Lassen County — Nonconforming Uses

Last reviewed: July 6, 2026

Overview

In unincorporated Lassen County, the zoning ordinance recognizes “lawful” nonconforming uses and structures that were established before a zoning change and lets them continue under strict limits. Expansion, rebuilding after major damage, and lapses in operation are tightly regulated and can trigger full conformance with current zoning. The controlling rules live in Title 18 (Zoning), especially the dedicated chapter on nonconforming uses, plus several airport-approach overlay chapters that add specialized nonconformity rules for height and hazard near airports.

Bottom line: In unincorporated areas, a lawful nonconforming use can continue, but if it stops for one continuous year it’s presumed abandoned and must thereafter meet current zoning; expansion or major reconstruction generally requires discretionary approval. See § 18.120.040 and §§ 18.120.030–.050 .

What counts as a “nonconforming” use, building, or lot

• The lawful use of land that no longer matches the current zone can continue, but cannot be enlarged or expanded to a greater area unless this chapter’s requirements are first met (e.g., required approvals) per § 18.120.010 .
• A lawful use of a building or of land existing at the time of the zoning change can continue and be maintained without securing a new use permit or conditional use certificate, so long as all requirements of the nonconforming chapter are met, per § 18.120.020 .
• If a nonconforming building is damaged or destroyed by more than 75% of its assessed value, it may be reconstructed only if:
  • It’s a residential nonconforming use and you secure a certificate of conditional use under Chapter 18.114, with the application filed within one year of damage; or
  • It’s a nonresidential nonconforming use and you secure a use permit under Chapter 18.112, with the application filed within one year of damage, all per § 18.120.030 .
• If the actual operation ceases for one continuous year, the nonconforming use is presumed abandoned, and the property must thereafter comply with current zoning; the Planning and Building Director makes that determination, which can be appealed under Chapter 18.122 and § 18.120.080, per § 18.120.040 .
• Expansions/alterations:
  • Residential nonconforming uses may be enlarged/altered after securing a certificate of conditional use (Chapter 18.114) per § 18.120.050(1)(A) .
  • Nonresidential nonconforming uses may be enlarged/altered after securing a use permit (Chapter 18.112) per § 18.120.050(1)(B) .
• Ordinary maintenance up to 25% of assessed value in any one-year period is allowed without a discretionary approval; work over that threshold requires a certificate of conditional use (residential) or a use permit (nonresidential), per § 18.120.050(2) .
• If a building/use was formerly by-right and the new zoning would allow the same use by use permit or conditional use, then the use is treated as conforming and may continue without that permit (though it must meet all other code requirements), per § 18.120.050(3) .
• Projects already under construction before a zoning change can continue if a building permit was issued and is finalized prior to expiration, per § 18.120.060; these rules also apply when districts are later changed, per § 18.120.070 .

See related topics for how current zoning, land use, development standards, parking, design review, and overlay districts interact with any proposed changes to a nonconforming site. This page does not cover the California Building Standards Code.

Decision-critical rules (at a glance)

Airport-approach overlay nonconformities (special case)

Within mapped airport approach/transition/horizontal/conical zones, nonconforming structures, trees, and uses have special rules:

• Existing nonconforming structures/trees/uses are not forced down/removed and can continue, but alterations typically require a planning commission permit and cannot increase hazard to air navigation, per § 18.132.110 and § 18.132.130; similar provisions apply to Adin (§ 18.134.070, § 18.134.090) and Spalding Tract (§ 18.136.070, § 18.136.090) .
• Variances may be available (case-by-case) where strict application causes hardship, per § 18.132.140, § 18.134.100, § 18.136.100; coordinate with the County before assuming relief is possible .
• Use restrictions prohibit glare, radio interference, and other aviation hazards in these overlay zones (e.g., § 18.132.100, § 18.134.060, § 18.136.060) .

When these overlays apply, confirm mapped boundaries and height baselines (e.g., official airport elevations and zone maps) before planning any changes, and consider the Overlay Districts and Variances and Exceptions pages for process context.

District-by-district context in unincorporated Lassen County

Nonconforming rules apply across districts; knowing each district’s purpose and typical standards helps you evaluate whether to seek an expansion, to rebuild, or to convert to a conforming use.

