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Local zoning · Lake Forest

Lake Forest — Nonconforming Uses

Nonconforming Uses under the Lake Forest local zoning and planning code, with the controlling citations.

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Quick answer

In Lake Forest, a lawful nonconforming use may continue, but if it’s discontinued for 1 year, any future use must meet current zoning (§ 9.188.010(A)). Expansions are tightly limited to “ordinary” work under 10% of building value in any 12 months with no cubic volume increase (§ 9.188.010(C)). If a nonconforming building is destroyed beyond 25% of its value, it must be rebuilt to conform (§ 9.188.010(D)).

Last reviewed: July 25, 2026 · AI-generated analysis · General information, not legal advice · details

Compiled from Lake Forest's adopted code with AI research tools and grounded in the sources cited below. Verify with Lake Forest planning staff before relying on it.

Overview

Lake Forest regulates existing uses, buildings, and facilities that no longer match today’s zoning through express “nonconforming” rules in the City’s Zoning Code. The core standards appear in the Lake Forest Zoning Code Title 9, including carry-forward use rights, strict limits on expansion, and thresholds that force full compliance if a nonconforming building is destroyed. This page interprets those rules and how they apply across Lake Forest’s zoning districts.

The single most important rule: a lawful nonconforming use may continue, but if it stops for 1 year, it loses its status and any future use must comply with current zoning (§ 9.188.010(A)).

What “nonconforming” covers in Lake Forest

  • Nonconforming uses of land and buildings: grandfathered uses that don’t match today’s permitted uses may continue subject to time limits, alteration caps, and change-of-use constraints (§ 9.188.010).
  • Nonconforming structures: buildings that conform by use but not by today’s development standards (e.g., setbacks) face strict limits on additions/alterations (§ 9.188.020).
  • Nonconforming “facilities” under specialized chapters (e.g., communications): treated separately, with their own maintenance/modification rules (§ 9.162.120).
  • Subdivision context: in an urban lot split, the City will not force correction of an existing legal nonconforming zoning condition as a condition of approval (§ 7.50.050(J)(8)).

Use listings and permissions still flow from your base zoning district in the Land Use Matrix (§ 9.72.090(A)), and uses not listed as permitted/allowed are prohibited (§ 9.124.050). For broader context on how this interacts with your base zoning and approvals, see the city’s Lake Forest Zoning, Lake Forest Land Use, and Lake Forest Development Standards pages.

Citywide nonconforming rules — at a glance

Decision Point Rule Number/Threshold Applies To Code Reference
Discontinuance If a nonconforming use of land is discontinued, it loses protection after one year; future use must conform. 1 year Nonconforming use of land § 9.188.010(A)
Extension within a building A nonconforming use may extend throughout the building if no structural alterations are made (except those required by law or permitted under § 9.184.010). No structural alterations Nonconforming use in a building § 9.188.010(B)
Change to another nonconforming use Allowed only if the new use is of the same or “more restricted” classification; restriction is measured by the numerical parking requirement in Chapter 9.168. Parking-based classification Nonconforming use in a building § 9.188.010(B)
Structural alterations to a nonconforming building/use Enlargement/extension is prohibited unless converting to a permitted use; ordinary alterations under value cap are allowed if cubic volume is not increased. ≤ 10% of building value in any 12-month period; no volume increase Nonconforming building/use § 9.188.010(C)
Destruction threshold If damaged or destroyed beyond a percentage of value, the structure/use must comply with current zoning when rebuilt. More than 25% of value Nonconforming building § 9.188.010(D)
Valuation method and appeals Director determines value using appropriate data; appeal to City Council available. Director determination; appeal per Ch. 2.04 Valuation/appeals § 9.188.010(E)
Required business licenses/permits No use and occupancy certificate for a nonconforming use without evidence of required licenses/permits. Evidence required Nonconforming uses § 9.188.010(F)
Altering a structure that’s nonconforming to standards (but conforming by use) Additions/alterations/enlargements must fully comply with current development standards and all applicable regulations. Full current compliance Nonconforming structures (dimensional) § 9.188.020
Nonconforming “facilities” (special chapter) Lawful facilities accepted as legal nonconforming; ordinary maintenance allowed; certain federal-protected modifications must be approved; illegal facilities are nuisances subject to abatement. Federal 47 U.S.C. 1455; 47 C.F.R. 1.6100 Facilities under Ch. 9.162 § 9.162.120
Urban lot split applications City won’t require correction of a legal nonconforming zoning condition to approve an urban lot split. Nonconforming condition preserved at map approval Urban lot splits § 7.50.050(J)(8)

For related approvals that can affect expansion or relief from standards, see Lake Forest Design Review and Lake Forest Variances and Exceptions. Parking-based “restriction” classifications are tied to Lake Forest Parking.

