Local zoning · Napa County

Napa County — Overlay Districts

Overlay Districts under the Napa County local zoning and planning code, with the controlling citations.

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Last reviewed: July 6, 2026

Overview

In unincorporated areas of Napa County, “combination” or overlay districts layer additional, site‑specific standards on top of the base zoning shown on the Napa County Zoning map. Overlays can tighten minimum lot sizes, restrict development near airports, set affordable‑housing standards on designated sites, and tailor uses near parks or long‑standing restaurants. Overlays prevail where they conflict with base district standards, and they must be read alongside countywide land use, development standards, and any required design review findings.

Plain-English rule of thumb: If your zoning label includes a colon (like “AW:B‑5” or “RS:AC”), the letters after the colon are an overlay that adds rules on top of the base district (§ 18.08.160 ).

The overlay districts Napa County uses today

Napa County’s zoning code establishes the following “Combination Zoning Districts” for unincorporated areas: :B, :AC, :HR, :UR, :PS, :SWP, and :AH (§ 18.12.010 ).

:B Building Site Combination District

  • Purpose: Require larger minimum lot areas than the base district where site or service conditions warrant (§ 18.72.010 ).
  • Typical permitted uses: Whatever the base district allows; the overlay doesn’t add new uses—it adjusts site size (§ 18.72.020–.030 ).
  • Key dimensional standard:
    • Minimum lot area is set by the suffix in the zone label (e.g., :B‑5 = minimum 5 acres). This replaces the base district’s minimums where shown (§ 18.72.040–.050(A) ).
    • Note: Qualifying urban lot splits under Chapter 17.17 are explicitly not subject to the :B minimum parcel size (§ 18.72.050(B) ).
  • Where it applies: As mapped on parcels with constraints like topography or limited services (§ 18.72.010 ).

:AC Airport Compatibility Combination District

  • Purpose: Keep land uses, densities, and building features compatible with operations and safety at Napa County public‑use airports (§ 18.80.010 ).
  • Typical permitted uses: Base zoning uses continue, but projects must meet airport compatibility criteria from the Countywide ALUCP (§ 18.80.020–.040 ; ).
  • Key standards and procedures:
    • The :AC overlay controls where it conflicts with base zoning (§ 18.80.020 ).
    • Compatibility zones and intensity criteria for Angwin-Parrett Field and Napa County Airport apply in addition to base standards (§ 18.80.030–.040 ; ).
    • Applies to projects seeking plan or map approvals, rezoning, variances, use permits, subdivision, or a design review permit (§ 18.80.080 ).
    • Certain actions and any heights over ALUCP limits must be referred to the Airport Land Use Commission (ALUC) for consistency review (§ 18.80.090(A) ).
    • For design review approvals in :AC, decision-makers must find ALUC design requirements are met; ALUC consistency can be overridden only by a two‑thirds Board vote with specific state‑law findings (§ 18.80.090(B) ).
  • Where it applies: Parcels within airport influence areas shown on the zoning map with the :AC suffix (§ 18.80.020 ).

:AH Affordable Housing Combination District

  • Purpose: Implement Housing Element policies by setting site‑specific development frameworks for designated “Specified Priority Housing Development Sites” (§ 18.82.010(A)–(B) ; § 18.82.020 ).
  • Typical permitted uses: Residential projects meeting overlay affordability and site standards; parcels may develop either under base zoning or under :AH standards, but not both (with special minimum density for 2023 sites) (§ 18.82.010(E) ; § 18.82.040(A) ).
  • Key dimensional standards:
    • 2023 Spanish Flat site(s): Minimum density 20 du/ac; maximum 25 du/ac (§ 18.82.050(D) ).
    • 2009 designated sites: Density ranges by site (e.g., Angwin up to 25 du/ac; Moskowite Corner up to 10 du/ac; Spanish Flat up to 25 du/ac) (§ 18.82.050(C) ).
    • Affordability: Ownership projects must include moderate-income units; 2023 sites must include at least 20% low‑income units, with 40‑year affordability controls (§ 18.82.030(A)–(B) ; ).
  • Process:
    • Projects that meet all :AH standards (affordability, development standards, densities, mitigation) are approved ministerially at building permit—no discretionary CEQA project review (§ 18.82.090 ).
    • Utilities: “Will serve” letters required (§ 18.82.110 ).
  • Where it applies: Only to mapped Housing Element sites identified in § 18.82.020 (§ 18.82.020 ).