C-L Local Commercial (Chapter 18.30)

• Purpose/where it applies: Neighborhood-serving commercial areas.
• Typical permitted uses: Local retail and services; all development subject to design review; off-street parking per Chapter 18.104; screening/landscaping standards apply per § 18.30.060 . See Design Review, Parking, and Landscaping and Screening.
• Key dimensional standards: Front yard generally none except ≥50 ft from roadway centerline; side/rear 15 ft (or 25 ft when adjacent to R zones); max height 2 stories/35 ft (Chapter 18.30 development standards; Not found in retrieved materials for the specific § number) .

C-G General Commercial (Chapter 18.32)

• Purpose: Regional-scale, urbanized commercial areas per § 18.32.010 .
• Typical permitted uses: Wide range—retail shops, offices, bakeries, nurseries, shopping centers, auto sales; some uses by permit (e.g., motels/hotels, theaters, private recreation), per §§ 18.32.030–.040 .
• Key dimensional standards: Not found in retrieved materials.

B-P Business Park (Chapter 18.39)

• Purpose: Light industrial/office parks with minimal external impacts, per § 18.39.010 .
• Typical permitted uses: Offices, labs, R&D, warehousing, light manufacturing/assembly, indoor sports, day care; similar uses as determined by the Planning Director, per § 18.39.030 .
• Key dimensional standards: Not found in retrieved materials.

H Highway Service/Commercial (Chapter 18.92)

• Purpose/where it applies: Highway-oriented commercial nodes.
• Typical permitted/conditional uses: Motels, RV parks/campgrounds, auto service stations (conditions), restaurants, real estate offices per H-district use lists (Chapter 18.92; specific §s not fully retrieved) .
• Key dimensional standards: Max height 35 ft (2.5 stories); front yard 30 ft (for dwellings/hotels/motels; plus any adopted building line); side/rear “same as R-1,” per § 18.92.050; all development is subject to design review per § 18.92.060 .

M-R Mountain Resort (Chapter 18.55)

• Purpose: Four-season resort-oriented areas with unique resources, per § 18.55.010 .
• Typical permitted uses: Lodging (inns/hotels/cabins), multifamily/single-family including timeshares, mixed-use buildings, retail/food service (brew pub/winery), offices, limited industrial (e.g., laundry/storage/woodworking), fueling stations, RV parks/campgrounds, and more per § 18.55.030 .
• Key dimensional standards: Not found in retrieved materials.

R-S Recreation/Service (Chapter 18.54)

• Purpose/where it applies: Recreation-service areas supporting resort and visitor uses.
• Typical permitted uses: Small retail, convenience stores, bars/taverns/restaurants, curio shops, dancehalls per R-S use lists; additional uses by permit (e.g., service stations, marine repair, RV parks/campgrounds, recreation facilities, residence with business) per § 18.54.040 .
• Key dimensional standards: Not found in retrieved materials.

NH Natural Habitat Combining Overlay (Chapter 18.94)

• Purpose: Protect mapped wildlife habitat areas in the General Plan/area plans per § 18.94.010 .
• How it applies: Adds to underlying zone; projects must honor average building site area and density controls; NH figure appended to the zone controls density per §§ 18.94.020–.030 .
• Key dimensional standards: Density not to exceed average parcel size allowed by the base district/plan per § 18.94.030 .

C-2 Old Commercial District (Chapter 18.38)

• Purpose/where it applies: Legacy district—applies only to land zoned C-2 before this Title took effect; no new rezonings to C-2 after that date per § 18.38.010 context (excerpt states applicability) .
• Process notes: Development subject to design review per § 18.38.100; certain parking landscaping rules apply per § 18.38.110 .
• Key dimensional standards: Not found in retrieved materials.

Airport Approach Overlays—Susanville/Westwood/Herlong (Chapter 18.132)

• Purpose: Protect airport airspace and public safety; establishes height limits by zone and airport elevations per § 18.132.060 and related map/file provisions §§ 18.132.040–.050; use restrictions prohibit glare/interference per § 18.132.100; nonconforming allowances and permits per §§ 18.132.110, 18.132.130; variances per § 18.132.140 .

Airport Approach Overlay—Adin Airport (Chapter 18.134)

• Purpose/limits: Similar protections; nonconformity continuance and alteration permits per §§ 18.134.070, 18.134.090; variances per § 18.134.100; use restrictions per § 18.134.060 .

Airport Approach Overlay—Spalding Tract Airport (Chapter 18.136)

• Purpose/limits: Similar protections; nonconformity continuance and alteration permits per §§ 18.136.070, 18.136.090; administrative process and height limits outlined in Chapter 18.136 .

