Aliso Viejo — Nonconforming Uses

Last reviewed: July 3, 2026

Overview

This reference explains how the City of Aliso Viejo regulates nonconforming uses, nonconforming structures, and nonconforming lots under the local zoning code (AVMC Title 15). The primary rules are in Chapter 15.86 and the code cross‑references development standards, parking, ADU rules, and district tables that determine whether a use/structure may continue, be repaired, or must be brought into conformance. See § 15.86.010–.060 for the chapter framework and § 15.86.020 for the core nonconforming‑use rules.

What the code actually requires (core rules)

• Continuation: A lawful pre‑existing nonconformity may continue, subject to limits in § 15.86.020.
• Maintenance & repair: Ordinary maintenance and repair are allowed; structural alterations are allowed only if they do not increase the degree of nonconformity or create new nonconformities (§ 15.86.020(B)).
• Discontinuance: If a nonconforming use is discontinued for one year, the nonconforming status terminates and any new use must conform to the code (§ 15.86.020(C)).
• Intensification: Nonconforming nonresidential uses cannot be enlarged or intensified; residential nonconforming uses can be intensified only so long as no new or increased setback/height/other nonconformity results (§ 15.86.020(D)).
• Restoration after damage: A nonconforming use or structure may be restored after disaster only if permit submittal and construction timelines are met; nonresidential structures that are damaged to 50% or more of replacement cost (as determined by the Director) must be rebuilt to current standards (§ 15.86.020(E–F)).
• Change of ownership: Ownership/management changes do not terminate nonconforming status so long as use/intensity does not change (§ 15.86.020(G)).
• Nonconforming lots: A legally established nonconforming lot may be used if all code requirements other than lot conformity itself are met (§ 15.86.030).
• Nonconforming parking & signs: Parking and sign nonconformance are handled in separate chapters—see § 15.38.170 (parking) and § 15.34.090 (signs).

To prepare filings you will likely also deal with the City’s development standards, parking, and design review rules (each invoked in other AVMC chapters that interact with nonconformance). See the ADU rules for how accessory units interact with nonconforming zoning (below).

District‑by‑district (how nonconforming issues map to districts)

Below are the City’s primary districts that most commonly raise nonconforming questions. Each subsection gives the district purpose, typical permitted uses (high level), key dimensional standards that matter to nonconformities, and where the district typically applies in the city. District tables and development standards are taken from the zoning code’s development standards tables.

RL (Residential — Low)

• Purpose: Intended for low‑density single‑family residential development.
• Typical permitted uses: single‑family detached homes, accessory structures, and customary residential accessories (guest houses, ADUs subject to ADU rules).
• Key dimensional standards: Front setback 10 ft, Side: 10 ft (one side) or 10 ft aggregate, Rear: 10 ft; building coverage and perimeter setbacks shown in the residential table (see the code table). Minimum front setback and perimeter rules are important when assessing whether an existing building is a nonconforming structure. (See the residential standards table.)
• Where it applies: Typical single‑family neighborhoods in the city; consult the official zoning map for parcel‑level districting.

RM (Residential — Medium)

• Purpose: Medium‑density housing, commonly single‑family attached or low‑rise multifamily.
• Typical permitted uses: Attached single family, small multifamily, accessory uses and permitted ADU configurations.
• Key dimensional standards: Front setback 10 ft, Side: 0 ft on attached side; 10 ft open side, Rear: 10 ft; other multifamily perimeter setbacks and landscaping minimums apply. If a structure predates the code and violates these setbacks, it is a nonconforming structure under Chapter 15.86.

RH / RVH (Residential — Higher density / Very High)

• Purpose: Higher‑density multifamily housing. Typical standards differ from RL/RM; perimeter setbacks and minimum open space standards are larger for multifamily projects.
• Typical permitted uses: Multifamily dwellings, associated amenities.
• Key dimensional standards: See multifamily rows in the residential table (minimum boundary landscaping and setbacks can be 15–20 ft depending on context). Perimeter setbacks increase 1 ft for every ft above 35 ft in height—relevant when calculating if restoration would create a new nonconformity.

PRD (Planned Residential Development)

• Purpose: Project‑specific planned residential developments; standards approved per project.
• Typical permitted uses: As approved in each PRD’s plan (residential and associated amenities).
• Key dimensional standards: Project‑specific; the code notes PRD standards are set for each project and some existing PRDs may use legacy standards—verify whether the PRD in question was approved before or after the current code effective date. That status affects nonconforming treatment.

CT (Town Center Commercial)

• Purpose: Mixed retail/entertainment and pedestrian‑oriented uses in the town center.
• Typical permitted uses: Retail, restaurants, service uses, mixed‑use buildings where permitted. See the CT column in the nonresidential uses table.
• Key dimensional standards: Max height commonly up to 45 ft, FAR up to 1.25; minimum perimeter setbacks vary (arterial: 40 ft; local nonresidential: 20 ft etc.). These standards determine whether an existing building is nonconforming for height or FAR.

CC (Community Commercial), CN (Neighborhood Commercial)

• Purpose: CC for larger community‑serving commercial; CN for small neighborhood retail. Typical uses and the uses table columns show which commercial activities are allowed. Nonconforming retail uses are treated under § 15.86.020 and parking changes must meet § 15.38.170.

