Local zoning · Napa County

Napa County — Nonconforming Uses

Nonconforming Uses under the Napa County local zoning and planning code, with the controlling citations.

Last reviewed: July 6, 2026

Overview

This page explains how Napa County treats existing uses, structures, and lots that no longer meet today’s zoning rules in the unincorporated areas. The governing rules live in Title 18 (Zoning), specifically the County’s Chapter 18.132 — Legal Nonconformities. These standards control whether a nonconforming situation can continue, when it is considered abandoned, and what limited changes are allowed while you pursue new work such as remodels or site moves (§ 18.132.010–18.132.050) .

Plain-English anchor: A “legal nonconformity” in unincorporated Napa County is a use, structure, or lot that was legal when established but doesn’t meet today’s zoning; it can continue, but you generally can’t enlarge or intensify it, and you can lose its status if it’s abandoned (§ 18.132.010, § 18.132.040) .

What counts as a legal nonconformity

The County recognizes three categories: nonconforming uses, structures, and lots that were lawful when created but later became nonconforming due to code changes (§ 18.132.010) .
Signs follow separate nonconforming rules in the County’s signage chapter; see Chapter 18.116 and our related page on Napa County Signage (§ 18.132.010) .

Continuance and limits on change

A legal nonconformity may be repaired, maintained, restored, rebuilt after destruction (regardless of extent), rehabilitated, remodeled, or rearranged — but not enlarged or intensified, not relocated from its original location, and not increased in business volume, hours, traffic, waste, or resource consumption (§ 18.132.030(A)) .
Narrow exceptions the Director may allow: (i) up to 500 sq ft of accessory storage added after November 1, 2008, but only for certain legal nonconforming restaurant sites defined in the code; (ii) changes solely to meet ADA access needs; and (iii) minor relocations that reduce the degree of nonconformity (for example, moving farther from a required setback) (§ 18.132.030(A)) .
Before permits are issued for work on a legal nonconformity, the County requires a Certificate of Present Extent documenting what existed and remains lawful (§ 18.132.030(C); § 18.132.050) .

Loss of nonconforming status (abandonment and nuisance)

A legal nonconformity loses protection if: (1) it’s found to be a public nuisance and not abated as required; or (2) it’s voluntarily abandoned — defined as cessation for six consecutive months or twelve nonconsecutive months in any two-year period (longer than one season for seasonal uses) (§ 18.132.040(A)–(B)) .
Act-of-God exception: if essential facilities were destroyed by events like fire, earthquake, or similar, nonconformity is not deemed abandoned if the use recommences within specified timelines (generally within two years, with earlier building-permit timing requirements), but this exception does not apply to flood damage inside a mapped floodway (§ 18.132.040(B)) .

Nonconforming lots

In any district where a single-family dwelling is permitted, a dwelling and accessory buildings may be constructed on any legally created, now-substandard lot, provided all other applicable standards of the code and state/federal laws are met (§ 18.132.020) . Check Napa County Development Standards for setbacks, height, and similar controls that still apply.

Certificate of Present Extent — process

Owners may apply at any time, or must apply when requested by the Director if there’s a dispute about abandonment, permit entitlement, or the scope/intensity of the nonconformity (§ 18.132.050(A)) .
The Zoning Administrator holds a noticed public hearing (some residential cases can be decided administratively) and issues the certificate; appeals go to the Board of Supervisors (§ 18.132.050(C)–(E)) .
The certificate is filed with the County Assessor (§ 18.132.050(F)) .

Interactions you should know

Front-yard averaging: when the County averages front setbacks along a block face, it treats certified nonconforming front yards as lawful for the averaging calculation (§ 18.104.260(D)) .
Legacy wineries in agricultural districts: pre‑1974 wineries that lawfully existed without use permits are recognized, but expansion beyond what existed then needs a new or amended use permit. The extent of such uses is determined through the nonconformity certificate process (§ 18.16.020(G); § 18.20.020(H); § 18.132.050) . Also see special winery standards in § 18.104.220–§ 18.104.230 and legacy permit rules in § 18.104.255 .
ADUs on nonconforming properties: Napa County’s ADU section states the County “may not require as a condition of approval the correction of nonconforming zoning conditions” for ADUs; see § 18.104.180(B)(1)(c). That can materially affect improvement strategy on nonconforming residential lots in the unincorporated area (also see California ADU law) (§ 18.104.180) .
Variances do not legalize a prohibited use: a variance cannot authorize a use not otherwise allowed in the district (§ 18.128.080); see Napa County Variances and Exceptions for relief routes on dimensional standards (§ 18.128.080) .

