Local zoning · Mountain View

Mountain View — Nonconforming Uses

Q: What is a nonconforming use in Mountain View?

A nonconforming use is any land use or building lawfully established prior to adoption or amendment of the Chapter 36 rules that does not conform with current use regulations of the district; the local definition is in § 36.60.31 and the continuation rules are in §§ 36.06.60–36.06.80 .

Q: What happens if a nonconforming use stops operating?

If a nonconforming use ceases for six (6) months or more , the ordinance treats it as abandoned and the property must thereafter be used only for conforming uses ( § 36.06.80.f ).

Q: What if my building is badly damaged — can I rebuild it as it was?

If repair or replacement would exceed 50% of the cost of a comparable new building (determined by the Chief Building Official), the nonconforming building may not be reconstructed to accommodate the nonconforming use; otherwise, limited reconstruction within one year may be allowed under certain residential provisions ( § 36.06.80.g and § 36.06.85.f).

Nonconforming Uses under the Mountain View local zoning and planning code, with the controlling citations.

Ask a question free See coverage

Last reviewed: July 3, 2026

Overview

This page explains how the City of Mountain View treats nonconforming uses, nonconforming structures, and nonconforming lots under the local zoning ordinance (Chapter 36). It synthesizes the City’s rules on continuation, amortization, repairs, reconstruction, and administrative relief, and points to the district standards that affect whether and how a nonconformity may remain. For background on mapping and where these rules apply, see Mountain View zoning & planning overview and the City’s [Mountain View Zoning] page.

Key controlling rules are in DIVISION 3: Nonconforming Uses and Structures (Secs. 36.06.60–36.06.95); definitions are at § 36.60.31. The code treats nonconforming uses (what happens on the land) and nonconforming structures (building form or development-standard violations) differently; both are subject to limits on continuation, alteration, and rebuilding.

How to read this page

Bolded terms are the quick scans (district names and standards).
Internal reference links appear on the first natural mention of related topics: [Mountain View Development Standards], [Mountain View Parking], [Mountain View Design Review], [Mountain View Overlay Districts], [Mountain View ADUs], and [California Building Standards Code].

What the ordinance says — plain synthesis of the rules

A use or structure lawfully in place when Chapter 36 was adopted may be continued even if it no longer conforms, provided it was lawful when established (§ 36.06.60) .
Nonconforming land uses without substantial structures (fences, small signs, or buildings under 400 sq ft) can continue for five (5) years from the date they became nonconforming; after five years they must stop or convert to a conforming use (§ 36.06.75) .
Nonconforming uses in buildings have multiple pathways: some may be continued for limited amortization periods (see commercial-in-residential rules below), some may be continued for the life of the structure, and minor extensions/alterations are allowed with limits and administrative approval (§ 36.06.80) .
If a nonconforming use or building is abandoned (ceases) for six (6) months or more, the nonconforming status is lost and the property must thereafter be used only for conforming uses (§ 36.06.80.f) .
If a nonconforming building is damaged or destroyed and repair/replacement would exceed 50% of the cost of a comparable new building (as determined by the Chief Building Official), it may not be reconstructed to accommodate the nonconforming use (§ 36.06.80.g) .
Repairs and maintenance are permitted to keep a nonconforming structure safe, but structural alterations are restricted except as required by law or for seismic retrofits approved by the Chief Building Official (§ 36.06.80.d) .
Nonconforming signs have an amortization period of five (5) years unless a precise plan specifies another date; thereafter they are a public nuisance subject to abatement (§ 36.06.95) .
For some nonconformities the owner may seek administrative relief via a Conditional Use Permit through the Zoning Administrator (see § 36.48 references in the nonconforming sections) — the ordinance lists evaluation criteria (public safety, parking/traffic impacts, neighborhood compatibility, etc.) (§ 36.06.80.a; see § 36.48) .

Decision‑relevant table (quick reference)

Rule / item	What it means	Code reference
Continue nonconforming land use (minor structures)	May continue up to 5 years from nonconforming date; then must cease or conform	§ 36.06.75
Nonconforming commercial/industrial use in an R district	Terminated within 40 years unless a Conditional Use Permit is approved	§ 36.06.80.a
Abandonment	Ceased 6 months or more → nonconforming status lost	§ 36.06.80.f
Repairs & maintenance	Allowed to keep safe; no structural replacement except as required by law or approved seismic retrofit	§ 36.06.80.d
Reconstruction after damage	If repair/replacement > 50% of comparable new building cost → cannot restore nonconforming use	§ 36.06.80.g
Minor residential alteration allowance	≤ 400 sq ft or 25% of original floor area (whichever less) for habitability improvements (admin approval)	§ 36.06.80.d.3
Signs amortization	Nonconforming signs may continue 5 years then must conform or be removed; noncompliant signs are a nuisance	§ 36.06.95
If nonconforming structure expanded in R‑1	If expansion makes the structure > 2× original size, the entire structure must meet current district standards	§ 36.06.85.i