Applicability by District (how nonconformity interacts with use permissions)

The nonconforming rules above apply citywide regardless of district. Your base district determines whether a use would be conforming today and frames any proposed change of use. Below are the districts shown in the City’s Land Use Matrix (§ 9.72.090(A)) and examples of typical permissions that help determine whether a use is currently conforming or not. Where “purpose,” “dimensional standards,” or exact geographic application are not established in the source materials below, that is noted.

C (Commercial)

  • How nonconforming rules apply: If you operate a legacy commercial use not permitted today in C, it may continue unless discontinued for 1 year (§ 9.188.010(A)). Expansion is constrained by the 10% in 12 months cap without cubic volume increase (§ 9.188.010(C)).
  • Typical permitted examples: Administrative office (P), Retail business (P), Pharmacy (P), Restaurant (P), Health club (P) (§ 9.72.090(A)).
  • Key dimensional standards: Not found in source materials.
  • Where it applies: Verify with the jurisdiction.

I (Industrial)

  • How nonconforming rules apply: Legacy industrial uses not permitted today may continue, subject to discontinuance and alteration limits (§ 9.188.010(A)–(C)). Change to another nonconforming use must be same/more restricted based on parking (§ 9.188.010(B)).
  • Typical permitted examples: Manufacturing (P), Distribution facility (P), Light auto repair (P), Emergency shelter (P with note), Research/testing lab (P) (§ 9.72.090(A)).
  • Key dimensional standards: Not found in source materials.
  • Where it applies: Verify with the jurisdiction.

PA (Planned Area)

  • How nonconforming rules apply: Uses must align with the adopted plan and current matrix. Nonconforming uses of buildings may change only within the parking-based restriction rule (§ 9.188.010(B)).
  • Typical permitted examples: Administrative office (P), Assembly of components (P), Museum (P), Medical office (P) (§ 9.72.090(A)).
  • Key dimensional standards: Not found in source materials.
  • Where it applies: Verify with the jurisdiction.

UA (Urban Activity)

  • How nonconforming rules apply: Same citywide nonconforming limits apply. Any structural enlargement of a nonconforming use is prohibited unless converting to a permitted use; small “ordinary” work is capped (§ 9.188.010(C)).
  • Typical permitted examples: Administrative office (P), Conference center (S), Movie theater (S), Restaurant (P), Retail business (P) (§ 9.72.090(A)).
  • Key dimensional standards: Not found in source materials.
  • Where it applies: Verify with the jurisdiction.

CAN

  • How nonconforming rules apply: Nonconforming uses in CAN districts are treated the same—continuance allowed, but change and expansion are limited (§ 9.188.010).
  • Typical permitted examples: Animal clinic/hospital (P with note), Public utility (S), Conservation area (P) (§ 9.72.090(A)).
  • Key dimensional standards: Not found in source materials.
  • Where it applies: Verify with the jurisdiction.

A1 (Agriculture 1)

  • How nonconforming rules apply: Nonconforming agricultural or non-agricultural uses may continue with the same citywide thresholds (§ 9.188.010).
  • Typical permitted examples: Agriculture (P), Grazing (P), Employee housing (P) (§ 9.72.090(A)).
  • Key dimensional standards: Not found in source materials.
  • Where it applies: Verify with the jurisdiction.

OS (Open Space)

  • How nonconforming rules apply: Legacy uses that don’t match today’s OS permissions may continue under § 9.188.010; restoration beyond the 25% destruction threshold triggers full conformity (§ 9.188.010(D)).
  • Typical permitted examples: Open space (P), Park (P), Riding and hiking trail (P) (§ 9.72.090(A)).
  • Key dimensional standards: Not found in source materials.
  • Where it applies: Verify with the jurisdiction.

Notes on prohibitions and special regulations that interact with nonconformity:

  • Uses not expressly permitted are prohibited (§ 9.124.050; § 9.236.040; § 9.228.050). A prohibited use can only persist if it qualifies as a lawful nonconforming use under § 9.188.010.
  • Some uses carry their own special regulations that must be met even when a use is conforming (§ 9.146.010). If you change from one nonconforming use to another, ensure those special standards are satisfied as applicable. For design-related review of changes, see Lake Forest Design Review. For overlay controls that may add standards, see Lake Forest Overlay Districts.

Practical interpretations

  • “More restricted” classification is defined by parking: If your proposed new nonconforming use requires the same or fewer parking spaces than the existing one per Chapter 9.168, a change may be allowed without losing nonconforming status (§ 9.188.010(B)). Coordinate early with the City on parking counts; see Lake Forest Parking.
  • Ordinary alterations limit is tight: In any rolling 12-month period, “ordinary” work on a nonconforming building is capped at 10% of the building’s value and cannot increase cubic volume (§ 9.188.010(C)). Larger expansions require converting to a conforming use.
  • Rebuild threshold is strict: Damage over 25% of value ends the nonconforming status upon rebuilding (§ 9.188.010(D)). The Director determines value and you can appeal to the City Council (Ch. 2.04) (§ 9.188.010(E)).
  • Dimensional nonconformities don’t expand: If your use is conforming but the building encroaches on a setback or other standard, any addition must fully meet current standards (§ 9.188.020). Relief, if any, runs through the City’s exceptions/CUP path (§ 9.73.064) and related Lake Forest Variances and Exceptions.
  • Urban lot splits preserve existing legal nonconforming zoning conditions at the map stage: You won’t be required to fix them just to record the split (§ 7.50.050(J)(8)). Other objective standards in that chapter still apply, including front setbacks and parking for split lots (§ 7.50.050).

Checklist

  • Confirm the use/building/facility was lawful when established (needed to qualify as “legal nonconforming”) (§ 9.188.010; § 9.162.120(A)).
  • Document continuous operation; avoid any discontinuance gap of 1 year or more for land uses (§ 9.188.010(A)).
  • For any change from one nonconforming use to another, show the new use is of the same or a more restricted parking classification per Ch. 9.168 (§ 9.188.010(B)).
  • For work on a nonconforming building/use, keep “ordinary” alterations within 10% of building value in any 12 months, with no cubic volume increase, unless converting to a conforming use (§ 9.188.010(C)).
  • If damage occurs, obtain the Director’s valuation and be prepared to conform if loss exceeds 25% of building value (§ 9.188.010(D)–(E)).
  • If your structure is nonconforming to development standards (e.g., setback), design any addition to fully meet current standards (§ 9.188.020); consult Lake Forest Development Standards).
  • Provide evidence of any required business licenses/permits to receive a use and occupancy certificate for a nonconforming business (§ 9.188.010(F)).
  • For communications or similar “facilities,” check Chapter 9.162 nonconforming provisions and any federal eligibility (§ 9.162.120).
  • For lot splits, note that legal nonconforming zoning conditions are not forced to be corrected at approval (§ 7.50.050(J)(8)); verify other objective standards like parking still apply.

Risks & Ambiguities

Issue Why it matters What to verify
Proving the use was lawful originally Only “lawful” uses can be nonconforming; illegal uses are not protected. Records of permits, business licenses, certificates, and occupancy history (§ 9.188.010; § 9.188.010(F)).
Measuring the one-year discontinuance A short lapse can terminate nonconforming rights. Dates of inactivity/closure; lease records; utility bills; City interpretation of “discontinued” (§ 9.188.010(A)).
Parking-based “restriction” test Whether a new nonconforming use is allowed depends on parking numbers. Required parking ratios for both uses per Ch. 9.168; City agreement on counts (§ 9.188.010(B)).
10%/12-month “ordinary alteration” cap Exceeding the cap or increasing volume can force full conformance. Building value determination; scope of work; cubic volume calcs (§ 9.188.010(C)).
25% destruction threshold Crossing the threshold ends nonconforming status. Director’s valuation method, data sources, and appeal timing (§ 9.188.010(D)–(E)).
Additions to setback/height nonconforming buildings Additions must fully comply with current standards. Current dimensional standards; potential for CUP exception per § 9.73.064; Design Review triggers (§ 9.188.020).
District applicability and dimensional standards District-specific standards shape what “conforming” means. Current district map/standards; Zoning and Development Standards pages; “Not found in source materials” here for purposes/dimensions.
Special-regulation uses and overlays Some uses need extra findings; overlays may add constraints. Applicable special regs (§ 9.146.010), any overlay standards; see Overlay Districts.
Urban lot split interplay Split approval won’t fix prior nonconformity but other standards still bite. Objective standards in § 7.50.050 (front setbacks, parking, screening) and parking applicability.

