft; on smaller lots, the cap is 1,000 sq ft. JADUs are limited to 500 sq ft within the primary dwelling, per SJMC 20.30.150.
How tall can a San Jose ADU be?
One-story detached ADUs are limited to 18 feet, and two-story detached ADUs to 24 feet, under SJMC 20.30.150.
Can I rent my San Jose ADU on Airbnb?
No. ADUs must be rented for terms of 30 days or longer. Short-term rental of an ADU is not permitted under San Jose's ADU and STR rules.
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