Local zoning · Mono County

Mono County — Nonconforming Uses

Q: How long can a nonconforming use be discontinued before it is lost?

If a nonconforming use of land is discontinued for one year or more , the right is generally lost; for a nonconforming building use , the discontinuance period is six months (180 days) . The Director may apply the criteria in § 34.020 in borderline cases.

Q: What happens if a nonconforming building is more than 50% damaged?

If a nonconforming structure is damaged or destroyed to 50% or more of its value, it must be rebuilt to meet the current General Plan/regulations unless a use permit allows otherwise. Single‑family homes have an exception that can allow rebuilding as originally permitted when the owner proves the prior nonconformance was legally permitted. § 34.020 .

Nonconforming Uses under the Mono County local zoning and planning code, with the controlling citations.

Ask a question free See coverage

Last reviewed: July 3, 2026

Overview

This page summarizes how the Mono County Land Development Regulations treat nonconforming uses, structures, and lots in the unincorporated areas of Mono County. It is grounded in the Mono County Land Use Element and Land Development Regulations (commonly Title 17 / the Land Development Regulations). Key rules are in § 34.010 and § 34.020 (Nonconforming Uses) and related development-standards chapters; definitions appear in § 02.850.

Note: this guidance applies only to Mono County’s unincorporated areas; incorporated towns have their own codes. For related rules on parking, setbacks, and other technical standards consult the Mono County Development Standards and Parking pages.

Mandatory legal foundation (what the code says, in plain English)

Lawful uses, buildings, structures or lots that were legal when the land-use map/regulations took effect may continue as nonconforming uses but are subject to the limits and processing rules in Chapter 34 (notably § 34.010 and § 34.020) of the Land Development Regulations.
The code defines "Nonconforming" as an existing lawful use, building, or structure that does not comply with later-adopted regulations (§ 02.850) for the land development regulations.
Alterations, expansions or continuations of nonconforming uses/structures are limited: expansions must not increase the use intensity, must be consistent with General Plan intent, and may be subject to Director or Planning Commission review under the criteria in § 34.020.
Discontinuance rules differ by type: for a nonconforming land use, discontinuance for one year typically causes loss of the nonconforming right; for a nonconforming building use, discontinuance for six months (180 days) typically causes loss of the right; in both cases the Director may find reuse infeasible and allow alternatives under the criteria in § 34.020.
Nonconforming structures that do not meet current yard, height, parking, coverage or other development standards may remain, but may not be expanded except for minor health/safety repairs unless an expansion meets § 34.020 criteria. If a nonconforming structure is damaged or destroyed to 50% or more of its value it must be rebuilt to current requirements — except single‑family homes have an express exception allowing rebuilding to original permitted form when destroyed beyond 50% if evidence shows the prior nonconformance was legally permitted.
Mobile-home and RV parks legally established before the current regulations are treated as nonconforming lots under § 17.040: they may continue the park use and may expand to use the entire nonconforming parcel with a use permit; conversions between RV and mobile-home spaces are allowed with a use permit subject to yard/installation requirements.
Nonconforming signs follow Chapter 07: expansion or increased lighting of nonconforming signs is prohibited; copy may change; if a nonconforming sign is destroyed to 50% or more of its replacement cost it must be brought into conformance before replacement. See § 07.070.

District-by-district breakdown (how rules interact with common Mono County land use designations)

Note: every district below is a county UNINCORPORATED land use designation from the Mono County Land Use Element. Where I cite required development standards (setbacks, lot coverage, height, minimum lot), those standards are in the Land Use Element and the Land Development Regulations; see the county Zoning and Land Use pages for maps and area plans.

MFR-L, MFR-M, MFR-H (Multi-Family Residential, Low/Moderate/High)

Purpose: encourage multifamily housing at different densities (low to high). MFR-H permits commercial lodging where MFR-L/M may not.
Typical permitted uses: single-family dwellings, duplexes, triplexes, accessory buildings, multifamily units; certain uses require Director Review or Use Permit (condominiums, parking structures, etc.).
Key dimensional standards (examples): minimum lot size: generally 7,500 sf for single-family; maximum lot coverage: MFR-L 40%, MFR-M/H 60%; maximum height varies (see Table 04.010). These affect whether an existing building is nonconforming for lot coverage, height or setbacks.
Where it applies: developed/unincorporated communities mapped in the General Plan. Nonconforming multifamily conversions/extensions must still respect § 34.020 (no increase in use‑category intensity).