District-by-District context for nonconformities

Below are unincorporated Napa County base districts you are most likely to encounter when evaluating nonconformities. “Key dimensional standards” live in the County’s Schedule of Zoning District Regulations — verify the numbers in § 18.104.010 and related sections in Napa County Development Standards (exceptions and overlays may apply) .

AP — Agricultural Preserve

Purpose: Protect and prioritize agriculture in fertile valley and foothill areas; exclude urban-type uses (§ 18.16.010) .
Typical permitted uses: agriculture; one single-family dwelling per legal lot; certain ADUs/JADUs under § 18.104.180; legacy pre‑1974 wineries allowed to continue if not abandoned and extent certified (§ 18.16.020(F), (G)) .
Key dimensional standards: See § 18.104.010 (verify setbacks, lot area, height). Note special side-yard rules on small ag/residential lots and farmworker center minimum sizes (§ 18.104.010(B), (D)) .
Where it applies: valley floor/foothill agricultural lands (§ 18.16.010) .
Nonconforming-use implication: Many older wineries rely on § 18.132.050 certificates to document extent; expansions require a use permit (§ 18.16.020(G)) .

AW — Agricultural Watershed

Purpose: Protect agriculture and sensitive watershed/foothill areas; avoid erosion and resource impacts (§ 18.20.010) .
Typical permitted uses: agriculture; one single-family dwelling; ADUs/JADUs under § 18.104.180; legacy pre‑1974 wineries, small-winery exemptions, and permitted wineries per prior use permits, with no expansion absent new permits (§ 18.20.020(H)–(J)) .
Key dimensional standards: See § 18.104.010 (verify), plus same small-lot side-yard and farmworker center exceptions as AP (§ 18.104.010(B), (D)) .
Where it applies: hillsides, watershed areas, reservoirs and tributaries (§ 18.20.010) .
Nonconforming-use implication: Certificates are essential to fix the scope of legacy wineries; expansions trigger current winery standards and permits (§ 18.132.050; § 18.104.220–.230) .

RS — Residential Single

Purpose: Single-family neighborhoods.
Typical permitted uses: SFD by right; other community/residential uses via use permit (e.g., child day care centers, private schools) (§ 18.52.030) .
Key dimensional standards: See § 18.104.010 (verify). Front-yard averaging may treat certified nonconforming front yards as lawful inputs (§ 18.104.260(D)) .
Where it applies: residential areas outside city limits.
Nonconforming-use implication: Nonconforming homes/lots often rely on § 18.132.020 for SFD construction on substandard legal lots and § 18.132.050 for certificates .

RM — Residential Multiple

Purpose: Multifamily areas with a range of residential types.
Typical permitted uses: multifamily dwellings, SROs, small/medium residential care; ADUs/JADUs subject to § 18.104.180 (§ 18.60.020) .
Key dimensional standards: See § 18.104.010 (verify).
Where it applies: multifamily-designated neighborhoods in the unincorporated area.
Nonconforming-use implication: Certificates document lawful unit counts/yard encroachments; some residential questions may be administratively decided (§ 18.132.050(C)) .

CN — Commercial Neighborhood

Purpose: Neighborhood-serving retail and services.
Typical permitted uses: a range of small retail and service uses by use permit; agriculture allowed; telecom per standards (§ 18.32.020–.030) .
Key dimensional standards: See § 18.104.010 (verify).
Where it applies: local commercial nodes (e.g., Lake Berryessa/Capell Valley options listed in code).
Nonconforming-use implication: Existing nonconforming commercial buildings can, in specific cases, host certain uses by permit (e.g., child day care center) (§ 18.104.040; cross-referenced in various sections) .

