Local zoning · St. Helena

St. Helena — Nonconforming Uses

Nonconforming Uses under the St. Helena local zoning and planning code, with the controlling citations.

Last reviewed: July 6, 2026

Overview

St. Helena’s nonconforming rules live in Title 17 Zoning Code — Chapter 17.09 Nonconforming Provisions. They govern how a use, lot, or structure that was legal when created but no longer meets current St. Helena Zoning or St. Helena Development Standards may continue, change, be rebuilt, or be phased out. The City allows lawful nonconformities to continue subject to strict limits on expansion, abandonment, and reestablishment, with a formal “certificate” process available to lock in the present extent of a lawful nonconforming use. See § 17.09.010–§ 17.09.070 .

The single most important rule: a nonconforming use that is discontinued for 60 continuous days is deemed abandoned, regardless of intent; reestablishment requires Planning Commission review under set criteria in § 17.09.030(D) .

What St. Helena regulates as “nonconforming”

The City’s purpose is to allow lawful nonconformities to continue while encouraging their eventual elimination and preventing their reestablishment after abandonment or major destruction (the “50% rule” for structures) per § 17.09.010 and § 17.09.050 .
Continuation and maintenance are allowed indefinitely, but enlargement or alteration is limited by Chapter 17.09; nonconforming lots may still be used if new work meets current standards in the applicable district per § 17.09.020 and § 17.09.040 .
“Nonconforming use,” “nonconforming structure,” and “nonconforming lot” are defined in Division V (Definitions) of Title 17, which align with the above framework; a nonconforming use is a lawful use that no longer conforms to current district use regulations per § 17.32 (Definitions) .

Core Citywide Rules for Nonconforming Uses, Lots, and Structures

Continuation: Lawfully established nonconforming uses, structures, and lots may continue and be maintained subject to Chapter 17.09 limits. No enlargement unless expressly allowed by Chapter 17.09 per § 17.09.020 .
Nonconforming uses:
- No extension to other parts of the site/building; limited residential exceptions may be considered via CUP per § 17.09.030(A) .
- Change from one nonconforming use to another requires a CUP, a finding that the new use is more consistent and less intensive, and an amortization schedule to discontinue the nonconformity per § 17.09.030(B) .
- Once changed to a conforming use, the nonconforming use cannot be reestablished per § 17.09.030(C) .
- Abandonment occurs after 60 continuous days (intent does not matter). Reestablishment paths differ depending on whether a CUP was required or approved; Planning Commission holds a noticed public hearing and applies specific criteria per § 17.09.030(D) .
- Time extensions: one-year extension for closures due to seismic retrofit with approval by the Community Development Director per § 17.09.030(E) .
- “Certificate of Present Extent of Legal Nonconformity for Uses” is available; the owner bears the burden of proof; the Community Development Director issues a written determination, can refer to the Planning Commission for hearing, and files copies with the Napa County Assessor per § 17.09.030(F) .
Nonconforming lots: May be used/developed for conforming uses if new work meets current standards. One single-family dwelling is allowed on a lawful nonconforming lot in districts where single-family is permitted, provided current standards are met per § 17.09.040 .
Nonconforming buildings/structures:
- No reconstruction/expansion unless the new work conforms to the current district standards; remodeling is allowed if it does not increase the degree of nonconformity per § 17.09.050(A)–(B) .
- “50% rule”: If damage/destruction ≤50% of gross floor area, it may be reconstructed to its original condition; if >50%, rebuild must meet current standards unless a CUP is approved within one year to reconstruct to the original or other nonconforming condition per § 17.09.050(C) .
- Seismic/code compliance work is allowed when exclusively to meet applicable safety/building requirements, as determined by the Chief Building Official per § 17.09.050(D); see also California Building Standards Code for separate state building rules .
Illegal nonconforming uses/structures are a public nuisance and subject to abatement per § 17.09.060 .
Nonconforming signs have their own timelines and removal/repair rules per § 17.09.070; e.g., a legally nonconforming permanent sign may continue for up to five years after the effective date or seven years from erection (whichever is shorter), with removal required if abandoned/destroyed beyond one-half value per § 17.09.070(A)–(B) . See also St. Helena Signage.