Practical notes for projects affecting nonconformities

• Coordinate early with Planning on whether the existing use is “lawful” and nonconforming under § 18.120.010–.020; this affects whether a discretionary approval is even required for continuation .
• Time is critical after damage or a shutdown. Missing the one-year application deadline after damage or the one-year inactivity window risks losing nonconforming status under §§ 18.120.030–.040 .
• If you’re near an airport overlay, your ability to alter or replace a nonconforming structure/tree is further constrained; you’ll likely need a planning commission permit under § 18.132.130, § 18.134.090, or § 18.136.090 and cannot increase hazard to air navigation .
• Design changes to bring a site into compliance may also trigger design review and updated signage or site parking requirements if you pivot to a conforming use.

Checklist

• Confirm the use/structure was lawfully established before the zoning change (property records, permits).
• Identify the current base district and any overlays via Lassen County Zoning and Overlay Districts.
• Determine if the proposal is maintenance (≤25% assessed value/year) or an expansion/alteration per § 18.120.050 .
• If expanding/altering, prepare for a certificate of conditional use (residential) or a use permit (nonresidential) per § 18.120.050(1) and § 18.120.030 (if rebuilding) .
• If rebuilding after damage >75%, file within 1 year per § 18.120.030; no extensions allowed .
• If operations ceased, assess the one-year abandonment risk; assemble evidence to rebut if needed; note appeal rights under § 18.120.040(b) and § 18.120.080 .
• If in an airport overlay, obtain any required planning commission permit; avoid increasing air navigation hazards per §§ 18.132.110–.130, 18.134.070–.090, 18.136.070–.090 .
• If pivoting to a conforming use, confirm applicable development standards, parking, and design review triggers.

Risks & Ambiguities

Plain-English Summary

If your property in unincorporated Lassen County has a use or building that predates today’s zoning, you can usually keep using it as-is. But if you stop using it for a year, try to expand it, or it’s badly damaged, plan on getting County approvals or bringing it into full compliance—and added rules apply if you’re near an airport overlay.

Source References

• Chapter 18.120 Nonconforming Uses: §§ 18.120.010–.070, .080 (continuation, expansion, damage/abandonment, applicability, appeals)
• Airport Overlays: Chapter 18.132 (Susanville/Westwood/Herlong): §§ 18.132.040–.060, .100–.140; Chapter 18.134 (Adin): §§ 18.134.060–.100; Chapter 18.136 (Spalding): §§ 18.136.060–.100
• Districts/Overlays cited: C-L (Ch. 18.30) special provisions including design review, parking, landscaping/screening; C-G (Ch. 18.32) intent and uses; B-P (Ch. 18.39) intent/uses; H (Ch. 18.92) development standards/design review; M-R (Ch. 18.55) purpose/uses; R-S (Ch. 18.54) uses; NH (Ch. 18.94) intent/standards; C-2 (Ch. 18.38) applicability/design review/parking landscaping

Retrieved passages

• Lassen County Zoning Code (§ 48) High relevance show source text
• Lassen County Zoning Code (§ 2) High relevance show source text
• Lassen County Zoning Code (title for) High relevance show source text
• Lassen County Zoning Code (title to) High relevance show source text
• Lassen County Zoning Code (§ 47) High relevance show source text
• Lassen County Zoning Code (§ 69) High relevance show source text
• CBC § 66321 (§ 66321) High relevance show source text
• Lassen County Zoning Code (§ 37) High relevance show source text

Cited sections

• Chapter 18.120 Nonconforming Uses: **§§ 18.120.010–.070, .080** (continuation, expansion, damage/abandonment, applicability, appeals) (Chapter 18.120)
• Airport Overlays: **Chapter 18.132** (Susanville/Westwood/Herlong): **§§ 18.132.040–.060, .100–.140**; **Chapter 18.134** (Adin): **§§ 18.134.060–.100**; **Chapter 18.136** (Spalding): **§§ 18.136.060–.100** (Chapter 18.132)
• Districts/Overlays cited: **C-L (Ch. 18.30)** special provisions including design review, parking, landscaping/screening; **C-G (Ch. 18.32)** intent and uses; **B-P (Ch. 18.39)** intent/uses; **H (Ch. 18.92)** development standards/design review; **M-R (Ch. 18.55)** purpose/uses; **R-S (Ch. 18.54)** uses; **NH (Ch. 18.94)** intent/standards; **C-2 (Ch. 18.38)** applicability/design review/parking landscaping
• LassenCounty_ZoningCode.md
• 2025 California ADU handbook.md

• Official Lassen County code library