MC — Marine Commercial

Purpose: Waterfront/marine-oriented commercial.
Typical permitted uses and standards: see MC chapter; includes parking and signage standards referenced to Chapter 18.116 (§ 18.34.080–.100) .
Key dimensional standards: See § 18.104.010 (verify) (§ 18.34.100) .
Where it applies: marine interface areas.
Nonconforming-use implication: Existing yards/structures may be maintained within § 18.132.030 limits; new work must meet MC performance standards (e.g., parking location, lighting) (§ 18.34.080) .

I — Industrial

Purpose: Areas exclusively for a range of industrial/manufacturing uses (§ 18.36.010) .
Typical permitted uses: agriculture; industrial uses by permit; telecom per standards; exterior storage in screened side/rear yards (§ 18.36.020–.040) .
Key dimensional standards: See § 18.104.010 (verify).
Where it applies: designated industrial areas (e.g., Airport Industrial Area).
Nonconforming-use implication: Certificates help confirm nonconforming floor area or yard encroachments; expansion generally requires bringing elements into conformance or securing new permits (§ 18.132.050) .

IP — Industrial Park

Purpose: Light industrial/office park settings.
Typical permitted uses: offices; R&D; light manufacturing by use permit; telecom per standards (§ 18.40.020) .
Key dimensional standards: See § 18.104.010 (verify).
Where it applies: planned industrial park areas.
Nonconforming-use implication: Treat as in I district; confirm nonconforming site coverage/parking before tenant improvements. Check Napa County Parking for current parking standards cross-applied by permit conditions (§ 18.124.060(B)) .

AV — Airport

Purpose: Sites for airport operations and aviation-related uses; protect safety and minimize conflicts (§ 18.24.010) .
Typical permitted uses: specified airport facilities by right; additional aviation-related and commercial/service uses by use permit (§ 18.24.020–.030) .
Key dimensional standards: See § 18.104.010 (verify).
Where it applies: County Airport and Parrett Field (Angwin) areas.
Nonconforming-use implication: Nonconforming uses must also respect Airport Land Use Compatibility requirements where applicable; expansions often need use permits.

PL — Public Lands

Purpose: Public facilities, parks, and related civic uses.
Typical standards: parking, signage, drainage/watercourse protection, and design standards are codified for PL projects (§ 18.50.070–.120, as applicable) .
Key dimensional standards: See § 18.104.010 (verify).
Where it applies: parcels in the PL district across unincorporated areas.
Nonconforming-use implication: Work on legacy public facilities still triggers conformance with current PL performance standards unless limited by § 18.132.030.

PD — Planned Development

Purpose: Custom, master-planned development subject to an approved development plan and agreement (§ 18.48.130–.150) .
Typical permitted uses: as set by the PD plan; earlier PC/PD plans remain valid but amendments must follow current procedures (§ 18.48.150) .
Key dimensional standards: set by the PD plan; confirm against § 18.104.010 where referenced.
Where it applies: specific PD-zoned tracts in unincorporated areas.
Nonconforming-use implication: Older PD approvals may deem uses “conforming”; later changes proceed through plan amendments rather than the generic nonconforming pathway (§ 18.48.150(A)) .

Nonconformities — rules at a glance

Topic	What the County allows or requires	Code Reference
Definition	Lots, structures, and uses that were legal when established but conflict with current zoning may continue, subject to Chapter 18.132. Signs follow Chapter 18.116.	§ 18.132.010
Work allowed	Repair, maintenance, restoration, rebuilding after destruction (regardless of extent), rehabilitation, remodeling, or rearrangement — but no enlargement or intensification; no relocation unless it reduces the nonconformity.	§ 18.132.030(A)
Narrow exceptions	Director may approve: up to 500 sq ft of accessory storage for certain legacy restaurant parcels; ADA-driven changes; minor relocations that decrease the nonconformity.	§ 18.132.030(A)
Certificate required	Obtain a Certificate of Present Extent before applying for building/other permits tied to the nonconformity.	§ 18.132.030(C), § 18.132.050
Abandonment	Loss of status if ceased 6 consecutive or 12 nonconsecutive months in 2 years (seasonal: more than one season), unless Act-of-God exception timelines are met; floodway events excluded from the exception.	§ 18.132.040(B)
Nonconforming lots	SFD and accessory buildings may be built on any legally created substandard lot in districts that allow SFDs, if all other laws/standards are met.	§ 18.132.020
Front-yard averaging	Certified nonconforming front yards count as lawful in front-yard averaging.	§ 18.104.260(D)
ADUs on nonconforming sites	County may not condition ADU approval on correcting nonconforming zoning conditions.	§ 18.104.180(B)(1)(c)
No use variances	Variances cannot authorize a use not otherwise permitted.	§ 18.128.080

