Local zoning · Ross

Ross — Nonconforming Uses

Q: Can I enlarge a nonconforming single‑family house in Ross?

You can sometimes enlarge a nonconforming house in the R‑1 district, but enlargements that increase nonconforming floor area usually require a nonconformity permit approved by the Town Council under § 18.52.040 (or a minor nonconformity permit under § 18.52.045 if the change is very small and meets director-level criteria). The Council’s decision requires specific findings, including proof the structure was lawful when built and that the total floor area will not exceed the greater of existing or current maximum permitted floor area.

Q: If my house predates the current FAR, can an ADU be added without an FAR variance?

Yes — the Code says that floor area associated with an Accessory Dwelling Unit does not require a separate FAR variance when the ADU is built in accordance with Chapter 18.42 and state ADU law; but other nonconforming floor area increases do require a FAR variance. See § 18.52.030(c) and § 18.42.090 . Verify ADU-specific limits and any rent-restriction exceptions in Chapter 18.42.

Q: Who decides a nonconformity permit — Council or staff?

The Town Council reviews and decides standard nonconformity permit applications for the R‑1 and Special Building Site B districts at a public meeting per § 18.52.040(d) . The Planning and Building Director may approve minor nonconformity permits where the criteria in § 18.52.045(b) are satisfied.

Q: What parking will the Town require if I keep nonconforming floor area or add space?

The nonconformity permit findings require the site to have adequate parking (at least the district minimum). If a site lacks covered parking, the Town Council can require covered spaces. The Council may also require additional parking based on total site floor area (for example: 1,300–3,300 sq ft → 3 spaces; >3,300 sq ft → 4 spaces ) as listed in § 18.52.040(f)(9) . District parking minima (e.g., C‑L ) are in the district chapters.

Q: If my property is in a :B combining district, do different lot/yard rules apply?

Yes. :B suffixes (B‑6, B‑10, B‑A, etc.) set different minimum lot area , minimum lot width , and side-yard requirements (see the table in § 18.32.050 ). Nonconformity analysis must be read with the exact :B subdesignation for your parcel. Verify your parcel’s zoning suffix on the Town map and consult Chapter 18.32 .

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

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Last reviewed: July 2, 2026

Overview

This page explains how the Town of Ross treats nonconforming uses, nonconforming structures, and nonconforming lots under the Town’s Zoning Code (Title 18). It summarizes who may apply to keep, alter, or rebuild a nonconforming building or use, what findings the Town requires, and where special processes (nonconformity permit, minor nonconformity permit, demolition rules) apply. For context on related topics you will see links to the Town’s pages on zoning, development standards, design review, parking, overlay districts, ADUs, and the California Building Standards Code where the code itself references state ADU rules.

For the Town-wide zoning map and district list see Ross zoning & planning overview.
For district development standards see Ross Development Standards.
If your project touches parking, see Ross Parking.
If design compatibility is an issue, see Ross Design Review.
If your property sits in a combining district, consult Ross Overlay Districts.
For nonconforming ADUs consult Ross ADUs and note California ADU law and California Building Standards Code.

Key controlling text: the nonconforming provisions sit in Chapter 18.52 (Nonconforming Structures and Uses) and definitions are in Chapter 18.12; the Town’s nonconformity permit procedure and findings are in § 18.52.040 and the minor nonconformity permit in § 18.52.045.

What the Ross Code requires (core rules)

