San Diego County — Nonconforming Uses

Last reviewed: July 6, 2026

Overview

This page explains how San Diego County treats nonconforming uses, structures, and lots in the unincorporated areas under the County’s zoning and related ordinances. The County’s Zoning Ordinance is Ordinance No. 1402 (New Series), referenced throughout other County codes as “The Zoning Ordinance” and applied only in the unincorporated areas, not in incorporated cities (§ 84.201(j) ). Where the Zoning Ordinance sets the baseline, other County regulations (e.g., specific plan street setbacks, grading, watercourses, and subdivision rules) affect how existing nonconforming conditions are handled.

Plain-English anchor: A nonconforming condition is something that was legal when established, but no longer matches today’s rules. In the unincorporated areas, the County generally regulates these conditions through its Zoning Ordinance and cross-references in its street setback, grading, watercourse, and subdivision titles.

What the County Code explicitly covers today

• The Zoning Ordinance is identified and cross-referenced as the controlling land-use regulation for unincorporated areas (§ 84.201(j) ).
• Existing buildings that later sit within a newly adopted specific plan street corridor are not required to be removed solely because they became nonconforming to that specific plan; however, further encroachment is prohibited (§ 84.205 ).
• Lawfully nonconforming refuse disposal areas/sanitary fills can be exempt from grading permits if they meet strict conditions, acknowledging their lawful nonconforming status (§ 87.202(c) ).
• Watercourse and floodplain regulation ties directly to Zoning Ordinance “Flood Plain” or “Flood Channel” designators; new or “substantial improvements” in such areas must meet elevation or floodproofing criteria (§ 87.602(d) ).
• Parcel “nonconformity” to minimum lot size is addressed via a merger process for contiguous substandard lots held in common ownership, with conditions and exceptions (§ 81.106 ).

These sections are where the County’s adopted code speaks most clearly to how existing, otherwise lawful conditions interface with today’s standards.

How nonconformity intersects with key County regulations

Specific Plan Street Setback Areas

• Purpose: Keep buildings out of mapped future road corridors, and ensure compatible setbacks along “specific plan streets.” The “Specific Plan Street Setback Ordinance” applies in the unincorporated areas (§ 84.200–§ 84.203 ).
• Key nonconforming rule: Adoption of a specific plan does not, by itself, force removal of a building that becomes nonconforming to the new corridor. But increasing an encroachment is unlawful (§ 84.205 ).
• Where it applies: Properties adjacent to mapped “specific plan streets,” as defined by specific plan centerlines and limits (§ 84.201(b), (d)–(i) ).
• Practical tie-ins: If a remodel or addition would push a building further into a mapped setback, it will be disallowed; consider alternatives through design review or variances and exceptions if applicable.

Floodplain and Flood Channel Designators (Zoning tie-in)

• Purpose: Protect life/property in flood-prone areas; the watercourse chapter enforces restrictions where the Zoning Ordinance has applied Flood Plain or Flood Channel designators (§ 87.602(d) ).
• Key standard: New or “substantial improvements” to structures in floodplains must elevate the lowest floor to or above the 100‑year flood elevation or be floodproofed; the code defines “substantial improvements” for administration (§ 87.602(d) ).
• Where it applies: Unincorporated parcels with Zoning Ordinance Flood Plain/Channel designators; verify designators on your parcel via San Diego County Zoning.
• Practical tie-ins: If your existing structure in a mapped flood area is “substantially improved,” today’s floodproofing/elevation standards will likely apply. Coordinate early with the County and check development standards.

Open Space Easements and Similar Restrictions

• Purpose: Enforce conservation easements and development-restrictive easements granted to the County.
• Key rule: It is unlawful to maintain structures, grading, or clearing contrary to an open space or similar easement’s terms; “nonconforming by easement” is not protected if it violates those terms (§ 87.112 ).
• Where it applies: Any unincorporated parcel subject to an open space/conservation/development-restrictive easement recorded for the County.

Grading Permit Exemptions that Acknowledge Lawful Nonconforming Operations

• Purpose: Identify limited activities exempt from grading permits.
• Key standard: Refuse disposal areas or sanitary fills may proceed without a grading permit if either permitted by the Zoning Ordinance or operating as a lawful nonconforming use and if drainage/lateral support/safety are preserved (§ 87.202(c) ).
• Where it applies: Sites in the unincorporated areas with documented lawful status; confirm underlying approvals with Planning & Development Services.

Lot Merger as a Remedy for Substandard (Nonconforming) Parcels

• Purpose: Allow the County to merge contiguous, commonly-owned parcels where at least one does not conform to current minimum parcel size standards under the Zoning Ordinance, subject to criteria (§ 81.106(a)–(b) ).
• Key conditions: Includes, for example, parcels under 5,000 sq ft, lacking legal access, not meeting sewage/water standards, or inconsistent with the General Plan (outside minimum lot size/density) (§ 81.106(a)(2) ).
• Where it applies: Unincorporated parcels under common ownership; exemptions mirror Government Code allowances (§ 81.106(b) ).

Decision-Relevant Rules and Where They Live

Use this table to triage common nonconformity scenarios in the unincorporated areas.

District-by-District (Overlay) Guide — Where nonconformity matters most

Specific Plan Street Setback Areas

• Purpose: Reserve future right-of-way and keep buildings at compliant setbacks.
• Typical permitted uses: Any use allowed by base zoning outside the mapped setback; within the specific plan area/setback, encroachments are constrained.
• Key dimensional standards: Defined by specific plan lines/centerlines; encroachment rules prohibit increasing nonconforming intrusions (§ 84.201–§ 84.205 ).
• Applies where: A specific plan street is adopted; confirm via San Diego County Land Use and County maps.

Floodplain/Flood Channel Designators

• Purpose: Manage flood risk and regulate development intensity and elevation.
• Typical permitted uses: Uses allowed by base zoning, but new or “substantial improvements” must meet flood elevation/floodproofing standards (§ 87.602(d) ).
• Key dimensional/technical standards: Elevation to or above 100‑year flood or floodproofing; “substantial improvements” threshold governs when standards apply (§ 87.602(d) ).
• Applies where: The Zoning Ordinance has placed Flood Plain/Channel designators; verify via overlay districts.

Open Space/Conservation Easement Areas

• Purpose: Protect conserved resources and restrict incompatible development.
• Typical permitted uses: Only activities consistent with easement terms; contrary structures or grading are unlawful (§ 87.112 ).
• Key standards: Maintain compliance with recorded easement terms; “nonconforming by easement” is not a protected status if it violates the easement.
• Applies where: A recorded easement grants restrictions to the County; consult historic preservation if resources are implicated.

Practical guidance for applicants

• Confirm legal status: Before proposing changes, confirm whether your use/structure/lot was lawfully established and what rules applied at that time. Then check today’s zoning, development standards, parking, and any overlay districts.
• Look for corridor/easement constraints: If you sit within a specific plan street setback, you generally cannot increase encroachment (§ 84.205 ). If you have an open space easement, you cannot maintain work contrary to its terms (§ 87.112 ).
• Floodplain triggers: “Substantial improvements” to existing buildings in flood areas can require elevation or floodproofing (§ 87.602(d) ). Plan scope accordingly.
• Substandard lots: Parcel mergers can cure certain lot-size nonconformities when statutory criteria are met (§ 81.106 ).
• ADU wrinkle: State ADU law limits conditioning approval on fixing existing zoning nonconformities unless there’s a health/safety threat affected by the ADU; this is state law, not local, but it can impact projects on nonconforming lots in the unincorporated areas (Gov. Code, §§ 66322–66323; ). See California ADU law.

Checklist

• Verify parcel is in the unincorporated area and identify your base zone and any designators/overlays via San Diego County Zoning.
• Document that the use/structure/lot was lawfully established at the time it began.
• Check if a specific plan street setback affects your site; if so, confirm no increase in encroachment (§ 84.205 ).
• Determine whether a Flood Plain/Channel designator applies; if so, assess whether your proposal is a “substantial improvement” (§ 87.602(d) ).
• If the lot is substandard, evaluate whether a parcel merger path exists (§ 81.106 ).
• If you operate a refuse disposal/sanitary fill site, confirm if lawful nonconforming status and conditions qualify you for a grading permit exemption (§ 87.202(c) ).
• If any easements encumber the site, verify that all activity conforms to the easement terms (§ 87.112 ).
• Where uncertainty remains, engage County Planning & Development Services; consider variances and exceptions if appropriate.

Risks & Ambiguities

Information Gaps

• County-wide rules on continuation, enlargement, repair, relocation, or termination (“abandonment”) of nonconforming uses and structures: Not found in retrieved materials. Verify with the jurisdiction.
• District-by-district base zone standards and how nonconforming uses are treated in each base zone: Not found in retrieved materials. Verify with the jurisdiction.
• Procedures for proof of legal nonconforming status (e.g., administrative determinations) in the unincorporated areas: Not found in retrieved materials.

Plain-English Summary

If your property in the unincorporated areas has something that was legal when built but no longer fits today’s rules, the County may let it remain, but expansions can be limited—especially in mapped street corridors, flood areas, or where easements apply. Some long-standing operations (like older refuse disposal areas) may have narrow grading-permit exemptions, and substandard lots sometimes must merge with a neighbor to move forward. Get your current zoning/overlays, confirm what was legal when built, and then plan any changes so you don’t trigger stricter requirements or violate setbacks, flood, or easement rules.

Source References

• Specific Plan Street Setback Ordinance: § 84.200–§ 84.205 (The Zoning Ordinance reference and setback rules)
• Definition of “The Zoning Ordinance” as Ordinance No. 1402 (New Series): § 84.201(j)
• Grading permit exemptions acknowledging lawful nonconforming refuse/sanitary fills: § 87.202(c)
• Watercourses/floodplain standards and “substantial improvements” in flood-designated areas: § 87.602(d)
• Merger of contiguous parcels where a parcel does not conform to minimum size (lot nonconformity remedy): § 81.106
• Open space/conservation easements—unlawful to maintain contrary work: § 87.112
• State ADU Law constraints on conditioning approvals to fix zoning nonconformities: Gov. Code §§ 66322–66323 (2025 HCD ADU Handbook)

Retrieved passages

• CFC § 66451.11 (section 66451.11) Medium relevance show source text
• San Diego County Zoning Code (Section 7374) Medium relevance show source text
• San Diego County Zoning Code Medium relevance show source text
• San Diego County Zoning Code (§ 12.101) Medium relevance show source text
• San Diego County Zoning Code (§ 66314) Medium relevance show source text
• San Diego County Zoning Code (§ 66333) Medium relevance show source text
• San Diego County Zoning Code (Section has) Medium relevance show source text
• San Diego County Zoning Code (Section 84.210) Medium relevance show source text
• CBC § 202 (section 202) Medium relevance show source text
• San Diego County Zoning Code (Article 5) Medium relevance show source text

Cited sections

• Specific Plan Street Setback Ordinance: § 84.200–§ 84.205 (The Zoning Ordinance reference and setback rules) (§ 84.200)
• Definition of “The Zoning Ordinance” as Ordinance No. 1402 (New Series): § 84.201(j) (§ 84.201)
• Grading permit exemptions acknowledging lawful nonconforming refuse/sanitary fills: § 87.202(c) (§ 87.202)
• Watercourses/floodplain standards and “substantial improvements” in flood-designated areas: § 87.602(d) (§ 87.602)
• Merger of contiguous parcels where a parcel does not conform to minimum size (lot nonconformity remedy): § 81.106 (§ 81.106)
• Open space/conservation easements—unlawful to maintain contrary work: § 87.112 (§ 87.112)
• State ADU Law constraints on conditioning approvals to fix zoning nonconformities: Gov. Code §§ 66322–66323 (2025 HCD ADU Handbook) (§ 66322)
• SanDiegoCounty_ZoningCode.md
• 2025 California ADU handbook.md

• Official San Diego County code library