Checklist

Confirm the parcel is in the unincorporated area and identify its base district and any overlays via Napa County Zoning and Napa County Overlay Districts.
Assemble evidence showing the original legality and scope: approvals, plans, dated photos, assessor records — you’ll need this for the Certificate of Present Extent (§ 18.132.050) .
Verify the use/structure was not abandoned (watch the 6/12‑month clock and the seasonal-use rule; consider Act‑of‑God timelines) (§ 18.132.040) .
Test your proposal against the “no enlargement/intensification/relocation” rule; if changes are only ADA-related or qualify as a Director-authorized minor reduction of nonconformity, document that (§ 18.132.030(A)) .
For winery or ag uses, confirm whether legacy status applies and whether a new or amended use permit is needed before any expansion (§ 18.16.020(G); § 18.20.020(H)) .
If adding an ADU, note the County cannot require correction of nonconforming zoning conditions solely to approve the ADU (§ 18.104.180(B)(1)(c)); still meet all other applicable standards and Napa County Design Review triggers if any .
Cross-check current Napa County Development Standards (setbacks, height, coverage) and any Napa County Parking or Napa County Landscaping and Screening requirements that may apply through conditions or site work (§ 18.124.060) .
If strict standards create hardship, explore relief via Napa County Variances and Exceptions; remember, no variance can authorize a prohibited use (§ 18.128.080) .

Risks & Ambiguities

Issue	Why it matters	What to verify
Abandonment timing	Gaps in operation can terminate protections	Operating records vs. the 6/12‑month rule; seasonal-use documentation (§ 18.132.040)
“Enlargement” vs. maintenance	Scope creep during remodels can cross the line	Net change in floor area/cubic content and intensity; confine work to § 18.132.030(A)
Minor relocations	Moving a structure could increase nonconformity	Show the move reduces the nonconformity (e.g., greater setback) (§ 18.132.030(A))
Restaurant storage exception	It’s very narrow (time/place/use-limited)	Confirm parcel history (pre‑7/1/1993) and use (primarily restaurant) for the 500 sq ft storage allowance (§ 18.132.030(A))
Act-of-God rebuilds	Deadlines and floodway carve-out apply	Start permits within required windows; floodway events are excluded from the exception (§ 18.132.040(B))
Legacy winery scope	Extent controls operations and expansions	Certificate of extent; applicable winery standards and any prior permits (§ 18.16.020(G); § 18.20.020(H); § 18.132.050)
Front-yard averaging	Can legitimize a smaller front yard	Need a certificate to count a nonconforming front yard in averaging (§ 18.104.260(D))
Use variances	Can’t legalize a prohibited use	Consider rezoning or use permit instead; variance won’t change use permissions (§ 18.128.080)

Plain-English Summary

If your property in unincorporated Napa County has something “grandfathered,” you can generally keep using it and fix it up — but you can’t make it bigger or busier, and you’ll likely need a County certificate that locks in what’s legal today. Stop the nonconforming use too long and you lose your rights; expand or relocate it and you’ll need to meet current rules or seek new approvals. ADUs are a notable exception: the County cannot make you fix unrelated old zoning issues just to get an ADU approved.

