Local zoning · San Anselmo

San Anselmo — Nonconforming Uses

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

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Last reviewed: July 2, 2026

Overview

San Anselmo treats nonconforming uses, buildings, and lots as legacy conditions that may be continued in limited ways but are subject to strict rules on expansion, abandonment, replacement, and repair. The controlling rules are in the Town zoning chapter: Article "Nonconforming uses and improvements" and related development standards (see § 10‑3.607, Table 4A, and the ADU chapter). The short versions: you generally may maintain and repair, you may not enlarge a nonconforming use, and destruction or long abandonment can force conformance — but there are important, use‑specific exceptions (e.g., ADUs and gas stations).

What the San Anselmo code says — core rules, in plain terms

  • Continuing an existing lawful, but now nonconforming, use is allowed in many situations; however, certain outdoor, non-built commercial activities were specifically prohibited to continue after fixed historical dates (see § 10‑3.607(b)).

  • Abandonment / automatic loss: if a nonconforming use is abandoned or discontinued for six (6) months or more, the site must be brought into conformity and the nonconforming status is lost (§ 10‑3.607(b)(2)).

  • No expansion of nonconforming uses: nonconforming uses and buildings dedicated to nonconforming uses shall not be expanded or intensified (see § 10‑3.607(c)).

  • Replacement/destruction: if a nonconforming building is destroyed or 50% or more of exterior walls above the foundation are demolished, the site becomes subject to current district regulations unless the owner rebuilds a replacement‑in‑kind within the exceptions described (see § 10‑3.607(e)(1)(i–ii)). The Planning Director may publish guidelines measuring exterior wall demolition.

  • Repair/alteration of nonconforming buildings: maintenance, repair, and structural alteration are allowed, but enlargements or alterations must comply with the zone’s current use, setback, height, lot coverage and other site development requirements (or meet a listed exemption such as Table 4B) — see § 10‑3.607(f).

  • Parking when you change/repair: when a nonconforming structure is maintained, repaired, enlarged, extended, or structurally altered, parking must comply with the parking requirements of the zone in which the structure is located (see § 10‑3.520(c) and the Town parking rules).

  • Use‑specific rules: the code contains a dedicated section for nonconforming gas stations that allows limited modifications (including EV charging) but prohibits enlarging or moving fossil‑fuel infrastructure and sets strict abandonment and removal rules (§ 10‑3.610).

  • ADUs and nonconforming conditions: the ADU chapter explicitly says the Town shall not require correction of nonconforming zoning conditions as a condition of ADU or JADU approval, and the Town shall not deny an ADU permit for nonconforming zoning conditions or non‑life‑safety building violations unless they present a threat to health and safety (see the ADU chapter, 10‑6.x).

  • Table references: detailed dimensional standards (minimum lot area, setbacks, lot width, lot coverage, height, density) are in Table 4A (Development Standards); minor intrusion/administrative exceptions are in Table 4B and handled under Article 14.5. See § 10‑3.406, § 10‑3.407, and Table 4A for the numeric standards that govern replacement or enlargement of nonconforming buildings.

District-by-district breakdown (what matters for nonconforming structures/uses)

Below are the Town’s primary zoning districts that commonly produce nonconforming situations. For permitted uses see the Land Use Regulations (Table 3A); for numeric development standards see Table 4A. I summarize the code language (purpose, typical permitted uses from Table 3A, key dimensional standards as stated in Table 4A, and where these districts apply) — always verify a parcel’s mapped district with the Town.

Note: where I state numeric standards I cite Table 4A; confirm parcel‑specific measurements (Verify with the jurisdiction).

R-1‑H (Single‑Family Hillside)

  • Purpose: hillside/residential with special development controls to minimize visual/soil impacts; R‑1‑H projects require additional precise development plans and often stricter design review. See the R‑1‑H provisions and ridge/ridgeline limits.
  • Typical permitted uses: single‑family residential and accessory uses (ADUs allowed as regulated in the ADU chapter). See Table 3A for specific accessory uses.
  • Key standards (Table 4A): Minimum lot area 43,560 sq ft, minimum lot width 60' average; front and rear setbacks 20' (Table 4A columns for R‑1‑H); design review and ridgezone height caps apply. Verify parcel slope provisions (Table 4C).
  • Where applied: mapped hillside single‑family areas (see Town zoning map).

