ADU Rules: Berkeley vs Castro Valley
How do adu rules rules compare between Berkeley, CA and Castro Valley, CA?
Berkeley and Castro Valley have similar restriction levels.
Berkeley, CA
Alameda County
Berkeley regulates ADUs and JADUs under Berkeley Municipal Code Chapter 23.306. One ADU plus one JADU is allowed per single-family lot citywide (Hillside Overlay allows one ADU OR one JADU). New detached ADUs are limited to 16 feet in height, with a 4-foot minimum side and rear setback, and JADUs are capped at 500 sq ft within the existing dwelling.
View full Berkeley rules →Castro Valley, CA
Alameda County
Alameda County complies with California Government Code 65852.2 mandating ministerial ADU approval. ADUs up to 1,200 sqft for detached and JADUs up to 500 sqft are allowed on most residential lots.
View full Castro Valley rules →Key Facts Comparison
| Fact | Berkeley | Castro Valley |
|---|---|---|
| Code Section | BMC 23.306 (Development Standards 23.306.030) | - |
| Units Allowed | 1 ADU + 1 JADU per single-family lot | - |
| Side/Rear Setback | 4 ft (new construction) | - |
| JADU Max Size | 500 sq ft (within dwelling) | - |
| STR Use | Prohibited by deed restriction | - |
| State law | - | Gov Code 65852.2 |
| Detached ADU max | - | 1,200 sqft |
| JADU max | - | 500 sqft |
| Side/rear setback | - | 4 feet |
| Review time | - | 60 days ministerial |
Highlighted rows indicate differences between cities.
Berkeley FAQ
How many ADUs can I build in Berkeley?
Under BMC 23.306, a single-family lot may have one ADU plus one JADU. In the Hillside Overlay, the limit is one ADU or one JADU (not both).
Do I need a public hearing for a Berkeley ADU?
No. State law requires ministerial review without a public hearing based on objective criteria, and BMC 23.306 implements that standard for Berkeley.
Can I rent my Berkeley ADU as a short-term rental?
No. A recorded deed restriction required by BMC 23.306 prohibits short-term rental use (under 14 days) of any ADU or JADU.
Castro Valley FAQ
Do I need a public hearing?
No, ADUs are approved ministerially by county staff under state law; no planning commission or neighbor notice is required if the application meets objective standards.
Can I sell my ADU separately?
AB 1033 (2023) allows separate sale as condominium only if Alameda County opts in by local ordinance; check current county policy.
Compare other topics
See how Berkeley and Castro Valley compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool