Contra Costa County — Nonconforming Uses

Overview

In unincorporated areas of Contra Costa County, nonconforming uses are governed by Divisions 82 and 84 of the County’s zoning ordinance. A “nonconforming use” is defined by the ordinance and treated through a few targeted provisions, including special rules in airport-hazard areas and for certain regulated uses. Whether something is nonconforming always turns on what Divisions 82 and 84 allow today in the applicable zoning district and overlay.

In unincorporated Contra Costa County, a “nonconforming use” is any use of land, a building, or a structure that does not conform to Divisions 82 and 84 for the district in which it is located (§ 82-4.280).

What the County Code Actually Says About Nonconforming Uses

• Definition and scope

  • A nonconforming use is a use of land, building, or structure that does not conform to the current zoning rules in Divisions 82 and 84 for the district where it sits (§ 82-4.280).
  • Divisions 82 and 84 regulate all private/public uses of land in the unincorporated areas (§ 82-2.004), and are applied as minimum requirements, liberally construed in favor of the County (§ 82-28.610). General compliance is mandatory; violations are infractions (§ 82-28.606).

• Airport hazard regulations (nonconforming structures/trees and uses within that chapter)

  • Structures or trees that did not conform as of February 9, 1956, may continue; the chapter does not require their removal or alteration (§ 86-4.018).
  • Construction or alteration begun before February 9, 1956, may proceed if diligently prosecuted and completed within two years (§ 86-4.018).
  • Replacing, substantially altering, repairing, rebuilding, allowing to grow higher, or replanting a nonconforming structure or tree requires a permit from the Board of Adjustment; no permit may increase the height or hazard to air navigation (§ 86-4.018). Routine maintenance that does not enlarge/increase height does not require a permit (§ 86-4.018).

• Accessory dwelling units on lots with a nonconforming primary dwelling

  • If the existing primary dwelling unit is a legal nonconforming unit, an ADU or JADU may be constructed only if the nonconformity is not expanded and the ADU/JADU meets all current applicable zoning and building standards (§ 82-24.018). See County ADU law and the California Building Standards Code for related state requirements.

• Firearms sales: legacy nonconforming uses

  • Persons asserting a legal nonconforming firearms sales use as of December 28, 1995, were required to submit written evidence of the extent/scope of that use within 90 days and obtain a County firearms dealer license (§ 82-36.204).
  • Any such legal nonconforming firearms sales use may not be increased, enlarged, or expanded without a land use permit; all applicable state/federal permits must be maintained (§ 82-36.204).

• Zoning districts and applicability

  • All land-use districts in unincorporated areas are established in Division 84 and shown on the official Zoning Map (§ 84-2.004, § 84-2.002). Whether a use is nonconforming depends on the allowed uses in the current district and any combining/overlay district. See Contra Costa County Zoning and Overlay Districts.

Countywide Decision Points (Nonconforming Uses)

How Overlays Interact with Nonconforming Status

• The County’s combining districts can change what the “underlying district” allows today, which in turn affects whether a use is considered nonconforming. For example:
  • The -CE Cannabis Exclusion combining district applies in specified communities and governs over any conflicting underlying district rules (§ 84-86.204, § 84-86.206). All uses otherwise allowed by the underlying district remain permitted except as limited by the -CE chapter (§ 84-86.210).
  • The -SG Solar Generating combining district allows all uses permitted in the underlying district and adds a path for commercial solar facilities via land use permit per Chapter 88-30 (§ 84-88.402, § 84-88.404).
• For any overlay area, if today’s overlay modifies what’s allowed, a previously established use might become a nonconforming use relative to the combined standards. Verify the current map and overlay status with Contra Costa County Zoning and Overlay Districts.

District-by-District/Overlay Breakdowns Relevant to Nonconforming Uses

Airport-Hazard Regulations Area (Chapter 86-4)

• Purpose: Manage structures/trees and uses to avoid creating an “airport hazard to air navigation” (term used in § 86-4.018).
• Typical permitted uses: Not found in source materials.
• Key dimensional standards: Not found in source materials; however, nonconforming structures/trees as of February 9, 1956 can continue; substantial changes need a Board of Adjustment permit and cannot increase height or hazard (§ 86-4.018).
• Where it applies: Not found in source materials. Verify with the jurisdiction.

-CE Cannabis Exclusion Combining District (Chapter 84-86)

• Purpose: Exclude commercial cannabis activities in listed unincorporated communities (Acalanes Ridge, Alamo, Bethel Island, Blackhawk, Bollinger Canyon, Contra Costa Centre, Knightsen, Sandmound Slough, Saranap) (§ 84-86.204, § 84-86.208).
• Typical permitted uses: All uses otherwise allowed in the underlying zoning district (§ 84-86.210).
• Key dimensional standards: Governed by the underlying district; if conflicts arise, -CE governs (§ 84-86.206).
• Where it applies: The communities listed in § 84-86.204.

-SG Solar Generating Combining District (Chapter 84-88)

• Purpose: Provide for solar energy development while retaining underlying district permissions.
• Typical permitted uses: All uses allowed in the underlying zoning district remain permitted (§ 84-88.402).
• Key dimensional standards: Governed by the underlying district; commercial solar facilities require a land use permit under Chapter 88-30 (§ 84-88.404).
• Where it applies: Not found in source materials. Verify with the jurisdiction.

