South San Francisco — Nonconforming Uses

Last reviewed: July 2, 2026

Overview

This page explains how South San Francisco regulates nonconforming uses, nonconforming structures, and nonconforming lots under the City’s zoning ordinance (commonly Title 20). The rules are citywide but include targeted exceptions and procedures in specific districts (Downtown, Oyster Point, Genentech, transect/form-based and specific-plan districts). All rules below are grounded in the Zoning Ordinance; citations point to the controlling § and the city code excerpts retrieved.

Note: links below point to related topics in the city menu where the ordinance refers to them — e.g., when you see parking, development standards, or design review they link to the city pages indicated.

How South San Francisco defines and treats nonconformities (citywide)

• Lawful pre-existing uses, structures, or lots that do not comply with the ordinance on its effective date (or any later amendment) are treated as nonconforming and may continue only under the limitations in Chapter 20.320. The defining text appears in § 20.320.002.

• A nonconformity can be triggered by many different inconsistencies (location, density, floor area, height, yard, buffering, or lack of required permits), but a use or structure is not made nonconforming solely for failing to meet some parking dimension or other narrow technical parking/loading/planting standards (see cross-reference to on-site parking). § 20.320.002(A) and cross-reference to § 20.330.003(B).

• The right to continue a lawful nonconforming use attaches to the land and survives changes in ownership, provided the nonconforming use or structure is not altered, enlarged, increased in occupant load, or otherwise intensified except as allowed in Chapter 20.320. § 20.320.002(B).

• Basic prohibitions and permissions:

  • No expansion of a nonconforming use is allowed except where the Code provides (nonconforming uses shall not be expanded). § 20.320.006.
  • Repairs and maintenance are allowed so long as they do not enlarge or extend the structure (see § 20.320.003 and § 20.320.004 for limitations and when a Minor Use Permit or Variance is required).
  • If damaged, rebuilding is governed by a 50% appraised-value threshold: if repair/reconstruction cost is ≤ 50 percent of appraised value, replacement to the same size/extent/configuration is allowed; if > 50 percent, the property must comply with the ordinance unless the Chief Planner approves a Minor Use Permit (special rules for residential buildings require a Minor Use Permit and parking/unit-count limits). § 20.320.007.
  • Abandonment: a nonconforming use that ceases for a continuous period of one year is considered abandoned (with limited exceptions for residential uses and some discretionary extensions outside core downtown districts). § 20.320.008.

• Substitution or change of a nonconforming use to another use requires a Use Permit unless the new use is permitted by right; the Chief Planner may permit substitution of one nonconforming use for another only after specific findings and conditions (traffic/compatibility/General Plan consistency, etc.). § 20.320.005.

• Nonconforming lots that pre‑date the ordinance may still be used as building sites if they are recorded lots of record, subject to compliance with applicable standards or an approved Variance. § 20.320.002(C).

District-by-district notes (where the ordinance creates district-specific implications)

The nonconforming chapter is citywide, but several district chapters and plan districts include special standards or call out nonconforming treatment; below are the districts where South San Francisco’s ordinance places decision‑relevant distinctions. Each district subsection lists the district purpose (as the ordinance states), typical permitted uses, key dimensional standards cited in the ordinance, and where the district applies.

Downtown Residential (DRL / DRM / DRH)

• Purpose: support residential character and manage compatible mixed uses in the downtown residential core. § 20.080.001—.003 describes intent and development standards.
• Typical permitted uses: residential (single- and multi-family), home occupations, some accessory uses per Chapter 20.350; permit levels are shown in Table 20.080.002. § 20.080.002.
• Key dimensional standards (representative): front setbacks, interior side and rear setbacks, min. usable open space 100 sf/unit, and upper-story step-back rules; see Table 20.080.003 for specifics. § 20.080.003.
• Nonconforming implications: the City treats residential uses as protected from lapse (no lawful residential use can lapse regardless of length of non‑use) under the abandonment rules in § 20.320.008(A)(1).

Downtown / Caltrain Station Area (DRC, LNC, GAC, DTC, ETC)

• Purpose: revitalize Downtown and areas around Caltrain, encourage transit‑oriented higher intensity uses. § 20.090.001.
• Typical permitted uses and permit levels: listed in Table 20.090.002 (multifamily, retail, offices, civic uses; the table shows P/M/C by subzone such as DRC, LNC, GAC, DTC, ETC). § 20.090.002 and Table 20.090.002.
• Key dimensional standards (representative): minimum lot area 5,000 sf (typical), FAR ranges by subdistrict (e.g., 0.5–8.0 with higher FARs tied to community benefits), and building heights up to 85 ft in some subareas (see Table 20.090.003). § 20.090.002 and Table 20.090.003.
• Nonconforming implications: Downtown subdistricts have special treatment for allowable extensions of substandard side/rear setbacks and demolition/rehabilitation within overlays; abandonment extensions that apply outside Downtown typically do not apply here (see § 20.320.008 exceptions). § 20.320.004(E) and § 20.320.008.

Oyster Point Specific Plan (OPSP)

• Purpose and area: sets district standards for Oyster Point development. See Table 20.230.004(1) for development standards. § 20.230.004.
• Typical permitted uses: mixed-use programs, offices, hotel, and other area‑specific uses with FAR caps by planning area (e.g., FAR 0.5–1.6 depending on use/area and incentives). Table 20.230.004(1).
• Nonconforming implications: lots or buildings that cease qualifying for the OPSP are treated as nonconforming if they existed at time of removal and are not hazardous; Reconstruction is allowed to the prior nonconforming extent but no expansion beyond the pre‑damage footprint. § 20.260.005 (removal from Genentech Master Plan District provides an analogous approach for plan district removals).

