Napa County, CA Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Napa County, CA, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- Permit-Exempt Size
- ≤ 120 sq ft (CBC § 105.2)
- Setbacks (typical)
- 4 ft side/rear
- Side Setback (narrow lots)
- 5 ft on lots under 60 ft wide
- Electrical
- Permit required regardless of shed size
- Code Adoption
- Title 15, Chapter 15.12
Summary
Per the California Building Code section 105.2 (adopted via Napa County Code Title 15, Chapter 15.12), one-story detached storage sheds with a floor area of 120 sq ft or less are exempt from a building permit, but zoning setbacks under Napa County Code Title 18 (including the four-foot side/rear standard for accessory buildings on lots under 60 feet wide) still apply.
Yard & Outdoor Areas: Yards are sanitary, free of garbage, debris, overgrowth, or excessive storage. No dismantled/inoperable vehicles stored on site. Storage sheds, patio covers, and accessory structures are maintained and structurally sound. ... Zoning & Land Use (Check All That Apply): A primary residence exists (or is proposed) on the parcel. ADU complies with required setbacks (4' side/rear + district-specific front setback). Detached ADU is < 1,200 sq ft, or attached ADU is < 50% of primary residence's size.
Full Breakdown
12. 2 exempts from the building-permit requirement one-story detached accessory structures used as tool and storage sheds, playhouses, and similar uses if the floor area does not exceed 120 square feet, the structure has no plumbing or mechanical equipment, and the work is otherwise minor. 140-related provisions, and the County's ADU Delayed Enforcement Inspection Checklist confirms that the four-foot side/rear setback standard applies to most detached accessory structures. Sheds with electrical service still require an electrical permit, and storage of hazardous materials or any habitable conversion triggers full building-permit requirements. Sheds must also be free of pest infestation and structurally sound per the County's Yard & Outdoor Areas standards.
Violations & Fines
Building a shed over 120 sq ft without a permit, or violating zoning setbacks with any shed, can trigger stop-work orders and code-enforcement citations under Napa County Code Title 1 and Title 15. Owners must obtain a retroactive permit or remove the structure. Habitable conversions (sheds used for sleeping) trigger Health & Safety Code violations and ADU-permitting requirements.
Frequently Asked Questions
Do I need a permit for a small garden shed in unincorporated Napa County?
How close to my property line can my shed be?
Can I put electricity in my shed?
Sources & Official References
Other rules in Napa County
How Napa County compares: Shed Permit Requirements by City·California rules heatmap·Compare Napa County to another location·View the California accessory structures overview
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