Alameda County, CA Building Setbacks & Zoning: Structure Height Limits (2026)
Key Facts
- Base height cap
- 25 ft / 2 stories
- Bonus formula
- +2 ft per 10 ft extra width
- Max height with bonus
- 30 ft
- Bonus requires
- 100-ft depth, 70-ft width lot
- Applies to
- unincorporated R-1 districts only
Summary
Unincorporated Alameda County caps R-1 single-family homes at two stories and 25 feet, though wide, deep lots can earn extra height up to a 30-foot ceiling.
No dwelling shall have a height of more than two stories... nor shall any building or structure have a height in excess of twenty-five (25) feet, except as provided...by Section 17.52.090. Provided the parcel has a median lot depth of at least one hundred (100) feet, a median lot width of at least seventy (70) feet...the height of a dwelling may be increased by two feet for each full ten feet than the median lot width exceeds seventy (70) feet up to a maximum height of thirty (30) feet.
Full Breakdown
In R-1 districts across unincorporated Alameda County, including Castro Valley, San Lorenzo and Ashland, a dwelling cannot exceed two stories or 25 feet. A lot with at least 100 feet of median depth, 70 feet of median width, and 50 feet of frontage can add two feet of height for every full ten feet its width exceeds 70 feet, up to a 30-foot cap. The rule governs only unincorporated territory; Oakland, Berkeley and the county's other twelve incorporated cities set their own residential height limits.
Violations & Fines
Exceeding the height cap without qualifying for the lot-width bonus can stall a building permit or force redesign at the plan-check stage before construction proceeds.
Frequently Asked Questions
Can an R-1 home in Castro Valley be taller than 25 feet?
Does the county height cap apply in the City of Alameda?
Sources & Official References
Other rules in Alameda County
California rules heatmap·Compare Alameda County to another location·View the California building setbacks & zoning overview
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