How nonconformities are judged against base district rules

Understanding what is “nonconforming” starts with each base district’s permitted uses and standards. St. Helena’s base districts are organized in Division III of Title 17, with St. Helena Land Use tables and St. Helena Development Standards driving compliance. Below are summaries (purpose, typical uses, selected dimensional standards), so you can tell when a legacy use deviates from today’s rules.

Residential districts — LR-1A, LR, MR, HR

Purpose and typical uses: Low-density through high-density residential; accessory uses like home occupations and pools are allowed by right across districts per § 17.16.020(A) .
Key dimensional standards: Density ranges from 1 du/ac (LR‑1A) up to 16.1–28 du/ac (HR); minimum lot widths often 70 ft (LR‑1A/LR) and 45 ft (MR/HR); building heights generally 30 ft (LR‑1A/LR/MR) and 42 ft/3 stories (HR); front setbacks generally 20–30 ft depending on height and district per § 17.16.030(B) and Table 17.16.030(C) .
Where it applies: Citywide residential neighborhoods mapped in the zoning map (see Division III overview) .
Practical nonconformity cue: A duplex in LR (if not allowed today on a given lot) would be a nonconforming use; a house encroaching into today’s front setback would be a nonconforming structure under § 17.09.050 .

Commercial & Mixed-Use — CB (Commercial Business), SC (Service Commercial), MU (Mixed-Use)

Purpose and typical uses: Retail, services, entertainment, and mixed residential on Main Street and corridors. Use permissions vary; e.g., service stations require CUP in CB/SC; various food/entertainment uses are regulated with end notes per § 17.17.020(A) .
Key dimensional standards: FAR caps include Max. 2.0 (CB), 0.50 (SC), 1.0 (MU); lot minimums 5,000–10,000 sq ft; complex height and frontage rules vary by street frontage and proximity to residential per § 17.17.030(B) .
Where it applies: Downtown/Main Street (CB), service corridors (SC), and designated mixed-use nodes (MU) per the zoning map (Division III) .
Practical nonconformity cue: A now-prohibited drive-through in CB is a classic nonconforming use; an older storefront failing current frontage/height rules is a nonconforming structure per § 17.09.050 .

Business & Industrial — BPO (Business Professional Office), I (Industrial)

Purpose and typical uses: Office, research, warehousing, manufacturing (with permit tiers). Example: warehousing is permitted in I and conditional in some cases; hazardous uses often require CUP per § 17.18.020(A) and end notes .
Key dimensional standards: Not found in retrieved materials.
Where it applies: Employment areas per the zoning map (Division III) .
Practical nonconformity cue: Legacy industrial in BPO may be a nonconforming use if no longer listed as permitted/conditional per § 17.09.030 .

Community Agriculture & Natural Resource — A‑20 (Twenty‑Acre Agriculture), W (Winery), WW (Woodlands & Watershed)

Purpose and typical uses: Agriculture, small wineries, and rural resource areas; winery accessory uses have specific limits and setbacks, some requiring CUPs near residences or scenic corridors per § 17.19.020(A) end notes .
Key dimensional standards: Heavily prescriptive. Highlights include minimum 20-acre lots (A‑20/W), stringent setbacks from waterways, and height limits generally 30–45 ft depending on district per § 17.19.030(B) .
Where it applies: Edges of the city where ag and resource protection predominate (Division III) .
Practical nonconformity cue: A pre-existing winery operation exceeding current setback or accessory use placement standards may be a nonconforming development; scope changes can trigger CUP/new review per § 17.09.050 and use table end notes .

