ADU rules in Castro Valley, CA — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
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.
Alameda County ADU regulations implement California Government Code Section 65852.2 and related state ADU mandates including AB 68, AB 881, SB 13, AB 671, and AB 1033. ADUs are allowed ministerially (no discretionary review, no public hearing) on any lot zoned for single-family or multifamily use. Detached ADUs up to 1,200 square feet and junior ADUs (JADUs) up to 500 square feet within an existing single-family home are allowed. Setbacks are limited to 4 feet side and rear, height up to 16 feet (or up to 18-25 feet in some multifamily cases), and no parking required within a half-mile of transit. AB 1033 (2023) allows ADUs to be sold separately as condominiums where the county opts in. Owner-occupancy requirements are suspended through 2025 for ADUs and applied for JADUs. Permit applications are reviewed by the Alameda County Community Development Agency; ministerial approval must be granted or denied within 60 days of a complete application.
Contact your local code enforcement office for specific penalty information.
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Side-by-side rule comparisons with other cities in Alameda County.
See how other cities in Alameda County handle adu rules.
See how Castro Valley's adu rules rules stack up against other locations.
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