:UR Urban Reserve Combination District

  • Purpose: Flag parcels within a city sphere/urban limit where further urbanization should occur upon annexation, consistent with the General Plan (§ 18.100.010 ).
  • Typical permitted uses:
    • Uses allowed by right in the underlying zone (except telecommunication facilities) remain permitted; certain care uses may proceed with a use permit if also allowed by the base zone (§ 18.100.020(A)–(B) ).
    • Otherwise, additional development is restricted unless annexed (§ 18.100.020(C) ).
  • Nonresidential path without annexation: May proceed with a use permit if findings show city‑policy consistency, a denied annexation request within one year, and lack of reasonable use otherwise (§ 18.100.030(A)(1) ).
  • Where it applies: Parcels labeled with :UR inside adopted spheres/urban limits (§ 18.100.010 ).

:PS Agricultural Produce Stand Combination District

  • Purpose: Allow on‑site/outreach sale of agricultural produce and related items—and limited kid‑focused animal activities—on lands historically used for such purposes in Agricultural Watershed districts (§ 18.102.010 ).
  • Typical permitted uses:
    • Base‑district by‑right and use‑permit uses, plus on‑parcel sale of produce grown on or off premises, related items, and children’s pony/petting‑zoo activities; related stand buildings are allowed (§ 18.102.020(A)–(C) ).
    • With a use permit: Delicatessens with outdoor BBQ; wine tastings accessory to a lawful produce stand (§ 18.102.040 ).
  • Key standards: Base district development rules otherwise apply (§ 18.102.030 ).
  • Where it applies: Mapped AW parcels historically used for produce stands (§ 18.102.010 ).

:HR Historic Restaurant Combination District

  • Purpose: Preserve the ability of specific long‑standing restaurants to continue with defined seating, while controlling expansion (§ 18.103.010 ).
  • Typical permitted uses:
    • Base‑district uses continue; restaurants existing on April 22, 1998, may operate up to 200 seats if the parcel lawfully had at least 200 seats on November 5, 1985; related on‑site wastewater facilities are allowed (§ 18.103.020(C)–(D) ).
    • Expansion of buildings, parking, or patio areas beyond what existed on April 22, 1998, requires a use permit (§ 18.103.020(E), § 18.103.030 ).
  • Key standards: Base district rules apply, except as modified by the overlay’s seating and expansion provisions (§ 18.103.040 ).
  • Where it applies: Only on mapped parcels that meet the historic seating criteria (§ 18.103.010–.020 ; ).

:SWP Skyline Wilderness Park Combination District

  • Purpose: Tailor allowed uses within/adjacent to Skyline Wilderness Park, diverging from standard AW allowances (§ 18.90.010 ).
  • Typical permitted uses: Agriculture; parks and rural recreation; and campgrounds on public lands—subject to Chapter 18.104 park standards and a Board‑adopted Park Master Plan (§ 18.90.020(A)–(C) ; § 18.104.340–.350 ).
  • Key standards: Outdoor recreation uses must meet general and environmental performance standards (water/sewer, access, buffers, lighting, noise, aesthetics) (§ 18.104.340–.350 ).
  • Where it applies: Parcels mapped with :SWP near Skyline Wilderness Park (§ 18.90.010–.020 ).

Retired or reserved overlay chapters (for context)

  • Former :V Viewshed Protection Combination District repealed; viewshed protections now live in the countywide Viewshed Protection Program in Chapter 18.106 (§ 18.101 Editor’s note; § 18.106.010–.020 ; ).
  • Former FR Fire Risk and GR Geological Risk overlays were repealed and chapters reserved (§ 18.84, § 18.88 Editor’s notes ; ).

Quick reference table

Overlay What it does (in practice) Typical project triggers Code Reference
:B Building Site Raises the minimum lot area above the base zone (e.g., B‑5 = 5 acres) Lot line adjustments, subdivisions, parcel splits (SB 9 urban lot splits are exempt from :B minimum) § 18.72.010, .040–.050
:AC Airport Compatibility Applies ALUCP use, density, height, and design compatibility near airports; overlay controls over base zoning Any plan/map amendment, rezoning, variance, use permit, subdivision, or design review; ALUC referral for certain actions and over‑height § 18.80.020–.040, .080–.090 ;
:AH Affordable Housing Sets density/affordability and site standards on designated Housing Element parcels; can provide ministerial path New housing on mapped sites; building permits if all overlay criteria met § 18.82.010–.050, .090–.110 ; ; ;
:UR Urban Reserve Limits new development pending annexation; allows narrow nonresidential path with findings Any nonresidential project seeking a use permit within a city sphere/urban limit § 18.100.010–.030
:PS Produce Stand Allows farm stands (produce from on/off site) and, with a permit, BBQ delis and wine tastings Establishing/expanding produce stands or related accessory uses § 18.102.010–.040
:HR Historic Restaurant Grandfathers up to 200 seats for qualifying legacy restaurants; expansions need a permit Restaurant seating/area changes; wastewater tied to restaurant § 18.103.010–.040 ;
:SWP Skyline Wilderness Park Restricts uses to agriculture, parks/rural recreation, and public‑land campgrounds with park standards Parks/recreation projects; campgrounds on public land § 18.90.010–.020; § 18.104.340–.350 ;