District-by-district breakdown (how nonconforming treatment interacts with zone standards)

The ordinance controls nonconformities citywide, but the practical effect depends on the underlying zoning district standards. Below are the primary districts where nonconformities commonly arise and the controlling standards to check. For the full district tables and maps see [Mountain View Zoning] and the City’s [Mountain View Development Standards].

R‑1 (Single‑Family Residential)

Purpose: R‑1 preserves single‑family character and low density. Typical permitted uses: single‑family homes, customary accessory uses. Key property development parameters include front/side/rear setbacks, height limits, and lot coverage that apply to new construction. Example standards (typical): front setback and second‑story setbacks and max heights indicated in the residential development standards table. Verify specific numeric standards for the parcel under Sec. 36.10. Nonconforming implications: residential structures that don’t meet current setbacks or height rules are defined as nonconforming structures and are subject to repair limits, expansion rules (including the 2× expansion rule described in § 36.06.85.i), and the reconstruction threshold if damaged (§ 36.06.85 and § 36.06.80) .
Where it applies: scattered across existing residential neighborhoods; see zoning map (Sec. 36.04.05) .

R‑2 / R‑3 / R‑4 (Multi‑family residential)

Purpose: higher densities and multi‑unit housing. Typical permitted uses: duplexes, triplexes, apartments, etc. Check § 36.10 (residential zones) for density, FAR, height, open area and parking standards. Nonconforming residential developments have special allowances: a nonconforming residential building in a C or M district may continue for the structural life of the building; a nonconforming residential development destroyed >50% may be rebuilt within one year with same number of units if reconstructed portions meet current development standards for the actual number of units (§ 36.06.85.f) .
Where it applies: multi‑family zones and mixed‑use areas shown on the zoning map.

RMH (Mobile Home) and similar

Purpose: RMH regulates mobile home parks and mobile home subdivisions; standards sit in Sec. 36.12 for setbacks, density, and park design. Nonconforming mobile homes/parks are treated under both the RMH standards and the general nonconforming rules; mobile home park components are also regulated by state housing rules. See Sec. 36.12 for setbacks and development standards and then apply § 36.06 series for nonconforming treatment.
Where it applies: the City’s RMH designated areas.

C (Commercial) and Planned Community (P / precise plans)

Purpose: commercial and planned community districts accommodate retail, offices, restaurants and precise plan‑specific mixed uses. The code treats nonconforming commercial uses differently when located in R districts or areas designated residential in the General Plan — notably the 40‑year termination rule for commercial/industrial uses within R districts unless a Conditional Use Permit is granted (§ 36.06.80.a) .
Where it applies: downtown, neighborhood commercial nodes; consult the zoning map and any applicable precise plan. Nonconforming signs in a P district must meet either the precise plan deadline or the five‑year amortization period (§ 36.06.95) .

M (Manufacturing / Industrial)

Purpose: M districts allow industrial, warehousing, and some commercial uses; standards include FAR, setbacks and landscaping. Nonconforming uses located in M districts are subject to the general rules — for residential uses in an M district the code allows continuation for the structural life of the building (§ 36.06.80.b). For development‑standard nonconformities (height, coverage, parking), repairs and limited alterations are permitted under the nonconforming structure rules (§ 36.06.80.d–g) .
Where it applies: industrially zoned parcels in the city (see zoning map).

Note: The ordinance’s definitions of Nonconforming use and Nonconforming structure (and the list of property development standards) are at § 36.60.31; always check that definition first when evaluating a site.

