Costa Mesa — Nonconforming Uses

Last reviewed: July 1, 2026

Overview

This page explains how the City of Costa Mesa treats nonconforming uses, nonconforming structures, and nonconforming lots under the municipal zoning code (Title 13, Chapter X). It synthesizes the code's definitions and the practical limits on continuing, altering, rebuilding or changing nonconforming conditions so property owners and analysts know what is allowed, what triggers loss of the nonconforming status, and which standards will control any restoration or change. For background on applicable districts and standards see Costa Mesa Zoning and the city's Development Standards pages linked below.

What the ordinance covers (short list)

• Legal definition and scope of nonconforming use, nonconforming development, nonconforming lot, and nonconforming dwelling unit — § 13-202 .
• Maintenance/repair rights and limits when a nonconforming development is declared unsafe — § 13-203 .
• Continuance, change, enlargement, abandonment, and replacement rules (the code's Table 13‑204) — § 13-204 .
• Special rebuilding rules for multi‑family residential zones (including R2‑MD, R2‑HD, R3, PDR categories) — § 13-205 .

Key rules (plain-English synthesis, with the controlling §)

• A nonconforming use is an existing, legally established use that is no longer permitted in the zone where it sits. The code's definitions are in § 13-202.

• Continuation: A legally nonconforming use may generally continue in its present location (the city expressly allows continuance in many instances), subject to limits on expansion or relocation. See § 13-204 and Table 13‑204.

• Abandonment / discontinuance: For nonresidential structures/uses, if the nonconforming use is discontinued or abandoned for 6 consecutive months or for 18 nonconsecutive months during any three‑year period, it may not be reestablished and any future use must conform to the zoning code; the code does not require proof of intent to abandon — see § 13-204.

• Enlargement and relocation: A nonconforming use cannot be enlarged, increased, or moved to another part of the lot beyond the area it occupied when it became nonconforming (Table 13‑204 / § 13‑204).

• Structural alterations: Generally, developments devoted to nonconforming uses shall not be structurally altered except to change the use to a conforming use. Limited structural alterations that do not extend the life of the nonconforming use may be approved by the development services director if the alteration conforms to the Code — see § 13‑204.

• Maintenance & repair: Ordinary maintenance and strengthening to make structures safe is allowed, but if an official declares a nonconforming development unsafe due to lack of maintenance, it shall not be restored except in conformity with the district regulations — § 13‑203.

• Destruction / reconstruction: For commercial/industrial/institutional nonconforming developments, if unintentional destruction exceeds 50 percent of market value, reconstruction is limited — see the rebuilding rules in Table 13‑204 and § 13‑204; reconstruction must not increase the nonconformity and must comply with other Code standards (setbacks, lot coverage, height, parking, landscaping, etc.).

• Multi‑family voluntary demolition: In the R2‑MD, R2‑HD, R3, and PDR zones, voluntarily demolished units may be rebuilt only as an equal or lesser number of units and must meet applicable development standards; rebuilding is limited by the General Plan rebuilding incentive and the number of legal nonconforming units (see § 13‑205).

• Change to another nonconforming use: The code allows change to another nonconforming use only if the development services director finds the proposed use is equally or more appropriate for the district; conditions and reasonable alterations may be required — § 13‑204.

District-by-district breakdown (practical focus for nonconforming issues)

Note: below we name the actual Costa Mesa districts and summarize how the nonconforming provisions interact with those districts. Where the ordinance specifies district development standards, I cite that table; where the ordinance text does not set a particular numeric standard for nonconforming actions, I note "Not found in retrieved materials" and flag "Verify with the jurisdiction".

