Napa County · Building on your lot
Building on your lot in Napa County
Napa County's code applies only in unincorporated areas of the county. It sets fence heights, rear-yard accessory-building limits and home-business rules, including limits on wine-related uses.
Key points
- Fence height: County rule: fences are limited to 4 ft in front yard setbacks and 8 ft in side and rear setbacks, see-through above 6 ft.
- Accessory buildings: County rule: rear-yard garages and accessory buildings are limited to 15 ft at the ridgeline and 50% of the rear yard.
- Home businesses: County rule: a home business may use 25% of the home's floor area, is run by residents only, and needs an administrative permit.
Each rule below is marked Napa County code or CA state law and links to the section it comes from (checked October 2026). General information, not legal advice.
Napa County's code applies in the unincorporated areas of the county. Cities in Napa County have their own codes and their own pages.
Fences and walls
Napa County code County rule: fences are limited to 4 ft in front yard setbacks and 8 ft in side and rear setbacks, see-through above 6 ft.
All 5 Napa County rules on fences and walls, with the code text →
Sheds, garages and other accessory structures
Napa County code County rule: rear-yard garages and accessory buildings are limited to 15 ft at the ridgeline and 50% of the rear yard.
All 5 Napa County rules on sheds, garages and other accessory structures, with the code text →
Running a business from home
Napa County code County rule: a home business may use 25% of the home's floor area, is run by residents only, and needs an administrative permit.
All 4 Napa County rules on running a business from home, with the code text →
Lot splits under SB 9
| Owner occupancy |
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|---|
Solar panels and EV chargers
Napa County code Apply in person, by mail or electronically; a complete, checklist-compliant application is approved administratively with all required permits. Complete applications meeting the checklist and standard plan get a building or other nondiscretionary permit as soon as reasonably practicable.
All 3 Napa County rules on solar panels and EV chargers, with the code text →
Building in a flood zone
| Floodplain permit |
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|---|---|
| Building in a floodway |
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Noise and construction hours
Napa County code 7 a.m. to 7 p.m. 10 p.m. to 7 a.m.
All 16 Napa 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 |
Group homes and residential care
| Parking |
|
|---|
Parking spaces required for homes
Napa County code 0.25 guest parking spaces per unit 1 space per studio unit
All 4 Napa County rules on parking spaces required for homes, with the code text →
Historic homes
Napa County code More than 50 years old Commission review
All 4 Napa County rules on historic homes, with the code text →
Other Napa County rules on this
Napa County's code also has these chapters. We have not summarized their values on this page yet; read them in the library.
- Keeping bees (apiaries) (§ 6.12.020)
- Limits on keeping roosters (§ 6.18.030)
- Truck and RV parking on residential streets (§ 10.08.080) — on public streets in residential areas
- Erosion control in erosion hazard areas (§ 18.108.070) — erosion hazard areas only
Who this affects
Frequently asked questions
Can I split my lot under SB 9 in Napa County?
Napa County's code: The applicant signs an affidavit to live in 1 new unit as their main home for at least 3 years. (Does not apply to a community land trust or qualified nonprofit corporation.) (§ 17.17.030).
What are the rules for building in a Napa County flood zone?
Napa County's code: A floodplain permit is needed before filling, removing material, digging, building, altering structures or changing embankments. (In a special flood hazard area.) (§ 16.04.560); No permit for floodway work unless fully inside an existing footprint or certified not to raise base flood elevation. (In a defined floodway.) (§ 16.04.560).
Can I run a family child care home in Napa County?
California law sets this for every city, including Napa 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 Napa County?
Napa County's code: One off-street parking space for each 2 visitors. (Applies to medium or large residential care facilities; based on the most visitors at one time.) (§ 18.104.170); One more off-street parking space for each full-time or part-time employee. (Applies to medium or large residential care facilities; based on the most employees on duty at one time.) (§ 18.104.170).
General information, not legal advice.
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