Local zoning · San Francisco County

San Francisco County — Nonconforming Uses

Q: How long can a nonconforming use be unused before it’s considered abandoned?

As a general rule, 3 years of continuous discontinuance results in loss of nonconforming status; for uses without an enclosed building, 6 months can be abandonment. Some uses (e.g., Formula Retail) and some neighborhood districts have shorter 18‑month or other special periods. See § 183 . § 183

Q: Do limited commercial uses in residential districts get any special protection?

Yes — § 186 provides for the continued operation of small, neighborhood-serving commercial/industrial uses in RH , RM , RTO , and RED districts if they meet the first-story/size/use limitations (often tied to NC-1 first-story rules). § 186

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

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Last reviewed: July 3, 2026

Overview

This reference explains how the San Francisco Planning Code treats nonconforming uses, noncomplying structures, and substandard lots of record for properties in the unincorporated areas of San Francisco County. It is a focused synthesis of the Planning Code rules (primarily Article 1.7) that control whether an existing use or building that no longer matches current zoning may continue, be changed, or must be eliminated. Key controlling provisions include § 180, § 181, § 182, § 183, § 184, and § 186 of the Planning Code.

What the Code requires (top-line rules)

A lawful use or structure that predates a zoning change may continue as a nonconforming use or noncomplying structure but is subject to the limitations in § 180 (definitions and general rules) and the rest of Article 1.7. § 180
Enlargement or intensification of a nonconforming use is generally prohibited: a nonconforming use or the structure containing it “shall not be enlarged, intensified, extended, or moved,” except where the enlargement results in elimination of nonconformity or specific exceptions apply. § 181(a)
Ordinary maintenance and limited repairs are allowed; alterations that expand the portion occupied by the nonconforming use are not, except as the Code specifically permits. § 181(b)
A nonconforming use may be changed to a permitted principal use of the district; once converted, the nonconforming status cannot be restored. § 182(d–f)
Discontinuance / Abandonment: generally a continuous discontinuance of three years ends nonconforming status (six months for uses without an enclosed building). Formula Retail and some neighborhood exceptions have different timeframes (e.g., 18 months for Formula Retail in certain districts). § 183
Certain small neighborhood commercial or industrial nonconforming uses in residential districts may receive special treatment/exemptions from termination under § 186 (the “Limited Commercial/Industrial” exemptions in RH, RM, RTO, and RED districts). § 186
Special rules govern nonconforming signs and awnings (including temporary amnesty programs) — see § 187.3 for recent amnesty language. § 187.3

If you need the text of the referenced provisions, start with § 180 and the immediately following sections of Article 1.7.

District-by-district breakdown (how rules interact with major districts)

Note: below, district names are the Planning Code districts; these rules apply to properties in the unincorporated areas of San Francisco County in the corresponding district shown on the zoning map (verify the zoning map for a specific parcel). For definitions of the district groupings (e.g., what counts as an R District or PDR District), consult the Code’s district definitions. § 201 and the district-definition list.

RH District (e.g., RH-1, RH-2, RH-3)

Purpose: predominantly residential with allowance for limited neighborhood-serving commercial uses in constrained forms. See Code grouping “RH District.” § 231, § 186
Typical permitted uses: dwellings, Live/Work in some circumstances, limited corner retail (subject to use size limits). § 231 describes corner retail size and location limits. § 231(d)
Key dimensional/operational limits relevant to nonconforming uses: neighborhood exemptions in § 186 allow some limited commercial nonconforming uses to remain if they meet the small-scale/first-story limitations (i.e., conforming to NC-1 first-story use rules). § 186(a)(1–2)
Where it applies: residential neighborhoods (see zoning map). Verify distance-to-restricted-subdistrict rules in § 186 for exemption eligibility. § 186

RM District (e.g., RM-1 — RM-4)

Purpose: medium- to higher-density residential; allows group housing and some ground-floor commercial in parts. See the RM Zoning Control Table for building standards. Table 209.2 / § 209.2
Typical permitted uses: multiple dwelling units, live/work units, limited first-story retail in some locations. § 209.2
Nonconforming implications: limited commercial nonconforming uses can be exempt from termination under § 186 if they meet the size and location rules and the first-story NC-1 use limitations. § 186
Key standards: front/rear setback, rear-yard percentages, and height/bulk limits are in the RM tables and referenced sections; substandard lots can nonetheless carry the same dwelling entitlement as standard lots under § 180 Interpretations. Table 209.2; § 180 interpretation

RTO District (e.g., RTO-1, RTO-M)

Purpose: residential-technology-office mixes and transitional residential districts; limited ground-floor commercial is often regulated to preserve residential character. § 231 and § 186 describe corner commercial and exemptions. § 231
Nonconforming uses: subject to the same enlargement/intensification prohibitions in § 181; limited corner-commercial nonconforming uses may continue if they meet the size/use rules in § 231 and § 186. § 181; § 231; § 186

Neighborhood Commercial Districts (NC-1, NC-2, NCT, etc.)

Purpose: pedestrian-oriented commercial corridors (standards vary by NC subtype). Use limitations for first story play a central role in whether a limited commercial nonconforming use in an adjacent R District can be continued. See § 710 (NC first-story limitations referenced elsewhere). § 710; § 186
Nonconforming uses: a nonconforming commercial use that relocates or intensifies in a Neighborhood Commercial District can trigger Conditional Use or other review per § 182 and Article 3 procedures. § 182

PDR Districts (PDR-1-B, PDR-1-D, PDR-1-G, PDR-2)

Purpose: retain and encourage production, distribution, and repair uses; protect industrial capacity and large flexible spaces. § 210.3 / § 202.7 / § 202.8
Typical permitted uses: light industrial, manufacturing, design studios, compatible small-scale retail/office in some subdistricts. § 210.3
Nonconforming uses: PDR conversions are tightly regulated; replacement-space and conversion limits are imposed to protect PDR stock (see § 202.7 and § 202.8). These provisions limit when a PDR nonconforming use may be lost through conversion and impose replacement requirements for demolition. § 202.7; § 202.8

C-3 Districts (downtown/commercial cores: C-3-O, C-3-R, C-3-G)

Purpose: downtown/commercial with higher intensity; certain permanent nonconforming parking lots were treated specially in older code language (see § 184). § 184
Nonconforming uses: high-intensity changes that enlarge nonconformity are treated under § 181 and discontinuance rules § 183; elderly grandfathered parking-lot nonconformities were historically time-limited per § 184. § 181; § 183; § 184

Key Code excerpt table (decision‑relevant rules)

Rule / Permitted action	What the applicant can do	Code Reference
Continue an existing lawful NCU	May be continued subject to Article 1.7 limits	§ 180
Enlarge or intensify an NCU	Generally prohibited (except narrow exceptions)	§ 181(a–b)
Change NCU to conforming principal use	Allowed; once changed, cannot revert to former NCU	§ 182(d–f)
Discontinue/Abandonment timeframe	3 years continuous discontinuance (6 months if no enclosed building); special 18‑month rules for Formula Retail/selected NC districts	§ 183
Limited commercial in R Districts	May be exempt from termination if meeting small-scale and location limits (NC-1 first-story limits)	§ 186(a–b)
Nonconforming sign/awning amnesty	Certain existing signs/awnings may be treated as NCUs under limited amnesty rules	§ 187.3

Practical guidance & interpretations (plain-English but code‑grounded)

To preserve a nonconforming dwelling unit where records are unclear, the Code presumes the unit is a legal nonconforming unit unless the administrative record proves otherwise (presumption favors continuance). § 180(h)
“Significant” enlargements or intensifications (which trigger Conditional Use review or prohibition) are interpreted with specific numerical examples in Zoning Administrator guidance: expansions > 25% of floor area or > 500 sq ft are typically treated as significant. Interpretations are in Planning Department rulings (see interpretations to § 181/§ 186.1). § 186.1 interpretations
Changing an NCU to residential (converting a nonconforming commercial space to dwelling units) is allowed in many districts, sometimes via Conditional Use authorization and with relief from certain standards where the Code authorizes it — but the conversion must eliminate the nonconforming use and comply with Building Code/Housing Code requirements. § 182(e)
If you plan to relocate a nonconforming use within a Neighborhood Commercial District, expect a new Conditional Use review and deed restrictions for the old premises in many instances. § 182(e)

Inline note about related approvals and standards: nonconforming-use questions commonly touch parking (off-street parking rules), design review, overlay districts, and ADU rules — consult those topics in the County menu when preparing an application: San Francisco County Parking, San Francisco County Design Review, San Francisco County Overlay Districts, and state ADU constraints via California ADU law. If structural or life-safety work is needed for the project, consult the California Building Standards Code (Title 24) — but building-code compliance is a separate review (not covered here).

Checklist

Determine whether the existing use/structure was lawfully established and gather permits/records to prove lawful use (title/permits/occupancy). § 180(e)
Confirm whether the use is a nonconforming use or the building a noncomplying structure under § 180 definitions. § 180(a–c)
If proposing a change, verify whether the change would be an enlargement/intensification (prohibited) — consult the Zoning Administrator interpretations for “significant.” § 181; interpretations
If converting NCU to a permitted conforming use (e.g., residential), prepare any Conditional Use application or Zoning Administrator approvals required by § 182. § 182(e)
Check discontinuance/abandonment history (has the use been discontinued > 3 years or, for certain uses, 18 months?). § 183
If the parcel is in a PDR or other special district, confirm conversion/replacement-space obligations under § 202.7 / § 202.8. § 202.7; § 202.8
For signs/awnings, confirm whether the amnesty in § 187.3 or other sign rules apply. § 187.3

Risks & Ambiguities

Issue	Why it matters	What to verify
“Significant” enlargement/intensification	Triggers Conditional Use or prohibition; ambiguous term in code	Review Zoning Administrator interpretations (examples: >25% or >500 sq ft) and get a pre-application determination. § 181; § 186.1 interpretations
Whether a use was “lawfully established”	Establishment date/permit history controls whether a use is protected	Collect permits, historical occupancy certificates, tax/assessor records; presumption favors continuance for dwellings when record is inconclusive. § 180(e), (h)
Conversion in PDR Districts	Special replacement-space and conversion limits may require replacement or limit conversion	Confirm whether the site falls in the Eastern Neighborhoods PDR conversion rules and any exemptions. § 202.7; § 202.8
Formula Retail rules	Formula Retail NCUs have special abandonment/relocation rules (18 months)	Confirm Formula Retail status and applicable restricted subdistricts. § 182(g); § 183(b)
Whether contiguous lots are treated as a single zoning lot	Affects calculation of density, open space, and whether a structure relied on another lot	Zoning Administrator practice: contiguous lots are not merged unless treated as a single lot historically or by merger; verify with the Zoning Administrator. (Interpretation to § 181)
Overlay / restricted use subdistricts	Can impose extra limits or different discontinuance periods	Check overlay/subdistrict boundaries (e.g., Restricted Use Subdistricts referenced in § 186) and the specific subdistrict ordinance text. § 186

Plain-English Summary

If a use or building on a parcel in the unincorporated areas became nonconforming because the zoning later changed, the Planning Code generally lets it continue but does not let you expand or intensify it; long-term vacancy or a change of use to a permitted use can end that protection. The controlling rules are in Article 1.7—mainly § 180–§ 186—and there are special protections and limits for small neighborhood commercial uses and PDR conversions. § 180–186

Source References

Planning Code, § 180 — Nonconforming uses, noncomplying structures, substandard lots (general definitions & rules). § 180
Planning Code, § 181 — Nonconforming uses: enlargements, alterations, reconstruction (limits on intensification). § 181
Planning Code, § 182 — Nonconforming uses: changes of use (conversions to conforming uses; Formula Retail rules). § 182
Planning Code, § 183 — Discontinuance and abandonment rules (timeframes: 3 years; 6 months for unenclosed uses; 18 months for certain Formula Retail cases). § 183
Planning Code, § 184 — Short-term continuance of certain nonconforming uses (historical parking-lot rules and time limits). § 184
Planning Code, § 186 — Exemption of limited commercial/industrial nonconforming uses in RH, RM, RTO, and RED Districts (conditions to continue). § 186
Planning Code, § 187.3 — Pre-existing awnings, gates, and signs; amnesty rules for certain noncomplying signs. § 187.3
PDR and conversion rules: § 202.7; § 202.8 (PDR replacement-space & conversion limits). § 202.7; § 202.8
RM district table and building standards reference: Table 209.2 / § 209.2 (RM districts). § 209.2
District-group definitions (what counts as an R/M/PDR/C-3 District): Planning Code district definitions. § 201 and district list.