Definitions: A nonconforming structure is “a building or structure or portion thereof which does not conform to one or more regulations of the district in which it is located,” and a nonconforming use is “a use which does not comply with the use regulations in the district in which it is located.” See § 18.12.230 and § 18.12.240.
Continued use and abandonment: Lawfully established nonconforming uses may be continued but if the nonconforming use is discontinued or abandoned for six months or more, the use is presumed abandoned and any subsequent use must conform to the current code. See § 18.52.010(c).
Alterations and enlargement: As a general rule a nonconforming use or structure may not be enlarged, extended, reconstructed, or structurally altered except as the Code permits (exceptions below). See § 18.52.030. Minor exterior alterations that do not increase exterior dimensions are allowed; larger enlargements require compliance with zoning or the nonconformity permit process.
Residential nonconformities and permits: The Town Council may allow enlargement, extension, reconstruction or structural alteration of nonconforming structures in the Single Family Residence and Special Building Site B districts via a nonconformity permit under § 18.52.040; the Planning and Building Director may approve minor nonconformity permits under § 18.52.045 when the changes are limited. The permit process includes public notice and findings (see next).
Mandatory findings to approve a nonconformity permit include proof the structure was lawful when built, design-review conformance, floor area limits, public health and safety, flood and fire protections, indemnification, and adequate parking (including minimum covered parking rules and the chart for added parking when floor area rises). See § 18.52.040(f)(1)–(9). Note the Town may require additional covered parking as a condition.
Floor area variances: Increasing nonconforming floor area typically requires a FAR variance; however, floor area associated with an Accessory Dwelling Unit (ADU) does not require a FAR variance when built in conformance with Chapter 18.42 (ADUs) and applicable state law. See § 18.52.030(c) and § 18.42.090(b).
Applicability dating: The nonconforming rules apply to pre-existing conditions and to new nonconformities created by future amendments to the Title; time limits for suspension are measured from the ordinance that created the nonconformity. See § 18.52.050.
Demolition/replacement: Demolition of a nonconforming structure requires the Demolition chapter findings; if demolition is approved and replacement is required, the Town will not release the building permit for demolition until a permit for the replacement structure is in hand. See § 18.50.060 and § 18.50.100.

District-by-district breakdown (where nonconformities commonly appear)

Below are the Town’s active districts in Title 18 with the sections you must check if you have a nonconforming building or use. Each subsection states the district name in bold, its purpose, typical permitted uses, key dimensional standards, and where that district typically applies.

Single Family Residence (R-1)

Purpose: preserve single-family character of Ross neighborhoods. See § 18.16.020.
Typical permitted uses: single-family residences, accessory uses, ministerial Accessory Dwelling Units, supportive housing, home occupations. See § 18.16.030 and Chapter 18.42 for ADUs.
Key dimensional standards (check these before proposing any enlargement): Minimum lot area: 5,000 sq ft, minimum lot width: 50 ft, minimum lot depth: 100 ft (see § 18.16.040); yard and height rules in § 18.16.050–060; floor area rules in § 18.16.090. For larger lots and B-combining standards see Chapter 18.32.

Where nonconforming rules matter: if your R‑1 house predates current FAR or setback limits and you want to renovate, use § 18.52.040 (nonconformity permit) or § 18.52.045 (minor nonconformity permit). The Town Council (or director for minor cases) applies design-review criteria in § 18.41.100 as part of the findings.

Local Service Commercial (C-L)

Purpose: concentrated small-scale commercial core that serves residents. See § 18.20.020.
Typical permitted uses: multifamily housing (with conditions), retail stores, professional offices; some uses require a use permit (restaurants, banks, gas stations). See § 18.20.025–030.
Key dimensional standards: maximum height two stories / 30 ft, maximum building coverage 100%, maximum FAR 130%, parking minimums and special rules for ground-floor residential. See § 18.20.025, 18.20.040–080.

Where nonconforming rules matter: nonconforming commercial uses or mixed-use buildings must follow § 18.52.010–050; changes that increase floor area or change parking demand will be evaluated using the nonconformity permit findings (including the parking adequacy chart in § 18.52.040(f)(9)).

Civic (C‑D) and Community Cultural (C‑C) Districts

Purpose and uses: C‑D covers public/civic uses; C‑C supports cultural uses (museums, botanic/garden uses) and ancillary residential. See Chapters 18.24 and 18.28. Key C‑C standards: minimum lot area 1 acre, max building coverage 25%, min yards 25 ft front / 15 ft side / 40 ft rear, max height two stories / 30 ft, FAR 20% (see § 18.28.040–090).

