Napa County Zoning, Planning & Building Codes

Last reviewed: July 6, 2026

Overview

Napa County regulates land use only in the unincorporated areas. The controlling ordinance is Title 18 of the Napa County Code (Zoning), which ties local regulations to the County’s General Plan and establishes all base districts and overlays, their permitted uses, and the permit paths used to review projects (§ 18.04.010; § 18.12.010; § 18.12.080). If you’re new to Napa County, start by confirming your property’s base zoning and any “combination” (overlay) districts, then check the countywide rules on setbacks, height, coverage, development standards, parking and design review that layer on top (§ 18.12.020; § 18.12.070; § 18.104.010; § 18.112.020).

Most parcels in unincorporated Napa are in agriculture-first districts. The AP and AW districts require very large minimum parcel sizes (40 ac in AP; 160 ac in AW) and treat agriculture as the predominant use, with urban-scale development intentionally constrained (§ 18.16.010; § 18.104.010).

How Napa County’s code is organized

• Title and purpose. Title 18 – Zoning – implements the General Plan and California Government Code consistency requirements (§ 18.04.010).
• Base and overlay districts. The code lists every base district (AP, AW, RS, RM, IP, GI, etc.) and combination overlays (e.g., :AC Airport Compatibility, :AH Affordable Housing, :B Building Site) (§ 18.12.010).
• Where the rules live:
  • District-specific rules begin where uses “commence” for each district and are cross-summarized in the countywide “Schedule of Zoning District Regulations” table at Development Standards (§ 18.12.070; § 18.104.010).
  • Countywide site and access constraints include [Road Setbacks] (§ 18.112.020 et seq.; highway and arterial distances at § 18.112.040 and § 18.112.070) and the Viewshed Protection Program for hillside/ridgeline settings (§ 18.106.010).
  • Permit procedures appear in distinct chapters: use permits (§ 18.124.010–.080), administrative permits (§ 18.126.010–.030), and ministerial [site plan approval] (§ 18.140.010).
  • Special area programs include the Napa Pipe zoning chapter (§ 18.66.010–.320) and the Airport Compatibility overlay (:AC) with ALUC referral steps (§ 18.80.020; § 18.80.080–.100).

Zoning district families

Napa’s district structure is agriculture-forward, with limited urban districts in small unincorporated “urban bubbles.”

• Agriculture and resource districts

  • AP — Agricultural Preserve. Minimum parcel generally 40 ac; agriculture is the predominant land use; certain single‑family and agricultural accessory uses allowed; existing pre‑1974 wineries recognized with limits on expansion (§ 18.16.010; § 18.16.020; § 18.104.010).
  • AW — Agricultural Watershed. Minimum parcel generally 160 ac; protects watershed, reservoirs and tributaries; similar allowed uses as AP with watershed emphasis (§ 18.20.010–.020; § 18.104.010).
  • TP — Timber Preserve. Manages timberlands and allows timber, grazing, and utility lines; other uses only by permit (§ 18.68.010–.030).

• Residential districts

  • RS — Residential Single. Typical minimum lot 8,000 sf, 20 ft front, 6 ft side, 20 ft rear, and up to 50% coverage; max height 35 ft (§ 18.104.010; cross‑refs in § 18.52.050).
  • RM — Residential Multiple. Similar yards to RS, with 40% maximum coverage; multi‑family is allowed in areas with services (§ 18.60.010; § 18.60.020; § 18.104.010).
  • RC — Residential Country. Larger-lot residential with agricultural compatibility; see table for setbacks and height (§ 18.104.010).

• Commercial and industrial districts

  • CL / CN / MC. Limited and neighborhood commercial, and marine commercial along the Napa River or near Lake Berryessa; standards and performance criteria supplement the base table (§ 18.28.010–.030; § 18.32.070–.080; § 18.34.010; § 18.34.080–.100; § 18.104.010).
  • I — Industrial and GI — General Industrial. Typical 20 ft yards, max 35% (I) or 35–50% (GI) coverage, 35 ft height; GI has district‑specific yard and landscaping rules (§ 18.104.010; § 18.44.040; § 18.44.060; § 18.44.110).
  • IP — Industrial Park. Often within the Airport Industrial Area; minimum lot 5 ac (with smaller lots allowed in unified plans), 35% site coverage baseline, with tailored circulation and improvement standards in the specific‑plan area (§ 18.40.040; § 18.40.140).