Additional guides (planning / procedural topics referenced above):

San Francisco County Zoning overview: San Francisco County Zoning
Development standards and technical rules: San Francisco County Development Standards
Parking rules: San Francisco County Parking
Design review: San Francisco County Design Review
Overlay districts and special subdistricts: San Francisco County Overlay Districts
Signage and awning programs: San Francisco County Signage
Variances and exceptions procedures (if you need dimensional relief): San Francisco County Variances and Exceptions
ADU-specific state rules (when a nonconforming condition interacts with ADU permitting): California ADU law and California Building Standards Code for Title 24 considerations.

If a particular parcel or proposal raises questions about historic interpretations, zoning-lot mergers, or the meaning of “significant” enlargement, request a pre-application meeting with the Planning Department and ask for a Zoning Administrator determination — many edge cases are resolved through those interpretations. Verify parcel-specific status with the jurisdiction.

Sources

Retrieved passages

San Francisco County Zoning Code (Section 180.) High relevance
CBC § 307 (Section 307) High relevance
San Francisco County Zoning Code (Article 1.7.) High relevance
San Francisco County Zoning Code (Article 1.7.) High relevance
San Francisco County Zoning Code (section amended) High relevance
San Francisco County Zoning Code (Section 312) High relevance
San Francisco County Zoning Code (Section states) High relevance
San Francisco County Zoning Code (Section regulates) High relevance
San Francisco County Zoning Code (Section 186) High relevance
San Francisco County Zoning Code (Section and) Medium relevance
San Francisco County Zoning Code (Section 202.8) Medium relevance
San Francisco County Zoning Code (Section 308.2) Medium relevance
San Francisco County Zoning Code (Section 151.1) Medium relevance
San Francisco County Zoning Code (section by) Medium relevance
San Francisco County Zoning Code Medium relevance
San Francisco County Zoning Code Medium relevance

Cited sections

Official San Francisco County code library

Frequently asked questions

What is a nonconforming use in San Francisco County?

A nonconforming use is a lawful use that existed before a zoning change that now makes the use inconsistent with current zoning rules; it may continue subject to Article 1.7. See § 180 for definitions and general continuance rules. § 180

Can I enlarge or intensify a nonconforming use in the unincorporated areas?

Generally no — the Code bars enlargement, intensification, extension, or moving of a nonconforming use except where an alteration eliminates the nonconformity or specific exceptions apply. Check § 181(a–b) for these limits and permitted minor maintenance. § 181

How long can a nonconforming use be unused before it’s considered abandoned?

As a general rule, 3 years of continuous discontinuance results in loss of nonconforming status; for uses without an enclosed building, 6 months can be abandonment. Some uses (e.g., Formula Retail) and some neighborhood districts have shorter 18‑month or other special periods. See § 183. § 183

Can I convert a nonconforming commercial space to housing?

Yes — conversion of a nonconforming use to a permitted residential use is allowed and may be authorized (sometimes via Conditional Use) provided the conversion eliminates the nonconforming use and complies with relevant Code and Building/Housing standards. See § 182(e). § 182

Do limited commercial uses in residential districts get any special protection?

Yes — § 186 provides for the continued operation of small, neighborhood-serving commercial/industrial uses in RH, RM, RTO, and RED districts if they meet the first-story/size/use limitations (often tied to NC-1 first-story rules). § 186

If my nonconforming sign or awning was installed without a permit, can it stay?

Certain awnings, gates, and signs in existing non-residential businesses may be treated as noncomplying structures/nonconforming uses under an amnesty program and permitted to remain under § 187.3, subject to conditions. § 187.3

Do PDR districts have special rules about losing industrial uses?

Yes. Demolition or conversion of industrial (PDR) buildings and space triggers replacement-space and conversion limits intended to preserve PDR capacity; see § 202.7 and § 202.8 for requirements and exemptions. § 202.7; § 202.8

How is “significant” expansion defined for nonconforming uses?

“Significant” is an interpretive term but Zoning Administrator interpretations give examples (expansions over 25% of floor area or >500 sq ft are commonly treated as significant); consult departmental interpretations tied to § 181/§ 186.1. § 186.1 interpretations

If I change ownership, does nonconforming status end?

No. A simple change in ownership does not terminate nonconforming status unless the new owner takes action inconsistent with the Code; the status can continue under § 180(d). § 180(d)

Can a nonconforming use relocate within a Neighborhood Commercial District?

Relocation within a Neighborhood Commercial District requires approval as a new conditional use in many cases, and the Code requires deed restrictions and coordination to prevent immediate re-occupation of the original premises by the same use. See § 182(e). § 182

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