Source References

Napa County Zoning Code — Legal Nonconformities: § 18.132.010–§ 18.132.050
Additional Zoning District Regulations (front-yard averaging; winery standards): § 18.104.010, § 18.104.220–§ 18.104.230, § 18.104.255, § 18.104.260(D)
Agricultural districts and legacy winery recognition: § 18.16.010–.020, § 18.20.010–.020, § 18.20.040
Residential districts: § 18.52.030 (RS); § 18.60.020–.030 (RM)
Commercial/industrial districts: § 18.32.020–.030 (CN); § 18.34.080–.100 (MC); § 18.36.010–.040 (I); § 18.40.020 (IP)
Airport/Public Lands/Planned Development: § 18.24.010–.030 (AV); § 18.50.070–.120 (PL); § 18.48.130–.150 (PD)
ADU provisions (nonconforming conditions not required to be corrected): § 18.104.180(B)(1)(c)
Variances — no authorization of prohibited uses: § 18.128.080
For broader context, see: Napa County zoning & planning overview, Napa County Land Use, and Napa County Design Review

Sources

Retrieved passages

Napa County Zoning Code (Chapter 18.132) High relevance
Napa County Zoning Code (Section 370) High relevance
Napa County Zoning Code (Title 16) High relevance
Napa County Zoning Code (Section 18.132.040.) High relevance
Napa County Zoning Code (§ 7) Medium relevance
Napa County Zoning Code (§ 21) Medium relevance
Napa County Zoning Code (§ 66314) Medium relevance
Napa County Zoning Code (section other) Medium relevance
Napa County Zoning Code (§ 66333) Medium relevance
CBC § 66314 (§ 66314) Medium relevance
Napa County Zoning Code (§ 4) Medium relevance
CBC § 202 (section 202) Medium relevance
Napa County Zoning Code (§ 5) Medium relevance
Napa County Zoning Code (§ 2) Medium relevance
Napa County Zoning Code (§ 3) Medium relevance
Napa County Zoning Code (Section 18.104.010) Medium relevance

Cited sections

Official Napa County code library

Frequently asked questions

Can I rebuild a nonconforming structure after a fire in unincorporated Napa County?

Generally yes. Napa County allows legal nonconformities to be “restored” or “rebuilt following destruction regardless of the extent,” so long as the project does not enlarge or intensify the nonconformity and otherwise meets the chapter’s limits (§ 18.132.030(A)) . Confirm timelines if the use ceased during repairs to avoid “abandonment” (§ 18.132.040) .

How long can a nonconforming use sit idle before rights are lost?

Cessation for six consecutive months or twelve nonconsecutive months in any two-year period (or more than one season for seasonal uses) is “voluntary abandonment,” which ends protection (§ 18.132.040(B)) . There’s an Act-of-God exception with strict deadlines, but it does not apply to floods inside a mapped floodway (§ 18.132.040(B)) .

Do I need a County certificate before I pull permits on a nonconforming building?

Yes. Before applying for building or other permits tied to a legal nonconformity, you must obtain a Certificate of Present Extent documenting its lawful scope (§ 18.132.030(C), § 18.132.050) .

Can I expand a legal nonconforming winery in the AP or AW districts?

Not without approvals. Pre‑1974 wineries may continue at their certified extent, but any expansion generally requires a new or amended use permit, and must meet current winery regulations (§ 18.16.020(G); § 18.20.020(H); § 18.132.050) .

My lot is smaller than current minimums. Can I still build a house?

Often yes. If a single-family dwelling is allowed in the district, you can build an SFD and accessory buildings on a legally created, now‑substandard lot if all other standards and laws are met (§ 18.132.020) . Verify setbacks and height in § 18.104.010 and any overlays.

Will the County make me fix old zoning issues to get an ADU approved?

No. Napa County’s ADU rules state the County may not require correction of nonconforming zoning conditions as a condition of ADU approval (§ 18.104.180(B)(1)(c)) . You must still satisfy applicable ADU standards and health/safety requirements.

Can I “slide” a nonconforming building to a different spot on the lot?

Only if the move reduces the nonconformity. Minor relocations are allowed when they decrease the degree of nonconformity (e.g., moving farther from a setback line), subject to Director determination (§ 18.132.030(A)) .

How are front setbacks measured on blocks with older, shallow-front homes?

Napa County uses front-yard averaging in some cases and treats certified nonconforming front yards as lawful when computing the average (§ 18.104.260(D)) . That can keep your required front yard from jumping to today’s full standard.

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