Sonoma County · Building on your lot
Building on your lot in Sonoma County
In unincorporated Sonoma County, the county code sets its own limits on fences, accessory buildings, home businesses, oversized vehicle parking, pools and tree removal. Fence limits depend on the yard and whether the fence is near a street corner.
Key points
- Fence height: Listed zones: use permit for fences over 3 feet in front yards or near corners, over 6 feet in side or rear yards.
- Home businesses: County rule: a home business may use at most 25% of the dwelling, or 500 square feet of a garage or accessory structure.
- Customer visits: County rule: at most 4 customers a day and 2 at a time, weekdays 8 a.m. to 6 p.m.; only residents may be employed.
- Accessory buildings: County rule: on vacant parcels under 2 acres in listed zones, accessory buildings must be under 120 square feet, unless serving existing agriculture.
- Oversized vehicles: County rule: oversized vehicles, boats and trailers may park on county roads at most 6 consecutive hours, then must move at least 72 hours.
- Large trees: County rule: removing redwoods over 48 inches or oaks and other hardwoods over 36 inches in diameter needs a use permit, unless exempt.
Each rule below is marked Sonoma County code or CA state law and links to the section it comes from (checked October 2026). General information, not legal advice.
Sonoma County's code applies in the unincorporated areas of the county. Cities in Sonoma County have their own codes and their own pages.
Fences and walls
Sonoma County code Listed zones: use permit for fences over 3 feet in front yards or near corners, over 6 feet in side or rear yards.
All 4 Sonoma County rules on fences and walls, with the code text →
Sheds, garages and other accessory structures
| Size or lot coverage |
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Running a business from home
Sonoma County code County rule: a home business may use at most 25% of the dwelling, or 500 square feet of a garage or accessory structure. County rule: at most 4 customers a day and 2 at a time, weekdays 8 a.m. to 6 p.m.; only residents may be employed.
All 8 Sonoma County rules on running a business from home, with the code text →
RV and boat parking
Sonoma County code County rule: oversized vehicles, boats and trailers may park on county roads at most 6 consecutive hours, then must move at least 72 hours.
All 3 Sonoma County rules on RV and boat parking, with the code text →
Solar panels and EV chargers
Sonoma County code The building official approves and issues all permits when the application is complete and meets the checklist. No more than 15 feet high, unless a structural engineer shows it meets public safety standards.
All 5 Sonoma County rules on solar panels and EV chargers, with the code text →
Tree removal
Sonoma County code County rule: removing redwoods over 48 inches or oaks and other hardwoods over 36 inches in diameter needs a use permit, unless exempt.
All 13 Sonoma County rules on tree removal, with the code text →
Swimming pools
Sonoma County code The outside surface must have no protrusions or cavities that could serve as handholds or footholds. No more than 2 inches between the ground and the bottom of the enclosure.
All 8 Sonoma County rules on swimming pools, with the code text →
Building in a flood zone
| Floodplain permit |
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|---|---|
| Building in a floodway |
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Grading and erosion control
| Grading without a permit |
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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 |
Affordable units in new housing (inclusionary)
Sonoma County code The rule applies to projects of 1 or more residential units. At least 20 percent of new dwelling units must be affordable; at least half of those go to low-income households.
All 5 Sonoma County rules on affordable units in new housing (inclusionary), with the code text →
Group homes and residential care
| Homes for 7 or more |
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|---|---|
| Homes for 6 or fewer |
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Parking spaces required for homes
Sonoma County code ½ uncovered guest parking space for each dwelling unit, plus an additional ½ parking space for each dwelling unit having more than 2 bedrooms one-half uncovered guest space/dwelling unit
All 10 Sonoma County rules on parking spaces required for homes, with the code text →
Trash and recycling carts
Sonoma County code You must subscribe to weekly solid waste, recyclable materials and organic waste collection services. May be exempt from mandatory service upon approval.
All 4 Sonoma County rules on trash and recycling carts, with the code text →
Other Sonoma County rules on this
Sonoma County's code also has these chapters. We have not summarized their values on this page yet; read them in the library.
- Farm animal limits and backyard hens (§ 26-18-080)
- Park fee for new homes (§ 20-65)
Who this affects
Frequently asked questions
How big can a shed or accessory building be in Sonoma County?
County rule: on vacant parcels under 2 acres in listed zones, accessory buildings must be under 120 square feet, unless serving existing agriculture.
What are the rules for building in a Sonoma County flood zone?
Sonoma County's code: All required building, grading, drainage and similar permits must be obtained before construction or development begins. (In special flood hazard areas. Includes improvements, additions or repairs to existing structures and placing manufactured homes.) (§ 7B-5); No encroachments, including fill and new construction, unless a certified engineering analysis shows no flood level rise. (Applies in the adopted floodway, for flood levels during the base flood.) (§ 7B-12).
What are the grading rules in Sonoma County?
Sonoma County's code: Cuts up to 50 cubic yards and 3 feet deep; small fills; permitted basement, footing, well or septic digs. (Fills: 50 cubic yards or less, watercourse unchanged, 1 foot deep in flood areas, else 3 feet without structures. County grading standards still apply.) (§ 11.04.010).
Can I run a family child care home in Sonoma County?
California law sets this for every city, including Sonoma 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)).
Where are group homes and residential care homes allowed in Sonoma County?
Sonoma County's code: Subject to the same density limits and rules as other residential dwellings of the same type in the same zone. (Applies to facilities serving 7 or more persons.) (§ 26-24-250); Subject to the same density limits and rules as other residential dwellings of the same type in the same zone. (Applies to facilities serving 6 or fewer persons.) (§ 26-24-250).
General information, not legal advice.
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