IP (Industrial Park) and I (Industrial)

Purpose: industrial/light-industrial uses; I allows heavier industry.
Typical uses: warehouses, light manufacturing, vehicle repair, storage yards; many uses allowed only with Director Review or Use Permit.
Key standards: minimum lot area typically 10,000 sf (district-specific), maximum lot coverage up to 80%, max height often 40'; setback rules apply and may make an existing structure nonconforming.
Where it applies: industrial areas in unincorporated Mono County. Nonconforming industrial structures may be repaired but expansions that change intensity must satisfy § 34.020.

RU (Rural Resort), RR (Rural Residential), RMH (Rural Mobile Home)

Purpose: rural, resort, and larger‑lot residential contexts. Typical permitted uses include single‑family dwellings, accessory uses, small‑scale agriculture; certain resort/lodging or mobile-home park uses may require permits.
Key dimensional standards: minimum parcel sizes range (e.g., RU 5 acres, RR 1 acre), front/side/rear setbacks (examples RU front 30', side 30', rear 30'; RR front 50', side 30', rear 30'). Nonconforming buildings in these districts are typically ones that now exceed allowed coverage or sit inside new setbacks.
Where it applies: unincorporated rural and resort areas; repairs to nonconforming structures allowed only to the limited extent in § 34.020.

Mobile‑home / RV parks (special treatment) — Chapter 17 / § 17.040

Purpose & special rule: existing parks legally established before current regulations are deemed nonconforming lots and are allowed to continue the park use; a park on a nonconforming lot may expand to use the entire nonconforming parcel if a use permit is secured. Conversions between RV and mobile‑home spaces require a use permit and must meet installation and yard requirements. § 17.040.

Quick reference decision table (most decision‑relevant rules)

Topic	Rule / Permit trigger	Code reference
Lawful continuation of nonconforming uses	Existing lawful uses may continue but are limited in alteration, expansion, and replacement	§ 34.010, § 34.020
Discontinuance — land use	If nonconforming land use discontinued for 1 year, subsequent use must conform (unless Director finds infeasible and applies § 34.020 criteria)	§ 34.020
Discontinuance — building use	If nonconforming building use discontinued 180 days, subsequent use must conform (Director may apply § 34.020)	§ 34.020
Damaged/destroyed nonconforming structure	If ≥50% destroyed, must be rebuilt to current requirements; exception for single‑family homes (may rebuild as originally permitted with proof)	§ 34.020
Nonconforming signs	No increase in size/lighting; copy may change; ≥50% destruction requires conformance on rebuild	§ 07.070
Mobile‑home / RV parks on nonconforming lots	Existing parks on undersized lots may continue; may expand across parcel with a Use Permit; conversions allowed with Use Permit and yard compliance	§ 17.040
Definition of nonconforming	"Nonconforming" = lawful existence/use that conflicts with later regulations	§ 02.850

Practical guidance & synthesis (how to approach an application)

Before filing, confirm whether the prior use was lawful at the time the current designation/regulations took effect — that legal origin is what creates a nonconforming right (§ 02.850, § 34.010). If records are thin, be prepared to submit historic permits, business licenses, photographs, tax records, affidavits and other proof.
If you want to repair, alter, or slightly expand a nonconforming structure, frame the proposal around health/safety improvements or minor work. Major expansions or anything that increases the “intensity of use” will be evaluated under the criteria in § 34.020 (consistency with General Plan, public welfare, not increasing intensity, potential referral to Planning Commission).
If the nonconforming structure was destroyed beyond 50% of its value, expect to redesign to meet current standards unless it’s a single‑family home and you can prove the prior nonconformance was legally permitted. Use permits may be available for deviations but will be discretionary. Verify with the jurisdiction in property‑specific situations.
For ADUs: Mono County must still follow state ADU rules. State law limits denial of ADUs where the issue is correcting nonconforming zoning conditions that do not threaten health/safety. Consult California ADU law and Mono County’s ADU chapter and permit process for details; state ADU rules may preempt some local nonconforming conditions when processing ADUs.
When work triggers review (e.g., Use Permit, Director Review, Design Review), be ready to address related topics: parking (Parking), setbacks and development standards (Development Standards), design review (Design Review), overlay rules (Overlay Districts), signage (Signage), landscaping/screening (Landscaping and Screening), and any variance needs (Variances and Exceptions).

