Alameda County · Building on your lot
Building on your lot in Alameda County
Alameda County's code applies only in unincorporated areas of the county. It sets fence heights by yard and corner location, limits detached accessory buildings in R districts, and lists businesses not allowed as home occupations.
Key points
- Fence height: County fence limits: 4 feet in required front yards, 2 feet near corner-lot intersections, 6 feet elsewhere in A or R districts.
- Accessory buildings: In R districts, the county limits detached accessory buildings to one story and 15 feet, at least 6 feet from other buildings.
- Home business: County home occupations may use at most 1/4 of the dwelling unit; barber shops, beauty shops, real estate offices and massage are not allowed.
Each rule below is marked Alameda County code or CA state law and links to the section it comes from (checked October 2026). General information, not legal advice.
Alameda County's code applies in the unincorporated areas of the county. Cities in Alameda County have their own codes and their own pages.
Fences and walls
Alameda County code County fence limits: 4 feet in required front yards, 2 feet near corner-lot intersections, 6 feet elsewhere in A or R districts.
All 5 Alameda County rules on fences and walls, with the code text →
Sheds, garages and other accessory structures
Alameda County code In R districts, the county limits detached accessory buildings to one story and 15 feet, at least 6 feet from other buildings.
All 4 Alameda County rules on sheds, garages and other accessory structures, with the code text →
Running a business from home
Alameda County code County home occupations may use at most 1/4 of the dwelling unit; barber shops, beauty shops, real estate offices and massage are not allowed.
All 12 Alameda County rules on running a business from home, with the code text →
Grading and erosion control
Alameda County code A grading permit is needed for excavation of 150 cubic yards or more. Fill less than 2 feet deep on natural ground sloped less than 5:1 (20% slope) needs no permit.
All 5 Alameda County rules on grading and erosion control, with the code text →
Building on a hillside
| When hillside rules apply |
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Park and impact fees for new homes
Alameda County code 5 acres of park land per 1,000 people. $11,550.00 total per unit, including a $2,175.00 development increment.
All 6 Alameda County rules on park and impact fees for new homes, with the code text →
Noise and construction hours
Alameda County code On weekdays, no use from 7 p.m. to 7 a.m. if plainly heard 50 feet away. On weekends, no use from 7 p.m. to 8 a.m. if plainly heard 50 feet away.
All 12 Alameda County rules on noise and construction hours, with the code text →
Family child care homes
| Zoning | A small or large family child care home is a residential use and a use by right under all local ordinances, including zoning |
|---|---|
| Business license or fee | A city or county may not charge a business license, fee or tax to run a family child care home |
| Local rules | Local limits on height, setbacks, lot size, health and safety must be the same as for every other home in the same zone |
| Small home | Up to eight children, counting the provider's own children under 10 who live there |
| Large home | 7 to 14 children, counting the provider's own children under 10 who live there |
Home alarm permits and false alarms
Alameda County code A sheriff's office alarm permit is required before using an alarm. The fee is set by board resolution. Initial and renewal permit fees are waived.
All 4 Alameda County rules on home alarm permits and false alarms, with the code text →
Historic homes
Alameda County code A building at least 50 years old is screened before a demolition or relocation permit. The permit application goes to the planning director for a preliminary decision on eligibility for the register.
All 5 Alameda County rules on historic homes, with the code text →
Other Alameda County rules on this
Alameda County's code also has these chapters. We have not summarized their values on this page yet; read them in the library.
- Animal fanciers permit for extra dogs, cats or livestock (Ch. 5.12) — residential zones only
- Floodplain management (Ch. 15.40)
Who this affects
Frequently asked questions
What extra rules apply to a hillside lot in Alameda County?
Alameda County's code: Lots averaging over 20% slope: required parking may be as close as 5 feet to the street property line. (Hillside overlay (H-O) districts in the Castro Valley General Plan; subject to site development review.) (§ 17.51.010); Where the whole lot has natural grade over 30%, development needs site development review. (Hillside overlay (H-O) districts in the Castro Valley General Plan.) (§ 17.51.010).
Can I run a family child care home in Alameda County?
California law sets this for every city, including Alameda County: Zoning: A small or large family child care home is a residential use and a use by right under all local ordinances, including zoning (Health & Safety Code § 1597.45(a)); Business license or fee: A city or county may not charge a business license, fee or tax to run a family child care home (Health & Safety Code § 1597.45(b)); Local rules: Local limits on height, setbacks, lot size, health and safety must be the same as for every other home in the same zone (Health & Safety Code § 1597.45(e)); Small home: Up to eight children, counting the provider's own children under 10 who live there (Health & Safety Code § 1596.78(c)); Large home: 7 to 14 children, counting the provider's own children under 10 who live there (Health & Safety Code § 1596.78(b)).
General information, not legal advice.
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