• Planned and public districts

  • PD — Planned Development. Mixes residential, educational, and support commercial subject to a development plan and use permit; residential/commercial proportions are capped and unified design is required (§ 18.48.030–.060; § 18.104.060).
  • PL — Public Lands. Siting standards address landscaping, signage and drainage; uses aligned with public/quasi‑public services (§ 18.50.010; § 18.50.060–.110).

• Special area district

  • NP — Napa Pipe (NP‑MUR‑W / NP‑IBP‑W / NP‑IBP). A project‑based set of districts that must follow adopted design guidelines and a development plan; examples include an NP‑MUR‑W height up to 55 ft and tailored parking ratios for higher‑intensity mixed use (§ 18.66.010–.030; § 18.66.110; § 18.66.280).

Citywide development standards

Napa consolidates the “baseline” lot, yard, coverage, and height rules in a single schedule. Highlights:

• Agriculture/resource

  • AP: 40 ac min lot; 20/20/20 ft yards; 35 ft height (§ 18.104.010).
  • AW: 160 ac min lot; 20/20/20 ft yards; 35 ft height (§ 18.104.010).

• Residential

  • RS: 8,000 sf min lot; 20 ft front, 6 ft side, 20 ft rear; 50% coverage; 35 ft height (§ 18.104.010).
  • RM: 8,000 sf min lot; 20/6/20 ft yards; 40% coverage; 35 ft height (§ 18.104.010).

• Employment

  • I: 35% coverage; 20/20/20 ft yards; 35 ft height (§ 18.104.010).
  • GI: 35–50% coverage; setbacks vary by adjacency; 35 ft height, with GI‑specific setbacks and parking/landscape standards (§ 18.104.010; § 18.44.060; § 18.44.080–.110).
  • IP: 35–50% coverage depending on use; 35 ft height; small lots allowed under unified plans (§ 18.104.010; § 18.40.040).

• Roadway setbacks and viewsheds

  • Separate, countywide road setbacks apply regardless of base zoning, e.g., 70 ft from the centerline on State Routes 12/29/121/128; arterials and collectors have specified distances (§ 18.112.040; § 18.112.070). Hillside and ridgeline development must meet the Design Review-like criteria in the Viewshed Program (§ 18.106.010; exception process at § 18.106.070).

Parking and loading are addressed in their own chapter; district chapters (e.g., GI) and special districts (e.g., NP) add ratios and screening standards that can be more specific than the general code (§ 18.110.050–.070; § 18.44.080–.090; § 18.66.280–.300).

Specific plans & overlays

• Airport Industrial Area and ALUC overlay. Projects in the airport influence area use the :AC overlay and must be consistent with the Countywide Airport Land Use Compatibility Plan; design review approvals must include ALUC consistency findings and follow the ALUC referral process (§ 18.80.020; § 18.80.080–.100).
• Napa Pipe (NP). A tailored chapter sets the NP‑MUR‑W, NP‑IBP‑W, and NP‑IBP districts; all development must conform to an approved development plan and design guidelines (§ 18.66.020; § 18.66.030).
• Affordable Housing (:AH). On designated “Specified Priority Housing Development Sites,” residential projects must meet a minimum and maximum density (20–25 du/ac for 2023 sites) and are processed ministerially for building permit if they satisfy the chapter’s standards (§ 18.82.010(E); § 18.82.090).
• Other combination districts. The code lists :B Building Site, :HR Historic Restaurant, :UR Urban Reserve, :PS Produce Stand, and :SWP Skyline Wilderness Park; their presence modifies the base standards in different ways. For example, :HR recognizes certain historic restaurant sites subject to companion standards (§ 18.12.010; § 18.103.040).

For a quick directory of these geographies, see Napa County Overlay Districts.