Residential zones — R1, R2‑MD, R2‑HD, R3

• Purpose & typical uses: Single‑family for R1; multi‑family/residential types for R2‑MD, R2‑HD, and R3 (see the Land Use Matrix, Table 13‑30) .
• Nonconforming rules that matter: Residential nonconforming dwelling units may be altered or restored provided the zone is residential, the addition complies with the Code, the addition does not eliminate required parking/garage access, and the dwelling is not made more nonconforming; minor encroachments into setbacks are allowed by minor modification in some cases — § 13‑204 (Table 13‑204) and § 13‑205 for multi‑family rebuilding.
• Key dimensional standards to check (where nonconforming rebuild/repair must comply): Front setback: 20 ft (R1/R2/R3); Side interior: 5 ft (exceptions for small accessory structures); Rear: 10–20 ft depending on story and zone) — see Residential Development Standards Table 13‑32. If you plan to rebuild you must meet these or the reconstruction must not increase nonconformity — § 13‑204.

Planned Development Residential — PDR‑LD, PDR‑MD, PDR‑HD, PDR‑NCM

• Purpose & typical uses: Planned residential development with varying density and design requirements; many multi‑family conversions and master plans fall here (see Table 13‑30) .
• Nonconforming rules: Same Chapter X nonconforming provisions apply; the master plan process can be used to seek rebuilding exceptions for existing nonconforming projects under § 13‑205 (multi‑family) and overlay-specific provisions where authorized. Verify with the applicable specific plan text where a PDR site lies in an overlay.

Commercial & Mixed-use zones — C1, C2, TC, CL, AP, PDC

• Purpose & typical uses: Retail, commercial services, town center and planned commercial developments (see Table 13‑30).
• Nonconforming rules that matter: Nonresidential nonconforming uses in commercial zones may continue unless abandoned; structural alterations that would extend the life of the nonconformity are restricted and require director approval and conformance with Code standards (setbacks, parking, landscaping, etc.). If destroyed more than 50% of market value by unintentional events, reconstruction is limited — § 13‑204.

Industrial & Institutional zones — MG, MP, I&R variants

• Purpose & typical uses: Manufacturing, industrial parks and institutional/recreation uses per Table 13‑30 and development standards like Table 13‑66 for I&R zones.
• Nonconforming rules: Same general nonconforming rules apply; nonresidential developments are tightly limited for structural alteration and rebuilding after destruction (the 50% market value threshold and requirement not to increase nonconformity) — § 13‑204.

Quick decision table (most decision‑relevant items)

How nonconforming rules interact with other review topics

• New or restored projects must meet development standards like setbacks, lot coverage and parking in the zone; see the city's Development Standards and the Residential Development Standards (Table 13‑32) for numeric setbacks and related rules.
• Parking shortfalls tied to nonconforming developments may prevent changes unless additional parking is provided — consult Costa Mesa Parking and § 13‑204 regarding replacement/continuance of uses in a development with deficient parking.
• If proposal requires discretionary relief (variances, changes in use, or master plan deviations) coordinate with Costa Mesa Variances and Exceptions and be prepared for design oversight per Costa Mesa Design Review. Not all nonconforming rebuild exceptions are automatic — Verify with the jurisdiction.

Other relevant internal links you may want early in an application: Costa Mesa Zoning, Costa Mesa Land Use, and Costa Mesa Overlay Districts.

Also note that building condition, structural repairs and compliance with the state code may raise Title 24 questions handled by the building department; for the building code context consult the California Building Standards Code. (This page intentionally does not cover Title 24 permit mechanics.)

Checklist (what an applicant must satisfy to pursue work involving a nonconforming condition)

• Confirm the nonconforming status and the date/use that triggered it (legal establishment documented). Verify with the jurisdiction. § 13‑202
• Determine whether the use has been discontinued/abandoned (check 6 months / 18 nonconsecutive months rules for nonresidential uses). § 13‑204
• If proposing structural alteration or change of use, prepare an application showing the alteration will not extend the life of the nonconforming use or will change the use to a conforming use; include parking calculations. § 13‑204
• If rebuilding after damage, provide market‑value damage estimate and demonstrate whether destruction exceeded 50% — attach appraisal/insurance data. § 13‑204
• Show compliance with applicable district standards (setbacks, lot coverage, height, parking, landscaping) — reference Table 13‑32 (residential) or the zone table for the parcel.
• If proposing change to another nonconforming use, include justification demonstrating why the proposed use is equally or more appropriate to the district for director review. § 13‑204
• If the site lies within an overlay or specific plan area, check the overlay/specific‑plan text and be ready to comply with overlay rebuilding/deviation processes.