Practical guidance for applicants

  • Always read overlays with the base district and the county’s Schedule of Zoning District Regulations; overlays can replace base minimums like lot size, while other base standards still apply (§ 18.104.010; § 18.72.050(A) ; ).
  • Near airports, plan for ALUCP consistency and factor in added design review findings specific to airspace protection (§ 18.80.080–.090 ; ).
  • On :AH sites, align your density and affordability program early; qualified projects can move ministerially at building permit, but still must meet site standards and mitigation (§ 18.82.030–.050, .070, .090 ; ).
  • For legacy restaurants in :HR, document historic seating and site conditions to avoid triggering a use permit for “expansion” (§ 18.103.010–.030 ; ).
  • For :PS stands, mind accessory activity limits and secure the appropriate use permit for BBQ delis or tastings; coordinate with signage and on‑site parking standards where applicable (§ 18.102.020–.040 ).

Checklist

  • Confirm the parcel is in unincorporated Napa County and identify all overlays in the zoning label on the official map (§ 18.12.020 ).
  • Pull applicable base district standards and the county’s Schedule of Zoning District Regulations (§ 18.104.010 ).
  • If the label includes :B, verify the mapped minimum lot size (e.g., B‑5, B‑10) and whether your action implicates it; note SB 9 urban lot splits are exempt from the :B minimum (§ 18.72.040–.050(B) ).
  • If within :AC, identify the ALUCP compatibility zone and prepare ALUC materials; confirm whether design review will need ALUC‑related findings (§ 18.80.030–.040, .080–.090 ; ).
  • If on a mapped :AH site, set project density/affordability to overlay targets; assemble the affordable housing plan and utility “will serve” letters (§ 18.82.030, .050, .090–.110 ; ; ).
  • For :UR, determine whether annexation is required or whether a nonresidential use permit path is feasible (§ 18.100.020–.030 ).
  • For :PS or :HR, inventory historic use conditions (prior seats, prior stand use) and flag any “expansion” that would require a use permit (§ 18.102.020–.040; § 18.103.010–.030 ; ).
  • Check related processes and standards like variances, signage, and landscaping as your site plan evolves.

Risks & Ambiguities

Issue Why it matters What to verify
Airport ALUCP updates The :AC overlay incorporates an external plan with zones/criteria that can change Current ALUCP exhibit and your parcel’s compatibility zone; whether ALUC referral is required (§ 18.80.030–.040, .090 ).
“Expansion” under :HR Even minor site or seating changes may need a use permit Document existing seating, buildings, patios, and parking as of April 22, 1998 (§ 18.103.020–.030 ).
Historic use for :PS Overlay eligibility is tied to historically used lands Evidence of historic produce stand use; scope of accessory tasting/BBQ with required permits (§ 18.102.010, .040 ).
Dual standards on :AH sites You must choose either base zoning or :AH standards (with special minimum density for 2023 sites) Selected development path, density, affordability commitments, and mitigation compliance (§ 18.82.010(E), .050(D), .090 ; ; ).
Urban Reserve limits :UR can block additional development absent annexation Whether annexation is planned/feasible; if not, whether nonresidential findings can be met (§ 18.100.020–.030 ).
Overlap with countywide programs Viewshed rules apply countywide, not as an overlay Whether Chapter 18.106 (Viewshed) affects your hillside/site design (§ 18.106.010–.020 ).

Plain-English Summary

In Napa County’s unincorporated areas, overlay districts fine‑tune what you can build and how—often adding bigger lot sizes (:B), airport‑safety limits (:AC), or special rules for affordable‑housing sites (:AH). Read your full zoning label, then check the overlay chapter for extra rules and processes—especially ALUC referrals near airports and use‑permit triggers for legacy restaurants (:HR) and produce stands (:PS). When in doubt, verify with the County.