PO (Professional Office), BP‑1 / BP‑2 (Business Park 1 & 2)

• Purpose: Office and business park employment centers; BP districts may allow light industrial/research uses.
• Typical permitted uses: Professional offices, R&D, light manufacturing (BP), corporate campuses. If a use pre‑dates a zoning change and is no longer allowed, it is a nonconforming use and the intensification/expansion rules apply.
• Key dimensional standards: Heights and FARs vary—PO FAR 0.6, BP FAR up to 1.5 (district dependent); minimum perimeter setbacks detailed in the nonresidential standards table and subject to height‑based increases.

Notes on permitted uses lists: The code’s land‑use tables (district use matrix) show which uses are permitted outright (A), allowed with a conditional use permit, allowed with a temporary permit (TUP), or prohibited (NP). When a use exists in a district but is no longer listed as permitted, it is a nonconforming use under § 15.86.020 and is subject to those restrictions.

Quick reference table — Decision‑relevant nonconforming standards

Checklist — What an applicant should confirm before filing

• Confirm the historic legal status: Was the use/structure lawfully established before the current AVMC rules? Verify permits/records. § 15.86.020.
• For damaged structures, get a Director‑level replacement‑cost assessment if nonresidential damage may approach 50%. § 15.86.020(F)(3).
• Confirm whether any physical change would increase the degree of nonconformity (setbacks, height, FAR) against the applicable district standards (see the city’s development standards).
• Check parking obligations and whether an existing parking ratio is “grandfathered” or must be upgraded per § 15.38.170 and the parking rules.
• If proposing an ADU on a nonconforming lot or structure, confirm ADU-specific nonconforming provisions in § 15.14.080 and state ADU law; the code states conforming ADUs are not required to correct certain nonconforming zoning conditions. Link to the ADU rules: ADUs.
• If the property is within an overlay or regulated by a Specific Plan (coastal, historic, etc.), check overlay districts — overlays can alter whether something is nonconforming or require additional permits.
• Confirm whether design review or a discretionary permit is required: consult design review.

Risks & Ambiguities

Plain‑English summary (one paragraph)

If your use or building in Aliso Viejo was legal when it was built but no longer meets today’s zoning rules, you usually can keep it — you may repair it and in some cases make limited changes — but you cannot expand the nonconforming part, you must not abandon the use for more than one year, and if a nonresidential building is more than 50% destroyed you generally must rebuild to current code. For ADUs and some residential restorations there are specific provisions; always confirm with the Planning Director and get any required permits within the timelines the code sets (§ 15.86.020–.030).

Source References

• AVMC Chapter 15.86 — Nonconforming Uses, Lots and Structures: § 15.86.010–.060, including § 15.86.020 (continuation/repair/intensification/discontinuance/ restoration) and § 15.86.030 (nonconforming lots).
• AVMC § 15.38.170 — Nonconforming parking (rules on historic parking ratios and expansions).
• AVMC residential development standards table (setbacks, coverage, landscaping) — residential district standards (RL, RM, RH, RVH, PRD). See the residential standards table in the code files.
• AVMC § 15.18.030 — Nonresidential development standards (CT, CC, CN, PO, BP‑1/BP‑2 height, FAR, setbacks).
• AVMC § 15.14.080 — Accessory dwelling units (how ADUs interact with nonconforming conditions and state law).
• AVMC § 15.86.050–.060 (plans previously approved; illegal uses/structures).
• City interpretation and application rules (Planning Director/appeals) — AVMC interpretation provisions.

Practical internal links used above: Aliso Viejo zoning & planning overview, Aliso Viejo Zoning, Aliso Viejo Development Standards, Aliso Viejo Parking, Aliso Viejo Design Review, Aliso Viejo Overlay Districts, Aliso Viejo ADUs, and the state code reference California Building Standards Code.

Retrieved passages

• Aliso Viejo Zoning Code (section shall) High relevance show source text
• Aliso Viejo Zoning Code (section and) High relevance show source text
• Aliso Viejo Zoning Code (§ 3) High relevance show source text
• Aliso Viejo Zoning Code High relevance show source text
• Aliso Viejo Zoning Code (§ 3) High relevance show source text
• Aliso Viejo Zoning Code Medium relevance show source text
• Aliso Viejo Zoning Code (§ 1) Medium relevance show source text
• Aliso Viejo Zoning Code (section does) Medium relevance show source text
• Aliso Viejo Zoning Code (§ 1) Medium relevance show source text

Cited sections

• AVMC **Chapter 15.86 — Nonconforming Uses, Lots and Structures**: **§ 15.86.010–.060**, including **§ 15.86.020** (continuation/repair/intensification/discontinuance/ restoration) and **§ 15.86.030** (nonconforming lots). (Chapter 15.86)
• AVMC **§ 15.38.170 — Nonconforming parking** (rules on historic parking ratios and expansions). (§ 15.38.170)
• AVMC **residential development standards table** (setbacks, coverage, landscaping) — residential district standards (RL, RM, RH, RVH, PRD). See the residential standards table in the code files.
• AVMC **§ 15.18.030 — Nonresidential development standards** (CT, CC, CN, PO, BP‑1/BP‑2 height, FAR, setbacks). (§ 15.18.030)
• AVMC **§ 15.14.080 — Accessory dwelling units** (how ADUs interact with nonconforming conditions and state law). (§ 15.14.080)
• AVMC **§ 15.86.050–.060** (plans previously approved; illegal uses/structures). (§ 15.86.050)
• City interpretation and application rules (Planning Director/appeals) — AVMC interpretation provisions.
• AlisoViejo_ZoningCode.md