Nonconforming implications: institutional or cultural buildings with preexisting encroachments use the nonconforming and demolition chapters when proposing work; the Council considers the community character findings in § 18.50.060.

Public Facilities (P‑F), Open Space (O‑S), Floodway (F)

Purpose: public utilities, parks, open space, and floodway protection. See Chapters 18.30–18.32 for standards and Chapter 15.36 for flood prevention referenced in nonconformity findings. Nonconforming uses/structures in these zones are examined carefully for public-safety, floodplain and environmental compliance as required in § 18.52.040(f)(6).

Special Building Site (Combining :B) and other combining districts

Purpose and application: :B and its variants (B‑6, B‑7.5, B‑10, B‑15, B‑20, B‑A, etc.) tune minimum lot area, side yards, parking, and building coverage for specific parcels. See Chapter 18.32 for the full table and § 18.32.050 for R‑1:B width/side‑yard tables. Special Civic (:CD), Special Open (:O), and Special Hazard (:H) likewise add controls. When a nonconformity sits inside a combining district the nonconformity permit findings apply in context of those minimums.

Quick reference table — decision‑relevant standards and allowed uses

What you need to know	Rule / limit (Ross code)	Code reference
Abandonment presumption for nonconforming use	6 months of discontinuance = prima facie abandonment	§ 18.52.010(c)
Authority to modify nonconforming residential structures	Town Council nonconformity permit (minor director-level permit also allowed)	§ 18.52.040 / § 18.52.045
Required findings to approve enlargement/reconstruction	Proof lawful original construction; design-review conformance; FAR limit (cannot exceed existing or current max); flood & fire checks; adequate parking; indemnification	§ 18.52.040(f)(1)–(9)
Parking tied to enlarged floor area	If site lacks covered parking, Council may require covered spaces; extra parking thresholds: 1,300–3,300 sq ft → 3 spaces; >3,300 sq ft → 4 spaces (used in nonconformity review)	§ 18.52.040(f)(9)
ADUs and nonconforming floor area	ADU floor area need not trigger an FAR variance if built following Chapter 18.42 and state ADU law	§ 18.52.030(c); § 18.42.090(b)
Minimum R‑1 lot size (typical)	5,000 sq ft; min width 50 ft; depth 100 ft	§ 18.16.040

How the nonconformity permit process works (practical steps)

File a Nonconformity Permit application with Planning & Building (forms/fee; Council hears the case) or file for a Minor Nonconformity Permit with the Planning & Building Director if your change meets the limited minor criteria. See § 18.52.040(c) and § 18.52.045(b).
Provide evidence the structure/use was lawful when constructed (owner bears the burden). See § 18.52.040(f)(1).
Expect public notice: at least 10 days mailed notice to owners within 300 ft for Council hearings. See § 18.52.040(e).
Prepare to show design conformity to § 18.41.100 (design review criteria), flood compliance (Chapter 15.36), and a fire‑safety/access/water confirmation from the fire chief. See § 18.52.040(f)(3), (6), (7).
Address parking: show you meet minimum parking for the district and the nonconformity parking table; the Town Council can require covered parking. See § 18.52.040(f)(9).

Checklist

Confirm the structure/use was lawful when constructed and collect evidence (deeds, permits, historic photos) — required by § 18.52.040(f)(1).
Determine whether your project is eligible for a Minor Nonconformity Permit (no increase in floor area or minor visibility/impact) per § 18.52.045(b).
If not minor, prepare a full Nonconformity Permit application to the Town Council with plans and findings support — see § 18.52.040(c)–(d).
Prepare design materials responding to § 18.41.100 standards (neighborhood compatibility, minimizing bulk/mass) — design findings feed the nonconformity review.
Obtain fire department confirmation on access/water or include alternate measures — required by § 18.52.040(f)(7).
Demonstrate adequate parking (district minimums and the nonconformity parking thresholds) — see § 18.52.040(f)(9) and the district parking rules.
Be ready to accept indemnification language under § 18.40.180 if the Council conditions approval.