Checklist (what an applicant must satisfy / submit for a typical nonconforming-use request)

Evidence the use/structure was lawful on the effective date of the current land‑use designation (permits, tax records, photos). § 02.850, § 34.010.
Site plan showing existing nonconforming dimension(s) (setbacks, lot coverage, height), current use intensity, and the proposed changes. (See Development Standards).
Written explanation showing proposed alterations will not increase “use‑category intensity” and meet § 34.020 criteria A–D if an enlargement is sought. § 34.020.
If the structure was partially destroyed, provide damage estimates and valuation (to determine the 50% threshold) and, if applicable, evidence for the single‑family exception. § 34.020.
Any required environmental review, building permits, and compliance with the California Building Standards Code for structural or occupancy changes. Verify with the jurisdiction.
If converting uses (e.g., RV to mobile home spaces), a Use Permit application with plans demonstrating compliance with yard and installation standards (see § 17.040).

Risks & Ambiguities

Issue	Why it matters	What to verify
Whether the prior use was legally established	Nonconforming rights attach only to lawful uses active when the new rules took effect — weak proof can lead to removal or enforcement.	Request historic records from County, building permits, business licenses, tax records; ask Planning to confirm. § 02.850
Discontinuance timing (land 1 year vs building 180 days)	Different discontinuance periods can change whether the nonconforming right survives; misdating cessation can be determinative.	Verify date the use ceased, whether seasonal use exception applies, and the Director’s interpretation. § 34.020
Rebuild after ≥50% destruction	If a building is over the 50% damage threshold it must meet current code — major cost and design implications; single‑family exception is narrow and requires proof.	Provide replacement‑cost valuation. Confirm whether single‑family exception applies. § 34.020
“Increase in intensity” ambiguity	The phrase is discretionary and can trigger denial of an expansion if it’s effectively a larger or more intensive use.	Prepare traffic, parking, and neighborhood impact analyses; meet with Planning staff early. § 34.020.C
Interaction with state ADU law	State ADU rules limit local denial when nonconforming conditions are merely zoning nonconformance and not health/safety threats.	For ADU proposals, check state ADU rules and Mono County ADU chapter; do not assume local nonconformances automatically block ADUs.
Parcel changes (subdivision) affecting signs/lots	A lot split can force nonconforming signs or uses to conform to the new lot’s rules — unintended loss of rights possible.	If subdividing, include sign/use conformity assessment; consult § 07.070 for signs and § 04.080 for lot area rules.

Plain-English Summary

If a use or building in unincorporated Mono County was legal when the current zoning rules began, you usually can keep it — but changes are limited: you generally cannot enlarge the use or rebuild bigger after major destruction without meeting current rules or getting a discretionary permit; some special rules apply to mobile‑home parks and signs. See § 34.010 and § 34.020 for the controlling tests and § 17.040 for mobile‑home/RV parks.

Source References

§ 34.010 – General provisions and § 34.020 – Alterations to nonconforming uses, buildings and structures (Chapter 34, Nonconforming Uses) — Mono County Land Development Regulations.
§ 02.850 – "Nonconforming" definition (Definitions chapter).
§ 17.040 – Existing mobile‑home parks and recreational‑vehicle parks (nonconforming lots).
§ 07.070 – Nonconforming Signs (Chapter 07 — Signs).
Land use designation materials for MFR-L / MFR-M / MFR-H, IP, I, RU, RR, RMH (development standards, permitted uses, setbacks, lot size excerpts).
Mono County Land Development Regulations table of contents / chapter listing (to cross‑check chapter/section numbers).
State ADU summary and limits on denying ADUs for nonconforming zoning conditions (2025 ADU handbook).