Working With Nonconforming Uses: Practical Guidance

• Start with the map: The County’s Zoning Map adopted at § 84-2.002 and the districts at § 84-2.004 establish today’s allowed uses; your use is nonconforming if it no longer fits the district+overlay allowances.
• Airport-hazard areas: If your site is in an airport-hazard regulatory area, expect heightened scrutiny; any replacement or substantial alteration of a nonconforming structure/tree needs a Board of Adjustment permit and cannot increase height/hazard (§ 86-4.018).
• ADU on a lot with a nonconforming primary dwelling: You can add an ADU/JADU only if you do not expand the existing nonconformity and the new unit fully meets current standards (§ 82-24.018). This can trigger updated parking, development standards, and possibly design review depending on the project.
• Use-specific legacy rights: Firearms sales nonconforming uses are explicitly regulated—no enlargement without a land use permit, with licensing and permits required (§ 82-36.204).
• Enforcement: The County treats ordinance provisions as minimums and enforces violations as infractions (§ 82-28.606, § 82-28.610). If a proposal would increase a nonconformity, expect to seek relief, if available, under Variances and Exceptions (not addressed in the source materials for nonconforming uses—verify with the jurisdiction).

Checklist

• Confirm the property is in the unincorporated area (§ 82-2.004).
• Identify the current base district and any combining/overlay districts using the official Zoning Map (§ 84-2.002, § 84-2.004).
• Determine whether the existing use conforms to current district+overlay allowances; if not, it is a “nonconforming use” (§ 82-4.280).
• If in an airport-hazard area, determine whether any structure/tree is nonconforming and whether proposed work is “maintenance” (no permit) or “replacement/substantial alteration” (Board of Adjustment permit required; no height/hazard increase) (§ 86-4.018).
• For sites with a nonconforming primary dwelling, design any ADU/JADU so it does not expand the nonconformity and meets today’s zoning/building standards (§ 82-24.018).
• For legacy firearms sales sites, ensure County firearms dealer licensing is current and obtain a land use permit before any enlargement/expansion (§ 82-36.204).
• Verify any needed design review, parking, and development standards triggered by the proposed change (as applicable—verify with the jurisdiction).
• Document the existing condition and any evidence supporting legacy status; where the code is silent, “Verify with the jurisdiction.”

Risks & Ambiguities

Plain-English Summary

In unincorporated Contra Costa County, a nonconforming use is a use that no longer matches what the zoning rules currently allow in that district. The code provides targeted rules: airport-hazard areas strictly limit changes to legacy nonconforming structures/trees; ADUs on lots with a nonconforming primary dwelling can be added only if they do not expand the nonconformity and meet today’s standards; and legacy firearms sales uses cannot expand without a land use permit. Everything else must comply with current district and overlay rules.

Source References

• § 82-2.004 (Application of Divisions 82 and 84 to unincorporated areas)
• § 82-2.002 (Adoption of Divisions 82 and 84)
• § 82-4.280 (Definition of “nonconforming use”)
• § 82-28.606 (Compliance and enforcement)
• § 82-28.610 (Interpretation—minimum requirements; liberal construction)
• § 84-2.004 (Districts established)
• § 84-2.002 (Zoning map adopted)
• § 86-4.018 (Nonconforming uses—airport hazard chapter)
• § 82-24.018 (ADUs/JADUs with a nonconforming primary unit)
• § 82-36.204 (Nonconforming firearms sales uses)
• § 84-86.204, § 84-86.206, § 84-86.210 (Cannabis Exclusion -CE combining district)
• § 84-88.402, § 84-88.404 (-SG Solar Generating combining district)

Source passages

• Contra Costa County Zoning Code (§ 82-4.280) Medium relevance show source text
• Contra Costa County Zoning Code (§ 82-28.606) Medium relevance show source text
• Contra Costa County Zoning Code (§ 86-4.018) Medium relevance show source text
• Contra Costa County Zoning Code (§ 84-2.004) Medium relevance show source text
• Contra Costa County Zoning Code (§ 82-2.004) Medium relevance show source text
• Contra Costa County Zoning Code (§ 82-2.002) Medium relevance show source text
• Contra Costa County Zoning Code (§ 82-28.610) Medium relevance show source text
• Contra Costa County Zoning Code (§ 82-24.018) Medium relevance show source text
• Contra Costa County Zoning Code (§ 84-88.402) Medium relevance show source text
• Contra Costa County Zoning Code (§ 82-36.204) Medium relevance show source text
• Contra Costa County Zoning Code (§ 84-2.002) Medium relevance show source text
• Contra Costa County Zoning Code (§ 84-86.204) Medium relevance show source text

Cited sections

• § 82-2.004 (Application of Divisions 82 and 84 to unincorporated areas) (§ 82-2.004)
• § 82-2.002 (Adoption of Divisions 82 and 84) (§ 82-2.002)
• § 82-4.280 (Definition of “nonconforming use”) (§ 82-4.280)
• § 82-28.606 (Compliance and enforcement) (§ 82-28.606)
• § 82-28.610 (Interpretation—minimum requirements; liberal construction) (§ 82-28.610)
• § 84-2.004 (Districts established) (§ 84-2.004)
• § 84-2.002 (Zoning map adopted) (§ 84-2.002)
• § 86-4.018 (Nonconforming uses—airport hazard chapter) (§ 86-4.018)
• § 82-24.018 (ADUs/JADUs with a nonconforming primary unit) (§ 82-24.018)
• § 82-36.204 (Nonconforming firearms sales uses) (§ 82-36.204)
• § 84-86.204, § 84-86.206, § 84-86.210 (Cannabis Exclusion -CE combining district) (§ 84-86.204)
• § 84-88.402, § 84-88.404 (-SG Solar Generating combining district) (§ 84-88.402)

• Official Contra Costa County code library