Risks & Ambiguities

Issue	Why it matters	What to verify
Abandonment after inactivity	Use stopped for 6+ months is prima facie abandonment; you could lose nonconforming status	Check occupancy records, utility bills, lease history; cite § 18.52.010(c).
Burden of proof of lawfulness	Owner must prove the structure/use was lawful when built — missing proof can block permit	Gather permits, permit histories, historical photos, tax records; cite § 18.52.040(f)(1).
Floor Area (FAR) increases	Increasing nonconforming floor area requires an FAR variance unless it is ADU floor area built to Chapter 18.42/state law	Confirm whether the increase is ADU-related (see § 18.52.030(c) and § 18.42.090).
Parking adequacy	Council can require up to 3 or 4 spaces depending on total floor area and can require covered parking	Confirm existing covered parking, calculate site floor area, and prepare parking plan; see § 18.52.040(f)(9).
Historic/resource value concerns with demolition	Demolition approvals consider adverse impacts to historic/architectural value (may block demolition)	If demolition is proposed, prepare a heritage/architectural analysis and consult § 18.50.060.
Combining districts (:B) numeric variations	Minimum lot area/side yard/parking differ by B‑designation (B‑6, B‑10, B‑A etc.)	Verify your parcel’s exact :B suffix on the zoning map and consult Chapter 18.32 (tables) before applying.

Plain-English Summary

If your Ross house or business doesn’t meet today’s zoning rules because it was built earlier, you can usually keep using it — but if you stop using it for six months, you likely lose that protection. Small, invisible repairs are allowed; bigger changes typically need a special nonconformity permit (or a minor permit for limited changes). The Town will expect proof the building/use was legal originally, design review conformity, checks for flood and fire safety, and enough parking — and enlarging nonconforming floor area usually requires a variance unless it’s ADU area built under the ADU rules. See § 18.52.010–050 and Chapter 18.42 for ADUs.

Source References

Ross Municipal Code — Chapter 18.52: Nonconforming Structures and Uses (requirements generally; abandonment; alteration; nonconformity permit; minor nonconformity; applicability) — § 18.52.010–050.
Ross Municipal Code — Definitions of Nonconforming structure and Nonconforming use — § 18.12.230–240.
Ross Municipal Code — Chapter 18.16: Single Family Residence (R‑1) (permitted uses, lot and yard minima) — § 18.16.030–050.
Ross Municipal Code — Chapter 18.20: Local Service Commercial (C‑L) (permitted uses and FAR/height/parking rules) — § 18.20.025–080.
Ross Municipal Code — Chapter 18.28: Community Cultural (C‑C) (lot area, coverage, yards, FAR) — § 18.28.040–090.
Ross Municipal Code — Chapter 18.32: Special Building Site (:B) Districts (B‑suffix lot width/side yard tables and lot area) — § 18.32.030–050.
Ross Municipal Code — Chapter 18.50: Demolition of Structures (findings and replacement-structure rules) — § 18.50.040–100.
Ross Municipal Code — Chapter 18.41: Design Review (criteria referenced in nonconformity findings) — § 18.41.100.
Ross Municipal Code — Chapter 18.42: Accessory Dwelling Units (ADU definitions and nonconforming ADU rules) — § 18.42.090.
2025 California ADU handbook (state ADU rules and relation to nonconforming zoning conditions) — see the uploaded ADU guidance for state‑level constraints and protections.

Sources

Retrieved passages

Ross Zoning Code (Section 18.52.040) High relevance
Ross Zoning Code (Chapter 18.52) High relevance
Ross Zoning Code (Section 18.41.100) High relevance
Ross Zoning Code (Chapter 18.64) High relevance
Ross Zoning Code (Section 18.41.100) High relevance
Ross Zoning Code (§2) High relevance
Ross Zoning Code (section and) High relevance
Ross Zoning Code (section shall) High relevance
Ross Zoning Code (Chapter 18.41) High relevance
Ross Zoning Code (§1) Medium relevance
Ross Zoning Code (§3) Medium relevance
Ross Zoning Code (§ 66333) Medium relevance
Ross Zoning Code (Section 18.20.070) Medium relevance
CBC § 66321 (§ 66321) Medium relevance
CBC § 202 (section 202) Medium relevance
Ross Zoning Code (Section 18.42.055) Medium relevance
Ross Zoning Code (Section 18.12.310) Medium relevance
Ross Zoning Code (Section 18.12.310) Medium relevance
CBC § 010 (Chapter 18.45) Medium relevance
Ross Zoning Code (§10) Medium relevance

Cited sections

Official Ross code library

Frequently asked questions

Can I enlarge a nonconforming single‑family house in Ross?