Checklist — what an applicant must satisfy when proposing actions affecting a nonconforming use/structure

Demonstrate the use or structure was lawfully established prior to the zoning rule or amendment that created the nonconformity (see § 36.06.60)
Confirm whether the nonconforming use has been abandoned (no activity) for 6 months or more; if so, nonconforming rights are lost (§ 36.06.80.f)
If proposing structural repair, replacement, expansion, or reconstruction, calculate whether estimated cost exceeds 50% of a comparable new building — if >50%, nonconforming use generally cannot be restored (chief building official determines cost) (§ 36.06.80.g)
For small residential habitability alterations, confirm the change is ≤ 400 sq ft or 25% of original floor area (admin approval pathway) (§ 36.06.80.d.3)
If the nonconforming use is commercial in an R district and the owner seeks continued legal status beyond amortization, prepare a Conditional Use Permit application addressing the criteria in § 36.06.80.a and the procedures of § 36.48
Confirm parking, loading and landscaping consistency (nonconforming parking/landscaping may be regulated by development review) and consult [Mountain View Parking] and [Mountain View Development Standards] for applicable numerical requirements.
If within an overlay or precise plan area, confirm any additional amortization or compliance dates in the plan itself (see [Mountain View Overlay Districts] and the relevant precise plan) — overlay-specific language may impose separate deadlines.
Verify whether design review or development review is required (e.g., for changes to a nonconforming structure in certain districts) and consult [Mountain View Design Review] and Sec. 36.44/36.54 as applicable.

Risks & Ambiguities

Issue	Why it matters	What to verify
Determining the date the use became nonconforming	Amortization clocks (e.g., 5 years, 40 years) run from that date	Check historical permits/records, business licenses, building permits, and evidence that use was lawful when established; confirm with the City. (§ 36.06.75; § 36.06.80.a)
Reconstruction cost threshold (50%)	Whether rebuilding is allowed to continue the nonconforming use hinges on the Chief Building Official's cost determination	Obtain a professional cost estimate and request an early determination from the Chief Building Official; the ordinance assigns the valuation role to that official (§ 36.06.80.g)
Conditional Use Permit discretion	City applies specified criteria (public need, parking impacts, habitability, appearance) — approval is not guaranteed	Build the CUP application to address the criteria listed in § 36.06.80.a and the procedures in § 36.48; verify hearing/appeal steps.
Interaction with overlays / precise plans	Precise plans can set different amortization dates or requirements (signs in P districts are explicitly handled)	Check the precise plan language for the property and consult [Mountain View Overlay Districts] and the applicable precise plan text (precise plan may supersede general chapter rules) (§ 36.06.95 mentions precise plan interplay)
Whether an alteration counts as “structural”	Minor repairs are allowed; structural changes are restricted	Confirm scope with the Chief Building Official and Planning; the code allows minor alterations ≤ 400 sq ft / 25% for residential units (§ 36.06.80.d.3)
Nonconforming ADUs and recent State law interactions	State ADU law limits local ability to deny ADU permits due to some nonconforming zoning conditions	The local nonconforming rules exist, but State ADU law imposes limits — verify interaction with State ADU law and consult [Mountain View ADUs] and state law sources (Not all of those interactions are spelled out in the retrieved local ordinance) (local code: general nonconforming rules; state law: Gov. Code provisions). Not found in retrieved materials for the local code's ADU-specific treatment.

Plain‑English summary

If your building or business in Mountain View no longer meets today’s zoning rules but was legal when it started, you can usually keep operating — but the ordinance limits how long and under what conditions. Small repairs are allowed, limited upgrades need administrative approval, long‑term commercial uses in residential zones may be amortized, a six‑month inactivity rule causes loss of nonconforming rights, and major damage that costs over 50% of a new building generally ends the nonconforming privilege. Check the exact rule that applies to your parcel and expect to work with the Zoning Administrator or apply for a Conditional Use Permit where needed (§§ 36.06.60–36.06.95).

Information Gaps

The City code excerpts retrieved do not contain the full text of § 36.48 (Conditional Use Permit) procedures and criteria; the nonconforming sections reference § 36.48 but the full CUP procedural text was not present in the retrieved snippets. Verify with the full ordinance text for the CUP application process. Not found in retrieved materials.
Local implementation guidance (forms, fee schedules, historical determination process) and mapping of amortization start‑dates for specific properties are not provided in the snippets — verify with the City of Mountain View Planning Division. Not found in retrieved materials.
Interaction between the Mountain View nonconforming rules and recent state ADU provisions is not explicitly detailed in the retrieved local ordinance snippets; for ADU projects, consult the City’s ADU page and State ADU law. Not found in retrieved materials for local‑specific ADU guidance.