R-1‑C (Single‑Family — Conservation)

  • Purpose: single‑family with conservation constraints; similar to R‑1‑H but with slightly different development controls where mapped.
  • Typical uses: single‑family and accessory uses; ADUs per Chapter 6.
  • Key standards: Minimum lot area 43,560 sq ft, minimum lot width 60', front setback 20', rear 20' (Table 4A). Design review often required for hillside portions.

R-1 (Single‑Family)

  • Purpose: standard single‑family residential.
  • Typical uses: single‑family dwelling, accessory buildings, ADUs (see 10‑6.x).
  • Key standards (Table 4A): Minimum lot area 7,500 sq ft, front/setback 20', max lot coverage ~35% (Table 4A entries apply — consult Table 4A for parcel‑specific numbers).

R-2 (Two‑Family)

  • Purpose: smaller‑lot residential and duplex opportunities.
  • Typical uses: two‑unit residential, small multifamily compatible uses. See Table 3A for detailed allowed uses.
  • Key standards (Table 4A): Minimum lot area 7,500 sq ft, front setback 20', density/min/max per Table 4A.

R-3 (Multifamily)

  • Purpose: medium‑density residential and professional uses where shown on map.
  • Typical uses: multifamily dwellings (two‑to‑four units and up), certain institutional uses. See Table 3A.
  • Key standards (Table 4A): Minimum lot area 7,500 sq ft, lot width min 75', front setback 20', max lot coverage 50% (Table 4A).

P (Public / Institutional)

  • Purpose: public and quasi‑public facilities; development standards often different (see Table 4A).
  • Typical uses: schools, government buildings, parks (permitted uses in Table 3A).
  • Key standards: per Table 4A (smaller lot area minima such as 5,000 sq ft in many instances) and specific setbacks; parking rules apply when nonconforming structures are altered.

C‑1, C‑2, C‑3 (Commercial districts) and C‑L (Limited Commercial)

  • Purpose:
    • C‑1/C‑2/C‑3: neighborhood to general commercial; mixed uses encouraged in certain locations. C‑3 is general commercial along corridors.
    • C‑L: limited/commercial for low‑trip generators along Sir Francis Drake Blvd; stricter traffic standards.
  • Typical permitted uses: retail, offices, restaurants (subject to Table 3A). Mixed use and upper‑floor residential allowed in many C districts (see Table 3A).
  • Key standards (Table 4A): commercial districts commonly show 0' front setback for commercial frontage, varying lot coverage and min lot widths; check Table 4A for exact values for C‑1, C‑2, C‑L, C‑3.

How this affects nonconformities:

  • If a nonconforming commercial building is altered the code requires parking to be brought into compliance for the new intensity (exceptions exist, notably in C‑2 for existing buildings — see parking intensification rules). § 10‑3.520 controls parking on change/alteration.

Quick numeric reference (decision‑relevant) — examples from Table 4A

Standard / Permit issue Typical value or rule (San Anselmo) Code Reference
Abandonment period to lose nonconforming status 6 months (loss if discontinued 6+ months) § 10‑3.607(b)(2)
Destruction threshold triggering conformance 50% or more of exterior walls demolished (above foundation) § 10‑3.607(e)(1)(i)
Expansion of nonconforming use Prohibited (no enlargement/intensification) § 10‑3.607(c)
Parking on alteration of nonconforming structure Must comply with zone parking when maintained/repaired/enlarged/altered § 10‑3.520(c)
ADU approvals & nonconforming conditions Town shall not require correction of nonconforming zoning conditions as an ADU condition ADU chapter 10‑6.x (see ADU nonconformance language)
Special rules for gas stations May be modified in limited ways (EV charging allowed); cannot enlarge fossil‑fuel infrastructure; abandonment = 180 days for gas station nonconforming status loss § 10‑3.610
Dimensional standards (example) R‑1: min lot 7,500 sq ft, front setback 20', lot coverage ~35% (see Table 4A) Table 4A / § 10‑3.403 & § 10‑3.406

Checklist — what an applicant must satisfy if working on a nonconforming property

  • Confirm the property’s mapped zoning district on the Town’s Zoning Map (verify R‑1, R‑1‑H, C‑L, etc.) and consult Table 4A for numeric standards.
  • Determine whether the existing use is a lawful nonconforming use and when/if it was discontinued (6‑month rule). § 10‑3.607(b)(2)
  • If the work is repair, enlargement, or structural alteration, confirm whether the change must meet current setbacks, height, lot coverage and parking for the zone (or whether the work fits an exemption in Table 4B). § 10‑3.607(f) and § 10‑3.14.504
  • For ADUs, note the ADU chapter prohibition on conditioning approval on correcting nonconforming zoning conditions; still check life/safety issues. 10‑6.x
  • For gas stations, follow § 10‑3.610 special rules (no fossil‑fuel enlargement; 180‑day gas station abandonment rule).
  • If demolition or substantial work triggers the 50% exterior wall rule, expect to comply with current district standards unless replacement‑in‑kind exceptions apply. § 10‑3.607(e)
  • If parking is an issue (enlargement/change of use), prepare to provide additional parking per Table 5A and § 10‑3.520 — consult the Town parking page.
  • Where design/visual impact are relevant (hillside/ridge or Table 4B items), be ready for design review or Planning Commission review and associated findings.