Public & Open Space — PQP (Public/Quasi-Public), PR (Parks & Recreation), OS (Open Space)

Purpose and typical uses: Public facilities, parks, and stream-corridor open spaces; see broad institutional and recreation use allowances per § 17.20.020(A) and purpose statements per § 17.20.010 .
Key dimensional standards: FAR and coverage caps in PQP, generous setbacks in PR and OS, and waterway buffers per § 17.20.030(B) .
Where it applies: City parks, schools, and river/creek corridors (Division III) .
Practical nonconformity cue: A private commercial use persisting on a site now zoned OS would be a nonconforming use subject to the 60‑day abandonment rule per § 17.09.030(D)(1) .

Overlays and special plans

Overlays can add protections/limits (e.g., Historic Preservation Overlay, Flood Plain Overlay) and may affect whether a change from a nonconforming use to a conforming one also requires St. Helena Design Review or St. Helena Historic Preservation review. Example: historic properties and certain additions trigger major design review per HPO provisions and § 17.05.070 references in overlay rules .
Example of overlay interaction: development near Highway 29 may face added interior side or rear setback constraints referenced in commercial standards and the Highway 29 Specific Plan EIR notes (end notes to § 17.17.030(B)) — Verify parcel-specific overlays before asserting conformity .
Flood-plain proximity triggers CUP for some ag/winery activities (end note to § 17.19.020(A)). This doesn’t create a “nonconformity” by itself but can control future changes to a use/site .

ADUs and nonconforming conditions

St. Helena implements state ADU law so that an ADU generally cannot be denied just because an existing site has nonconforming zoning conditions that aren’t affected by the ADU, and the City can’t require you to “correct” those as part of an ADU permit. See ADU-specific provisions in § 17.22.030 and state ADU law summaries; for St. Helena’s ordinance text, see § 17.22.030(C)(4) defining “nonconforming zoning condition” and limiting denials tied to such conditions, and consult St. Helena ADUs for the local program .

Decision-Focused Table — Key Nonconforming Rules

Topic	City rule (plain English)	Code Reference
Continuation	Lawful nonconforming uses/structures/lots can continue, but expansions are tightly limited.	§ 17.09.020
Extending a nonconforming use	No extension to other parts of a building/site; limited residential expansion via CUP only.	§ 17.09.030(A)
Changing to another nonconforming use	CUP required; resulting use must be more consistent and less intensive; City sets an amortization end date.	§ 17.09.030(B)
Abandonment clock	60 continuous days of discontinuance = abandonment, regardless of intent.	§ 17.09.030(D)(1)
Reestablishment after abandonment (with prior CUP)	May resume the same use within six months if criteria (notice, business license, other approvals) are met.	§ 17.09.030(D)(2)(a)
Reestablishment after abandonment (CUP required but not held)	Must apply within 60 days of notice; Planning Commission applies CUP findings before resuming.	§ 17.09.030(D)(2)(b)
Reestablishment when use now prohibited	Only if strict criteria are met (special building design, >50% retrofit cost to conform, etc.).	§ 17.09.030(D)(2)(c)
Certificate of present extent	Formal administrative determination by Community Development Director; may be reviewed by Planning Commission; filed with Assessor.	§ 17.09.030(F)
Nonconforming structures: 50% rule	≤50% GFA destroyed: rebuild to original; >50%: comply with current code or seek CUP within one year to rebuild nonconforming.	§ 17.09.050(C)
Seismic/code work	Allowed if exclusively for safety/code compliance as determined by CBO.	§ 17.09.050(D)
Nonconforming lots	Conforming uses OK if all new work meets today’s standards; one single-family dwelling may be allowed on a lawful nonconforming lot in applicable districts.	§ 17.09.040
Signs	Nonconforming permanent signs have phase-out/removal timelines; historic signs may be exempt.	§ 17.09.070