Building permits & review

• Determination and standards. Confirm zoning map designation and applicable standards, then consult the countywide schedule for lot size, yards, coverage, and height (§ 18.12.020; § 18.104.010).
• Ministerial site plan approval. Many by‑right uses require a ministerial [site plan approval] prior to building permit; if approved, it “automatically authorizes the issuance of a building permit” under Title 17 and the California Building Standards Code (§ 18.140.010).
• Discretionary permits. Uses not allowed by right require a use permit with findings on health/safety, General Plan consistency, and groundwater impacts, among others (§ 18.124.060–.070). Some districts (e.g., PD) also require a development plan that unifies architecture, landscaping, signage and phasing (§ 18.48.060; § 18.104.060).
• Environmental and corridor overlays. Apply Viewshed standards where hillside or ridgeline development is visible from designated roads (§ 18.106.010) and comply with countywide road setbacks (§ 18.112.020–.040).
• Signs. Signage is regulated countywide; special standards apply in the Airport Industrial Area and within NP, where design guidelines control sign form and illumination (§ 18.116.010; § 18.116.045; § 18.66.310).
• Nonconformities and variances. Existing, lawful uses and structures may continue under the Legal Nonconformities chapter (with limits on expansion and abandonment), and variances are processed per Chapter 18.128 (referenced in several chapters) (§ 18.132.010–.040; § 18.112.140).

State housing law in Napa County

• ADUs/JADUs. Accessory dwelling units are allowed in the AP, AW, RS, and RM families when the County’s ADU conditions are met (e.g., AP and AW expressly allow an ADU and one JADU where § 18.104.180 is satisfied) (§ 18.16.020(F); § 18.20.020(C); § 18.60.020(I)). State law further guarantees at least an 800 sf ADU with 4‑ft side/rear setbacks even where local standards are more restrictive; see California ADU law for state‑mandated minimums (Gov. Code summarized in ).
• Density bonus and inclusionary. Napa County implements state density bonus and operates an inclusionary/fee framework in Chapter 18.107 to align with Government Code § 65915; this chapter sets local purposes and procedures and defines “discretionary permit,” among other terms (§ 18.107.010; § 18.107.020).
• Streamlined affordable sites. On :AH “Specified Priority Housing Development Sites,” qualifying affordable projects are processed ministerially for building permits if they meet density and development standards (§ 18.82.090).

Snapshot of frequently used standards

• The AP district: 20 ft front/side/rear setbacks and 35 ft height; 40 ac minimum parcel (§ 18.104.010).
• The RS district: 20 ft front, 6 ft side, 20 ft rear, 50% coverage, 35 ft height; 8,000 sf minimum parcel (§ 18.104.010).
• The GI district: 35–50% coverage, 35 ft height; tailored setbacks and landscaping/screening; on‑site parking with specified ratios (§ 18.44.040; § 18.44.060; § 18.44.080–.110).
• The NP‑MUR‑W district: up to 55 ft building height; coverage/setbacks controlled by the NP design guidelines and development plan (§ 18.66.110; § 18.66.120).

Source References

• Title 18 – Zoning: code structure, district establishment, and applicability (§ 18.04.010; § 18.12.010; § 18.12.070–.080)
• Countywide Schedule of Zoning District Regulations and footnotes (§ 18.104.010)
• Agricultural districts (AP, AW) (§ 18.16.010–.020; § 18.20.010–.020)
• Residential districts (RS, RM) (§ 18.52.030–.050; § 18.60.010–.020)
• Industrial/Business districts (IP, GI) (§ 18.40.040; § 18.44.040; § 18.44.060; § 18.44.080–.110)
• Napa Pipe districts and standards (§ 18.66.010–.030; § 18.66.100–.130; § 18.66.280–.320)
• Road setbacks (§ 18.112.020; § 18.112.040; § 18.112.070)
• Viewshed Protection Program (§ 18.106.010; § 18.106.070)
• Permit procedures: site plan approval (§ 18.140.010), use permits (§ 18.124.060–.070), administrative permits (§ 18.126.010–.030)
• ALUC overlay and process (§ 18.80.020; § 18.80.080–.100)
• Affordable Housing (:AH) (§ 18.82.010; § 18.82.090)
• Legal nonconformities (§ 18.132.010–.040)