Sources

Retrieved passages

Mono County Zoning Code (chapter are) High relevance
Mono County Zoning Code (Chapter 7.20) High relevance
Mono County Zoning Code (section 17.090.) High relevance
Mono County Zoning Code (Section 47) High relevance
Mono County Zoning Code (chapter shall) Medium relevance
Mono County Zoning Code (Chapter 7.20) Medium relevance
CBC § 66314 (§ 66314) Medium relevance
Mono County Zoning Code (CHAPTER 17) Medium relevance
CBC § 202 (section 202) Medium relevance
Mono County Zoning Code (Chapter 25) Medium relevance
Mono County Zoning Code (Chapter 19) Medium relevance
Mono County Zoning Code (chapter shall) Medium relevance
Mono County Zoning Code (chapter and) Medium relevance
Mono County Zoning Code (Section 04.270) Medium relevance
Mono County Zoning Code (Section 04.270) Medium relevance
Mono County Zoning Code Medium relevance
Mono County Zoning Code (chapter shall) Medium relevance
Mono County Zoning Code (§ 66314) Medium relevance
Mono County Zoning Code (Section 07.030) Medium relevance

Cited sections

Official Mono County code library

Frequently asked questions

What is a nonconforming use in Mono County?

A nonconforming use in unincorporated Mono County is a land use, building, or structure that lawfully existed when current land development rules became effective but which does not comply with those later rules; the definition is in § 02.850 and the continuation rules are in § 34.010.

How long can a nonconforming use be discontinued before it is lost?

If a nonconforming use of land is discontinued for one year or more, the right is generally lost; for a nonconforming building use, the discontinuance period is six months (180 days). The Director may apply the criteria in § 34.020 in borderline cases.

Can I expand a nonconforming building or use in unincorporated Mono County?

Expansions that would increase the intensity of the use are generally not allowed. Minor structural alterations for health/safety are allowed; larger changes must meet the discretionary criteria in § 34.020 (consistency with the General Plan, no substantial detriment to public welfare, no increase in use intensity, and possible Planning Commission review).

What happens if a nonconforming building is more than 50% damaged?

If a nonconforming structure is damaged or destroyed to 50% or more of its value, it must be rebuilt to meet the current General Plan/regulations unless a use permit allows otherwise. Single‑family homes have an exception that can allow rebuilding as originally permitted when the owner proves the prior nonconformance was legally permitted. § 34.020.

Do mobile‑home parks on undersized lots lose their rights?

No — existing mobile‑home parks and RV parks legally established before the current rules are deemed nonconforming lots and may continue park use. A mobile‑home park on an undersized (nonconforming) lot may expand to utilize the entire parcel with a Use Permit; conversions between RV and mobile‑home spaces are allowed with a Use Permit subject to yard and installation requirements (see § 17.040).

Are nonconforming signs allowed to be upgraded or relit?

Nonconforming signs may not be increased in area or lighting intensity; the sign copy (message) may be changed. If a nonconforming sign is destroyed to 50% or more of its replacement cost, replacement must conform to the sign chapter rules. See § 07.070.

Can Mono County require removal of a nonconforming animal keeping practice?

The County explicitly allows nonconforming animal numbers to persist without increase, but the Board of Supervisors may declare the keeping of nonconforming animals a public nuisance (upon recommendation) and abate per Chapter 7.20 if the use is dangerous or prevents neighboring property enjoyment. See § 34.020 (Nonconforming Animals).

Will state ADU rules let me build an ADU on a property with zoning nonconformance?

State ADU law limits a local agency’s ability to deny ADUs solely because of nonconforming zoning conditions that do not create a health/safety threat. Consult Mono County’s ADU chapter and State ADU law; state rules may constrain local denial in some ADU cases.

If I subdivide a parcel, what happens to nonconforming uses or signs?

Subdivision or lot/configuration changes can force nonconforming signs and some uses to conform to the new lot’s regulations once the change is effective; Chapter 07 for signs and § 04.080 on lot area are relevant. Verify with Planning before dividing a parcel.

Who enforces Mono County’s nonconforming‑use rules?

Enforcement duties fall to County staff: the Community Development Director and other directors (Building Official, Environmental Health) enforce use of land, building height, setbacks, and health-related issues; enforcement procedures appear in Chapter 49. Verify enforcement details with Mono County Planning. ---

Ask about any Mono County property

Get a cited, plain-English answer on Mono County zoning, setbacks, FAR, ADUs and permits — for any address.

Start Free Trial