Checklist

Confirm your site’s current base district and any overlays in Division III/IV of Title 17 and the zoning map; compare today’s use/standards to identify the nonconformity. See St. Helena Zoning and St. Helena Overlay Districts .
Document lawful status (permits, dates, business licenses) to support any nonconforming claim or certificate request under § 17.09.030(F) .
If a use paused operations, calculate the 60-day abandonment period and whether a 6‑month reactivation window applies (for uses with an approved CUP) under § 17.09.030(D); prepare for a Planning Commission hearing if reestablishment is needed .
For structure damage, obtain the Chief Building Official’s 50% determination and decide between by-right reconstruction or CUP to rebuild a nonconforming structure under § 17.09.050(C); coordinate any required St. Helena Design Review if a discretionary permit is pursued .
If planning a change from one nonconforming use to another, build findings that the new use is more consistent and less intensive and propose an amortization schedule under § 17.09.030(B) .
For ADUs, do not assume the City can force you to fix unrelated nonconforming conditions; check § 17.22.030 and St. Helena ADUs .
If signage is involved, plan for phase-out or conformance per § 17.09.070 and St. Helena Signage .

Risks & Ambiguities

Issue	Why it matters	What to verify
60-day abandonment clock	Missing the window converts a dormant use into an abandoned nonconforming use, raising the bar to reestablish.	Track dates; confirm applicability of the 6‑month resume window for uses with a CUP and whether your case needs a Planning Commission hearing under § 17.09.030(D) .
“Degree of nonconformity” increases	Some remodels are allowed only if they don’t increase nonconformity; expanding the wrong way could require full conformance.	Have a plan set showing no new or worsened nonconformities under § 17.09.050(B) .
50% destruction threshold	CBO’s determination controls whether you can rebuild to original condition or must meet current standards or seek a CUP.	Get the CBO’s written % loss and file any CUP within 1 year to preserve nonconforming reconstruction options per § 17.09.050(C) .
Changing to a “less intensive” nonconforming use	The City must find the new use more consistent and less intensive; otherwise you may be denied.	Prepare operational metrics (hours, employees, trips, noise, parking) for § 17.09.030(B) findings .
Overlay and historic triggers	Even if a use becomes conforming, overlays can add separate approvals (e.g., HPO design review).	Check overlays and St. Helena Historic Preservation; confirm any design review triggers noted in overlay standards .
ADU denials tied to unrelated nonconformities	State and local ADU rules limit denial based on unrelated zoning nonconformities.	Align with § 17.22.030; if an ADU is proposed, ensure any cited nonconformity is actually affected by the ADU work .
“Illegal” vs. “nonconforming”	Unlawful uses/structures are a nuisance and must be abated; they do not enjoy nonconforming protections.	Confirm the use/structure was lawful when established; see § 17.09.060 .

Plain-English Summary

If your property was legal when built but today’s rules would not allow it, St. Helena generally lets you keep using it — but you can’t expand the nonconforming parts, and if you stop using it for 60 days, it’s “abandoned” and harder to restart. If a nonconforming building is mostly destroyed, you usually must rebuild to current standards unless you get a timely CUP. When in doubt, ask the City for a “certificate” to lock down the official scope of your legal nonconformity, and expect Planning Commission review if you want to restart an abandoned use or swap one nonconforming use for another with less impact under § 17.09.030–§ 17.09.050 .

Source References

Title 17 Zoning Code — Division II & III overview (chapter index) — current through Ord. 26‑4 (May 12, 2026) — § 17.01–§ 17.34 (table of contents) .
Nonconforming Provisions — § 17.09.010–§ 17.09.070 (purpose; continuation; nonconforming uses; lots; buildings/structures; illegal nonconformities; signs) .
Residential districts — uses and standards — § 17.16.020–§ 17.16.030 (LR‑1A, LR, MR, HR) .
Commercial & Mixed‑Use districts — uses and standards — § 17.17.020–§ 17.17.030 (CB, SC, MU) .
Business & Industrial districts — uses — § 17.18.020(A) (BPO, I) .
Community Agriculture & Natural Resource — uses and standards — § 17.19.020–§ 17.19.030 (A‑20, W, WW) .
Public & Open Space — purposes, uses and standards — § 17.20.010–§ 17.20.030 (PQP, PR, OS) .
Historic/overlay references — HPO design review triggers and PD Overlay mechanics — § 17.05.070 (via overlay refs), § 17.21 (Overlays) excerpts; PD overlay standards and procedures (Division III overlay chapter) .
ADU interactions (nonconforming zoning conditions) — § 17.22.030 .