Source References

  • § 18.08.160 (definition of combination zoning district)
  • § 18.12.010–.020 (districts established; official zoning map)
  • § 18.72.010–.050 (:B Building Site)
  • § 18.80.010–.090 (:AC Airport Compatibility) ; ;
  • § 18.82.010–.110 (:AH Affordable Housing) ; ; ; ; ;
  • § 18.100.010–.030 (:UR Urban Reserve)
  • § 18.102.010–.040 (:PS Agricultural Produce Stand)
  • § 18.103.010–.040 (:HR Historic Restaurant) ;
  • § 18.90.010–.020 (:SWP Skyline Wilderness Park) ; and related § 18.104.340–.350 (recreation standards)
  • § 18.101 (repealed :V Viewshed overlay) and § 18.106 (Viewshed Protection Program) ;
  • § 18.104.010 (Schedule of Zoning District Regulations)

Sources

Retrieved passages

  • Napa County Zoning Code (§ 11) Medium relevance
  • Napa County Zoning Code (§ 2) Medium relevance
  • Napa County Zoning Code (§ 1) Medium relevance
  • Napa County Zoning Code (Chapter 18.124) Medium relevance
  • Napa County Zoning Code (Chapter 18.66) Medium relevance
  • Napa County Zoning Code (§ 1) Medium relevance
  • Napa County Zoning Code (Section 18.104.230) Medium relevance
  • CBC § 18.108.030 (Section 18.108.030) Medium relevance
  • CBC § 44 (chapter and) Medium relevance
  • Napa County Zoning Code (§ 1) Medium relevance
  • Napa County Zoning Code (chapter as) Medium relevance
  • Napa County Zoning Code (§ 11) Medium relevance
  • Napa County Zoning Code (Chapter 18.108) Medium relevance
  • Napa County Zoning Code (§ 5) Medium relevance
  • Napa County Zoning Code (§ 18) Medium relevance
  • Napa County Zoning Code (§ 5) Medium relevance
  • Napa County Zoning Code (§ 3) Medium relevance
  • Napa County Zoning Code (Chapter 18.12) Medium relevance
  • Napa County Zoning Code (Chapter 18.88) Medium relevance
  • Napa County Zoning Code (§ 1) Medium relevance
  • Napa County Zoning Code (Chapter 18.100) Medium relevance

Cited sections

Frequently asked questions

How do I know if an overlay applies to my unincorporated Napa County parcel?

Check the official zoning map for a colon in your zoning label (e.g., “AW:B‑5” or “RS:AC”). The code lists all overlays and the map is the final authority (§ 18.12.010–.020; § 18.08.160 ; ).

What does “:B‑5” mean in Napa County?

It’s the Building Site overlay requiring a minimum lot area of 5 acres, superseding the base zone’s minimum. Other base standards still apply (§ 18.72.040–.050(A) ).

I’m near Napa County Airport—what extra steps apply?

In the :AC overlay, your project must meet ALUCP compatibility. Many applications must be referred to the ALUC, and design review must find ALUC design requirements are met (§ 18.80.080–.090 ; ).

Can I choose base zoning instead of :AH rules on a designated housing site?

Yes—projects can follow either base zoning or :AH standards, but not both; however, the 2023 Spanish Flat site must develop at 20–25 du/ac regardless. Qualifying :AH projects can be approved ministerially at building permit (§ 18.82.010(E); § 18.82.050(D); § 18.82.090 ; ; ).

What’s allowed at a produce stand under :PS?

Sale of agricultural produce grown on or off site and related items is allowed; with a use permit, accessory delicatessens with outdoor BBQ and wine tastings are also allowed (§ 18.102.020–.040 ).

I manage a legacy restaurant—can I add seats or expand the patio?

If your parcel qualifies under :HR, up to 200 seats are allowed without a use permit; any expansion of structures, parking, or patio beyond what existed on April 22, 1998, requires a use permit (§ 18.103.020–.030 ).

How does the Urban Reserve (:UR) overlay affect development?

:UR generally limits added development until annexation, with a narrow path for nonresidential projects if specific findings are made (including consistency with city policies and a denied annexation request) (§ 18.100.020–.030 ).

Do overlay rules change my parking or sign requirements?

Overlays rarely replace functional standards like parking or signage. Expect to meet both overlay limits and the base district’s development standards (§ 18.104.010; overlay chapters as cited ).

Are viewshed protections still an overlay?

No. The former :V overlay was repealed; viewshed protections are now countywide under Chapter 18.106 (Viewshed Protection Program) (§ 18.101 Editor’s note; § 18.106.010 ; ).

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