You can sometimes enlarge a nonconforming house in the R‑1 district, but enlargements that increase nonconforming floor area usually require a nonconformity permit approved by the Town Council under § 18.52.040 (or a minor nonconformity permit under § 18.52.045 if the change is very small and meets director-level criteria). The Council’s decision requires specific findings, including proof the structure was lawful when built and that the total floor area will not exceed the greater of existing or current maximum permitted floor area.

What happens if I stop using a nonconforming commercial activity?

If a lawfully established nonconforming use is discontinued for six months or more, it is presumed abandoned and any subsequent use must conform to current zoning; this is set out in § 18.52.010(c). Documented short-term interruptions do not automatically equal abandonment, but long gaps create a legal risk you will lose nonconforming status.

If my house predates the current FAR, can an ADU be added without an FAR variance?

Yes — the Code says that floor area associated with an Accessory Dwelling Unit does not require a separate FAR variance when the ADU is built in accordance with Chapter 18.42 and state ADU law; but other nonconforming floor area increases do require a FAR variance. See § 18.52.030(c) and § 18.42.090. Verify ADU-specific limits and any rent-restriction exceptions in Chapter 18.42.

Who decides a nonconformity permit — Council or staff?

The Town Council reviews and decides standard nonconformity permit applications for the R‑1 and Special Building Site B districts at a public meeting per § 18.52.040(d). The Planning and Building Director may approve minor nonconformity permits where the criteria in § 18.52.045(b) are satisfied.

What parking will the Town require if I keep nonconforming floor area or add space?

The nonconformity permit findings require the site to have adequate parking (at least the district minimum). If a site lacks covered parking, the Town Council can require covered spaces. The Council may also require additional parking based on total site floor area (for example: 1,300–3,300 sq ft → 3 spaces; >3,300 sq ft → 4 spaces) as listed in § 18.52.040(f)(9). District parking minima (e.g., C‑L) are in the district chapters.

Will design review be applied to nonconforming projects?

Yes. One of the mandatory nonconformity permit findings is that the project “substantially conforms to relevant design review criteria and standards” in § 18.41.100, even if formal design review would not otherwise be required. Expect review against neighborhood compatibility, bulk/mass, and landscape criteria.

If my property is in a :B combining district, do different lot/yard rules apply?

Yes. :B suffixes (B‑6, B‑10, B‑A, etc.) set different minimum lot area, minimum lot width, and side-yard requirements (see the table in § 18.32.050). Nonconformity analysis must be read with the exact :B subdesignation for your parcel. Verify your parcel’s zoning suffix on the Town map and consult Chapter 18.32.

Can the Town force me to replace an older nonconforming building with a new conforming one?

If demolition is proposed, the Town’s demolition rules require findings that replacement will not damage historic/architectural resources and that the redevelopment respects neighborhood character (see § 18.50.060). If a replacement structure is required as a condition of demolition approval, the Town will not issue a permit for demolition until a permit for replacement is secured (§ 18.50.100).

If my nonconforming structure is damaged in a disaster, can I rebuild?

The Ross code defers to separate disaster/reconstruction provisions and the nonconforming chapter; specific allowances exist under the code’s alteration and disaster-recovery chapters. For exact authority and required permits check § 18.52.030 in combination with Chapter 15.56 (Disaster Recovery and Reconstruction) — verify with the Planning & Building Department for parcel-specific rules. Not found in retrieved materials: the full text of Chapter 15.56 in the provided files; verify with the jurisdiction.

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