Source References

City of Mountain View Municipal Code, DIVISION 3 — Nonconforming Uses and Structures: § 36.06.60 through § 36.06.95 (nonconforming uses, nonconforming structures, nonconforming signs, amortization, abandonment, repair, reconstruction thresholds)
Definitions: § 36.60.31 (definitions of “Nonconforming structure” and “Nonconforming use”)
R‑1 residential development standards and dimensional table excerpts: Sec. 36.10 (residential standards) — example excerpts in the zoning file (front/side/rear setbacks, heights, parking)
RMH (Mobile Home) district standards: Sec. 36.12 (site area, density, setbacks)
Industrial/commercial district development standards (setbacks, FAR, heights): examples in Sec. 36.20 and connected sections — see zoning standards excerpts for industrial rules
Development review, zoning administrator roles, and applicability for nonconforming situations: Sec. 36.44/36.54 excerpts (development review and zoning administrator duties)

Internal reference pages used for contextual linkage (City‑level menu pages):

Mountain View zoning & planning overview: /us/california/mountain-view
Mountain View Zoning: /us/california/mountain-view/zoning
Mountain View Land Use: /us/california/mountain-view/land-use
Mountain View Development Standards: /us/california/mountain-view/development-standards
Mountain View Parking: /us/california/mountain-view/parking
Mountain View Design Review: /us/california/mountain-view/design-review
Mountain View Overlay Districts: /us/california/mountain-view/overlay-districts
Mountain View ADUs: /us/california/mountain-view/adu
California Building Standards Code (Title 24): /us/california/building-codes

Sources

Retrieved passages

Mountain View Zoning Code (§ 1) High relevance
Mountain View Zoning Code (§ 1) High relevance
Mountain View Zoning Code (chapter or) High relevance
Mountain View Zoning Code (§ 1) High relevance
Mountain View Zoning Code (chapter or) High relevance
Mountain View Zoning Code (§ 1) High relevance
Mountain View Zoning Code High relevance
Mountain View Zoning Code (§ 1) High relevance

Cited sections

Official Mountain View code library

Frequently asked questions

What is a nonconforming use in Mountain View?

A nonconforming use is any land use or building lawfully established prior to adoption or amendment of the Chapter 36 rules that does not conform with current use regulations of the district; the local definition is in § 36.60.31 and the continuation rules are in §§ 36.06.60–36.06.80.

How long can a nonconforming land use without significant structures continue?

Nonconforming land uses that don’t involve buildings (or only minor structures like fences, signs, or buildings under 400 sq ft) may continue for five (5) years from the date they became nonconforming; after that they must cease or convert to a conforming use (§ 36.06.75).

What happens if a nonconforming use stops operating?

If a nonconforming use ceases for six (6) months or more, the ordinance treats it as abandoned and the property must thereafter be used only for conforming uses (§ 36.06.80.f).

Can I repair or modify a nonconforming building?

Routine repairs and maintenance are allowed to keep the structure safe, but structural alterations or replacements are limited except as required by law; minor residential habitability alterations may be allowed if they do not exceed 400 sq ft or 25% of original floor area and are approved by the Zoning Administrator (§ 36.06.80.d.3)

If my commercial business is in an R district, can it stay forever?

No — commercial, industrial or office buildings located in an R district or in areas designated residential in the General Plan must generally terminate within 40 years of becoming nonconforming unless a Conditional Use Permit is approved by the Zoning Administrator under the criteria in § 36.06.80.a.

What if my building is badly damaged — can I rebuild it as it was?

If repair or replacement would exceed 50% of the cost of a comparable new building (determined by the Chief Building Official), the nonconforming building may not be reconstructed to accommodate the nonconforming use; otherwise, limited reconstruction within one year may be allowed under certain residential provisions (§ 36.06.80.g and § 36.06.85.f).

Are there special rules for nonconforming signs?

Yes — nonconforming signs (except window signs) may be continued for five (5) years from when they became nonconforming and must then be brought into compliance or removed; signs that remain noncompliant may be abated as public nuisances (§ 36.06.95).

Can a nonconforming use be enlarged or changed?

Generally no — enlargement, extension, reconstitution or substitution is prohibited unless the use is changed to a permitted use or specific allowances apply (e.g., admin authorization via Conditional Use Permit, extension into parts of the building manifestly designed for that use, minor residential alterations) (§ 36.06.80.d)

Does the City treat residential buildings in commercial/industrial zones differently?

Yes — a nonconforming residential building or mobile home located in a C or M district is allowed to continue for the structural life of the building under § 36.06.80.b.

If I want to convert a structure to an ADU and it’s nonconforming, will Mountain View deny me?

The City’s nonconforming rules apply generally, but State ADU law limits local agencies from denying ADU permits solely because of some nonconforming zoning conditions. The local ordinance snippets retrieved do not fully detail ADU‑specific implementation—consult the City’s ADU guidance and State law for the precise interplay. Not found in retrieved materials for local ADU-specific text.

Ask about any Mountain View property

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

Start Free Trial