Risks & Ambiguities

Plain-English Summary

If your property in Costa Mesa is legally nonconforming, you can usually keep using it as it currently exists, but you cannot enlarge or move the nonconforming use, and long gaps or abandonment (e.g., 6 months continuous for nonresidential uses) can eliminate your right to continue it; if you rebuild after major damage you must meet the Code's rebuilding rules and not make the nonconformity worse — see § 13‑202 through § 13‑205.

Information Gaps

• Specific administrative procedures (forms/fees/timelines) for applying for director approval to alter a nonconforming development — Not found in retrieved materials. Verify with the Development Services Department.
• Precise valuation methodology the city accepts to establish the 50% market‑value threshold after destruction — Not found in retrieved materials. Obtain city guidance early.
• Any city policy documents or guidelines interpreting “extend the life of the nonconforming use” for specific uses (e.g., cannabis storefronts were given special rules elsewhere in the Code) — partial language present; administrative practice is not in the retrieved materials.

Source References

• Costa Mesa Municipal Code, Chapter X, NONCONFORMING USES, DEVELOPMENTS AND LOTS: § 13‑201 (purpose); § 13‑202 (definitions).
• Maintenance and repair rules: § 13‑203.
• Nonconforming provisions and Table 13‑204 (continuance, change, alteration, rebuilding rules): § 13‑204.
• Multi‑family rebuilding after voluntary demolition: § 13‑205.
• Residential development standards (setbacks, driveway, parking prerequisites) — Table 13‑32.
• Land Use Matrix (permitted uses by zone) — Table 13‑30.
• Zone development standards for some industrial/ institutional zones — Table 13‑66.
• Overlay and specific plan interaction notes — table and overlay guidance in the Code (see mixed‑use overlay and specific plan references).

Retrieved passages

• Costa Mesa Zoning Code (Chapter III) High relevance show source text
• Costa Mesa Zoning Code High relevance show source text
• Costa Mesa Zoning Code (Chapter III) High relevance show source text
• Costa Mesa Zoning Code High relevance show source text
• Costa Mesa Zoning Code (§ 2) High relevance show source text
• Costa Mesa Zoning Code (Chapter X) High relevance show source text
• Costa Mesa Zoning Code (§ 2) High relevance show source text
• Costa Mesa Zoning Code (§ 2) High relevance show source text
• CBC § 66314 (§ 66314) Medium relevance show source text
• Costa Mesa Zoning Code Medium relevance show source text
• Costa Mesa Zoning Code (Chapter IX) Medium relevance show source text
• CBC § 66321 (§ 66321) Medium relevance show source text
• Costa Mesa Zoning Code (Article 6) Medium relevance show source text
• Costa Mesa Zoning Code (Chapter VI) Medium relevance show source text

Cited sections

• Costa Mesa Municipal Code, Chapter X, NONCONFORMING USES, DEVELOPMENTS AND LOTS: **§ 13‑201** (purpose); **§ 13‑202** (definitions). (Chapter X)
• Maintenance and repair rules: **§ 13‑203**. (§ 13)
• Nonconforming provisions and Table **13‑204** (continuance, change, alteration, rebuilding rules): **§ 13‑204**. (§ 13)
• Multi‑family rebuilding after voluntary demolition: **§ 13‑205**. (§ 13)
• Residential development standards (setbacks, driveway, parking prerequisites) — Table **13‑32**.
• Land Use Matrix (permitted uses by zone) — Table **13‑30**.
• Zone development standards for some industrial/ institutional zones — Table **13‑66**.
• Overlay and specific plan interaction notes — table and overlay guidance in the Code (see mixed‑use overlay and specific plan references).
• CostaMesa_ZoningCode.md

• Official Costa Mesa code library