Plain-English Summary

Lake Forest generally lets a legal nonconforming use or building keep operating, but it cannot grow and it can easily lose that status if it stops for a year, is altered too much, or is heavily damaged. If your building encroaches on a setback, any new addition must meet today’s standards. Changing one nonconforming business to another is only allowed if the new one needs the same or fewer parking spaces than the old one.

Information Gaps

  • District purposes, exact dimensional standards (setbacks, heights, FAR), and mapped applicability by district: Not found in source materials.
  • Full residential district designations and permissions: Not found in source materials.
  • Detailed procedures/findings for § 9.184.010 cross-referenced in § 9.188.010(B) and CUP exception mechanics beyond § 9.73.064: Not found in source materials.

Source References

Sources

Source passages

  • Lake Forest Zoning Code (§ 7.50.050) Medium relevance
  • Lake Forest Zoning Code (§ 9.188.010) Medium relevance
  • CBC § 9.188.020 (§ 9.188.020) Medium relevance
  • Lake Forest Zoning Code (§ 9.162.120) Medium relevance
  • Lake Forest Zoning Code (§ 9.124.050) Medium relevance
  • Lake Forest Zoning Code (§ 9.146.010) Medium relevance
  • Lake Forest Zoning Code (§ 7.08.025) Medium relevance
  • Lake Forest Zoning Code (§ 9.72.090) Medium relevance
  • Lake Forest Zoning Code (§ 9.236.040) Medium relevance
  • Lake Forest Zoning Code (§ 9.228.050) Medium relevance
  • Lake Forest Zoning Code (§ 9.73.064) Medium relevance

Cited sections

Frequently asked questions

How long can a nonconforming use sit vacant in Lake Forest before it loses protection?

A nonconforming use of land that is discontinued for a period of one year must thereafter comply with current zoning. After that 1-year lapse, the prior nonconforming status cannot be resumed (§ 9.188.010(A)).

Can I rebuild a nonconforming building after a fire or other damage?

Only if the damage is at or below the threshold. If the building is destroyed to the extent of more than 25% of its value (as determined by the Director), the rebuilt structure and use must fully conform with today’s zoning (§ 9.188.010(D)–(E)).

May I expand a nonconforming business use that’s still operating?

Expansions are generally prohibited unless you convert to a conforming use. The code only allows “ordinary” alterations within 10% of building value in any 12-month period and without any increase in cubic volume (§ 9.188.010(C)).

Can I change one nonconforming use to a different one?

Possibly. A nonconforming use of a building may be changed to another nonconforming use only if the new use is of the same or a “more restricted” classification, which Lake Forest defines by the numerical parking requirement in Chapter 9.168 (§ 9.188.010(B)).

What if my building meets the use rules but doesn’t meet setbacks or height?

It’s a nonconforming structure (dimensional). You may alter or add to it only to the extent the alteration fully complies with current development standards and all applicable regulations (§ 9.188.020). Do not extend the encroachment.

Do I need current business licenses to keep operating a nonconforming business?

Yes. The City will not issue a use and occupancy certificate for the continued occupancy of a nonconforming business unless you show you hold (or can obtain) any required licenses or permits (§ 9.188.010(F)).

How are nonconforming wireless or communications facilities treated?

Legal nonconforming facilities are accepted and may receive ordinary maintenance; certain modifications must be approved as required by federal law (47 U.S.C. 1455; 47 C.F.R. 1.6100). Illegal facilities are public nuisances subject to abatement (§ 9.162.120).

Does an urban lot split force me to fix an old nonconforming condition?

No. An urban lot split is approved without requiring a legal nonconforming zoning condition to be corrected. Other objective standards in that chapter still apply (§ 7.50.050(J)(8)).

Are uses not listed in my district allowed if they were there before?

If the use was lawfully established, it may be protected as a nonconforming use under § 9.188.010. New uses not expressly permitted are prohibited (§ 9.124.050; see also § 9.236.040; § 9.228.050).

Can I get an exception to development standards for a nonconforming site?

The City allows exceptions to certain development regulations via CUP per § 9.73.064. This is separate from nonconforming rights and requires meeting CUP criteria.

General information, not legal advice.

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