(Helpful links: the Town’s development standards, parking, ADUs, design review, zoning, land use, and overlay districts pages are frequently needed.)

Risks & Ambiguities

Issue Why it matters What to verify
Was the use lawfully established originally? If an earlier use was never lawfully permitted, nonconforming protections may not apply. Verify historic permit records/land use approvals with the Town. Not found in retrieved materials — confirm with the Town.
Whether a period of abandonment has occurred 6 months of discontinuance can extinguish nonconforming status (§ 10‑3.607(b)(2)). Confirm continuous operation dates and evidence (utility bills, business records).
Extent of demolition (50% wall rule) Demolition or cumulative work that equals/exceeds 50% of exterior walls triggers full conformance. Obtain the Town’s demolition/alteration interpretation and the Planning Director’s guidelines on measuring exterior wall demolition. § 10‑3.607(e)
Parking obligations if altering a nonconforming structure Alteration or intensification can require additional parking. Verify required spaces under Table 5A and § 10‑3.520; check exemptions (C‑2 exceptions, ADU rules).
ADU interplay with nonconforming zoning ADU chapter limits the Town’s ability to require correction of nonconforming conditions, but life/safety and flood rules still apply. Confirm which ADU subsection applies (10‑6.1xx/10‑6.3xx) and any flood or heritage‑tree constraints.
Gas station special treatment Gas stations have unique rules including 180‑day fuel cessation = loss of nonconforming status. If a gas station, verify fuel sales history/date of cessation and required tank removal obligations. § 10‑3.610

Plain‑English summary

If your San Anselmo property is “grandfathered” (nonconforming), you can generally maintain and repair it, but you cannot expand the nonconforming use or enlarge the building without meeting current zoning standards; long periods of inactivity, major demolition, or use‑specific rules (like those for gas stations) will terminate the nonconforming status and require full compliance. Always check Table 4A (development standards), the ADU chapter, and consult the Planning Department for parcel‑specific verification.

Source References

  • San Anselmo Municipal Code — Nonconforming uses and improvements: § 10‑3.607 (Nonconforming uses and improvements)
  • San Anselmo Municipal Code — Replacement/repair rules: § 10‑3.607(e)–(f) (replacement after destruction; maintenance/alteration)
  • San Anselmo Municipal Code — Nonconforming gas stations: § 10‑3.610 (special rules, EV allowance, 180‑day abandonment/removal)
  • San Anselmo Municipal Code — Parking and expansion rules: § 10‑3.519 and § 10‑3.520 (existing structures, parking on enlargement/alteration)
  • San Anselmo Municipal Code — Development Standards Table: Table 4A and setback/height exceptions § 10‑3.406 (see Table 4A for district numeric standards)
  • San Anselmo Municipal Code — Land Use Regulations (Table 3A): Table 3A (permitted/conditional uses by district)
  • San Anselmo Municipal Code — ADU chapter: Chapter 6 (10‑6.x) (ADU rules including nonconforming condition protections, parking exemptions and flood/heritage tree provisions)
  • Design review findings and procedure (Article 15 / § 10‑3.1506) — affects design‑sensitive nonconforming projects.

(If you want direct links to these specific Town pages, I can pull the exact ordinance text and map references or prepare a parcel‑specific checklist you can bring to the Planning counter. Verify with the Town for parcel‑level determinations.)

