ADU Rules: Castro Valley vs Fremont
How do adu rules rules compare between Castro Valley, CA and Fremont, CA?
Castro Valley and Fremont have similar restriction levels.
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 →Fremont, CA
Alameda County
Fremont follows CA Gov Code 65852.2: ADUs up to 1,200 sq ft allowed on most residential lots, plus Junior ADUs. Ministerial 60-day review. No owner-occupancy through 2025.
View full Fremont rules →Key Facts Comparison
| Fact | Castro Valley | Fremont |
|---|---|---|
| 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 | - |
| Max Detached Size | - | 1,200 sq ft |
| Setback Minimum | - | 4 ft side and rear |
| Parking | - | Often waived near transit |
| Review Time | - | 60 days ministerial |
| JADU | - | Up to 500 sq ft in primary home |
Highlighted rows indicate differences between cities.
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.
Fremont FAQ
Can I rent my Fremont ADU on Airbnb?
ADUs cannot be rented for terms under 30 days. Fremont prohibits short-term rental of ADUs to preserve housing stock. Long-term rentals of 30 days or more are fully permitted.
Do I need to live on the property if I build an ADU?
No owner-occupancy is required through January 1, 2025, under state law. JADUs always require owner occupancy of either the JADU or the main house. After 2025, Fremont may reimpose owner-occupancy for new ADUs.
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