Sources

Retrieved passages

St. Helena Zoning Code (chapter provides) High relevance
St. Helena Zoning Code (Title 17) High relevance
St. Helena Zoning Code (Section 17.05.020) High relevance
St. Helena Zoning Code (Section 17.05.020) High relevance
St. Helena Zoning Code (Title 17) High relevance
CBC § 5 (Title 17) High relevance
St. Helena Zoning Code (Title 17) High relevance
St. Helena Zoning Code (Title 17) High relevance
St. Helena Zoning Code (title to) High relevance
St. Helena Zoning Code (Section 17021.6) Medium relevance
St. Helena Zoning Code (Title 17) Medium relevance
CBC § 66314 (§ 66314) Medium relevance
St. Helena Zoning Code (§ 5) Medium relevance
St. Helena Zoning Code (Title 17) Medium relevance
St. Helena Zoning Code (§ 66333) Medium relevance
St. Helena Zoning Code (Title 17) Medium relevance
St. Helena Zoning Code (§ 66314) Medium relevance
St. Helena Zoning Code (Title 17) Medium relevance
St. Helena Zoning Code (Title 17) Medium relevance
St. Helena Zoning Code (Section Section) Medium relevance

Cited sections

Official St. Helena code library

Frequently asked questions

What is a “nonconforming use” in St. Helena?

A lawful use that no longer matches today’s permitted uses in its zoning district is a nonconforming use. It may continue but cannot expand and faces strict limits if abandoned or changed to another use per § 17.09.030 .

How long can a nonconforming use be closed before it’s considered abandoned?

If given up, closed, or discontinued for 60 continuous days, it is considered abandoned, regardless of intent. Reestablishment requires a Planning Commission hearing under criteria in § 17.09.030(D) .

Can I switch from one nonconforming use to a different one?

Possibly. You need a CUP, and the new use must be more consistent with district uses and less intensive, and the City will set an amortization end date to discontinue the nonconformity under § 17.09.030(B) .

What if my nonconforming building is damaged?

If the Chief Building Official finds ≤50% of gross floor area was lost, you may rebuild to original. If >50% is lost, you must meet current standards or seek a CUP within one year to rebuild a nonconforming structure under § 17.09.050(C) .

How do I prove the scope of my legal nonconforming use?

Apply for a Certificate of Present Extent of Legal Nonconformity. The Community Development Director issues an administrative determination; it can be reviewed by the Planning Commission and is filed with the Napa County Assessor per § 17.09.030(F) .

Can the City force me to fix unrelated nonconforming conditions if I’m building an ADU?

Generally no. The ADU provisions limit denials based on unrelated nonconforming zoning conditions not affected by the ADU work. See § 17.22.030 and local ADU standards .

Do nonconforming signs get special treatment?

They have specific timelines. A legally nonconforming permanent sign may continue for up to five years after the effective date or seven years from erection (whichever is shorter), with removal if abandoned/destroyed beyond one-half value, per § 17.09.070(A)–(B) .

What if my lot doesn’t meet today’s size/width?

A conforming use and building can be established on a lawful nonconforming lot if all new work meets current standards; one single-family dwelling is allowed in districts that permit it, per § 17.09.040 .

Ask about any St. Helena property

Get a cited, plain-English answer on St. Helena zoning, setbacks, FAR, ADUs and permits — for any address.

Start Free Trial

More St. Helena zoning topics

St. Helena Zoning

St. Helena Land Use

St. Helena Development Standards

St. Helena Parking

St. Helena Design Review

St. Helena Overlay Districts

St. Helena Historic Preservation

St. Helena Signage

St. Helena Variances and Exceptions

St. Helena Landscaping and Screening

St. Helena overview