Sources

Retrieved passages

  • San Anselmo Zoning Code (§ 1) High relevance
  • San Anselmo Zoning Code (article shall) High relevance
  • San Anselmo Zoning Code (Section and) High relevance
  • San Anselmo Zoning Code (Section 10-3.405) High relevance
  • San Anselmo Zoning Code (§ 4) High relevance
  • San Anselmo Zoning Code (chapter is) High relevance
  • San Anselmo Zoning Code Medium relevance
  • San Anselmo Zoning Code (§ 2) Medium relevance
  • San Anselmo Zoning Code (Section 10-1305) High relevance
  • California Fire Code (Title 7) Medium relevance
  • CBC § 310 (Section 310) Medium relevance
  • CFC § 100 (Title 7) Medium relevance
  • San Anselmo Zoning Code (§ 1) Medium relevance
  • San Anselmo Zoning Code (Article 1) Medium relevance
  • San Anselmo Zoning Code (Section 10-3.1506) Medium relevance
  • San Anselmo Zoning Code (Section 10-3.1404) Medium relevance
  • San Anselmo Zoning Code (Chapter 4) Medium relevance
  • San Anselmo Zoning Code (section for) Medium relevance
  • San Anselmo Zoning Code Medium relevance
  • San Anselmo Zoning Code (Title 11) Medium relevance
  • CPC § 10 (Section 10-6.103) Medium relevance
  • San Anselmo Zoning Code (§ 66314) Medium relevance
  • San Anselmo Zoning Code (§ 66333) Medium relevance
  • San Anselmo Zoning Code (§ 3) Medium relevance
  • CBC § 66314 (§ 66314) Medium relevance

Cited sections

Frequently asked questions

What happens to a nonconforming use if it stops operating for more than six months?

If a lawful nonconforming use is discontinued or abandoned for six (6) months or more, the property must be brought into conformity — the nonconforming status is lost. See § 10‑3.607(b)(2) for the rule.

If my nonconforming building is damaged in a fire, can I rebuild the same way?

If 50% or more of the existing exterior walls above the foundation are demolished or the building is destroyed by fire, the property becomes subject to current district regulations unless the rebuild is a narrow "replacement in kind" exception. See § 10‑3.607(e)(1) and consult the Planning Director’s guidelines on demolition measurement.

Can I add an ADU to a property with nonconforming setbacks or lot coverage?

Yes — the ADU chapter says the Town shall not require correction of nonconforming zoning conditions as a condition of ADU or JADU approval, and it may not deny an ADU solely for nonconforming zoning conditions or non‑life‑safety building violations (subject to limited exceptions for safety). See the ADU rules in Chapter 6 (10‑6.x).

If I enlarge a nonconforming commercial building, do I have to add parking?

When an existing nonconforming structure is enlarged, altered, or the use is intensified, additional off‑street parking is required as the ordinance prescribes (exceptions exist for certain C‑2 situations and ADUs). See § 10‑3.520.

May a nonconforming gas station add EV chargers or renovate?

Yes — San Anselmo allows certain modifications to nonconforming gas stations (including accommodating Zero‑Emissions Fueling Stations and façade/site improvements) but prohibits enlarging fossil‑fuel storage/dispensing infrastructure and relocating tanks; see § 10‑3.610 for detailed limits and the 180‑day abandonment rule.

What numeric setbacks, heights, and lot sizes apply if I must bring a property into conformance?

Numeric standards are in Table 4A (Development Standards) for each district (R‑1, R‑1‑H, R‑1‑C, R‑2, R‑3, P, C‑1, C‑2, C‑L, C‑3). Table 4A lists min lot area, min lot width, front/rear setbacks, lot coverage, and height limits — refer to Table 4A and § 10‑3.403/§ 10‑3.406 for measurement rules.

Can I get a minor exception if maintaining a small intrusion into a required setback?

Yes — small intrusions are reviewed under the minor exception rules (Table 4B / Article 14.5) and require specific findings (de‑minimis impact, light/air/privacy, and an upper limit of 100 sq ft expansion for many items). See 10‑3.14.504 – 10‑3.14.505.

If my property was legally built before the current code but is undersized, can I rebuild?

A lot or building site smaller than current minimums may be used for permitted construction if it met certain historic subdivision or ownership tests and if all other chapter requirements are met — see § 10‑3.408 and the exceptions in Table 4A. Verify with the Planning Department for lot‑specific eligibility.

Do design review or ridge/ridgeline rules change how nonconforming hillside homes are handled?

Yes — R‑1‑H and other hillside parcels are subject to additional design and ridgezone findings; height limits above ridgelines and stricter design review can limit rebuilds or enlargements on visible hillsides. See the ridge/ridgeline rules and Article 15 design review findings.

Where do I check permitted uses to know whether a use is nonconforming in my district?

Consult the Town’s Land Use Regulations Table (Table 3A): it shows whether a use is Permitted (P), Conditionally permitted (C), or Not permitted (–) in each district. If a use is present but not allowed today, it may be a nonconforming use and fall under § 10‑3.607 rules.

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