Genentech Master Plan District (campus-specific)

• Purpose: campus master plan rules and conditions for removal or changes of lot status are in the Genentech chapter. § 20.260.005 explains that properties removed from the Master Plan District may be treated as nonconforming and permitted to continue prior lawful uses but cannot expand nonconformities. § 20.260.005.
• Typical permitted uses: campus, R&D, institutional and related uses as set in the Genentech Master Plan (see chapter text for detailed use lists). § 20.260 chapters.

Form‑based / Transect and Specific Plan Districts (T3N, T3ML, T4L, Southline S‑C, Lindenville)

• Purpose: these districts use form-based controls; allowed uses/tables are in Chapter 20.135 (Transect Zones) and in each Specific Plan (e.g., Southline S‑C § 20.290). § 20.135.020 and § 20.290.004–.005.
• Typical permitted uses: mixed (makers, residential, light industrial, retail) by transect. Table 20.135.060.B.1 lists use permissions. § 20.135.060.
• Nonconforming implications: where a Specific Plan or transect district lacks a specific rule, Chapter 20.320 applies; several Specific Plan chapters explicitly point to Chapter 20.320 for nonconforming treatment. § 20.290.004 and related specific-plan provisions.

Quick Reference Table — Most decision‑relevant nonconforming rules

Practical guidance / plain‑English synthesis

• If you own or represent a pre‑existing use or building that predates the current zoning map, you generally may keep operating it, but you cannot enlarge the nonconforming portion or increase intensity without entitlements. See § 20.320.002(B) and § 20.320.006.

• Small maintenance and interior repairs are routine; structural additions that change setbacks, height, or coverage usually require a discretionary approval (Minor Use Permit or Variance) and findings showing no harm to neighbors or plan inconsistency. See § 20.320.003—.004 and Chapter 20.500 (Variances) for procedures.

• If your project triggers parking changes, consult the City’s on‑site parking rules: the Code explicitly excludes some parking technicalities from nonconforming status but requires compliance where additions create new parking demand — see § 20.320.002(A) and Chapter 20.330 on parking. For parking rules see the City’s parking page. (See parking) § 20.320.002(A).

• For accessory dwelling units (ADUs), the ordinance allows ADUs on lots with a nonconforming primary dwelling subject to state law and local ADU chapter conditions; if the primary unit is nonconforming due to parking, the ADU may still be developed if parking for the primary unit is provided to meet Chapter 20.330 standards (flexible configurations allowed). § 20.320.004(C) and § 20.350.003.

• When a nonconforming property has been substantially damaged, the 50% rule is critical: confirm the City’s appraised value method and whether the Chief Planner can approve a Minor Use Permit to restore the prior configuration. § 20.320.007.

(First instances of related topics linked: parking, development standards, design review, overlay districts, ADUs, California Building Standards Code, variances — follow those links for detail.)

• parking: South San Francisco Parking
• development standards: South San Francisco Development Standards
• design review: South San Francisco Design Review
• overlay districts: South San Francisco Overlay Districts
• ADUs: South San Francisco ADUs
• California Building Standards Code: California Building Standards Code
• variances: South San Francisco Variances and Exceptions

Checklist — what an applicant must typically provide or satisfy

• Proof the use/structure/lot was lawfully established (business licenses, prior permits, historic occupancy records) to meet the legal nonconforming claim (responsibility of applicant). § 20.320.008.
• Site plan and narrative showing no increase in area/occupant load/intensity of the nonconforming use (or justification and required applications if changes are sought). § 20.320.002(B).
• If making additions that affect yards or heights, a Minor Use Permit application with findings (and design review if required). § 20.320.004(D) and Chapter 20.480.
• If repairs exceed 50% of appraised value after damage, an appraisal and a demonstration of compliance or Minor Use Permit application per § 20.320.007.
• Parking and loading analysis if change/substitution increases trips — include a Parking Management and Monitoring Study where required by § 20.320.005 and Chapter 20.330. (See parking)
• Evidence resisting abandonment if the use was temporarily inactive (documentation of lease, utilities, business license, or other proof). § 20.320.008.

Risks & Ambiguities

Plain‑English Summary

If your building, use, or lot in South San Francisco was lawful before the current Zoning Ordinance, you generally may keep using it as it existed, but you cannot increase its size or intensity without City approval; major repairs after damage and changes of use have specific thresholds and permit routes you must follow. For exact rules see the nonconforming chapter (Chapter 20.320) and the district rules that apply to your site. § 20.320.001—.008.

Source References

• South San Francisco Zoning Ordinance, Chapter 20.320, Nonconforming Uses, Structures, and Lots — § 20.320.001—§ 20.320.008.
• South San Francisco Zoning — Continuation, Maintenance, Alterations and Abandonment rules referenced in § 20.320.002, § 20.320.003, § 20.320.004, § 20.320.005, § 20.320.006, § 20.320.007, § 20.320.008.
• Downtown/Caltrain Station Area Districts: § 20.090.001—.003 and Tables 20.090.002/20.090.003 (uses, FAR, heights) — excerpted sections.
• Downtown Residential District standards and Table 20.080.003 (development standards) — § 20.080.002—.003.
• Oyster Point Specific Plan District, Table 20.230.004(1) development standards. § 20.230.004.
• Genentech Master Plan District removal and nonconforming provisions: § 20.260.005.
• Transect/form‑based districts and Specific Plans: Chapters 20.135 and 20.290 (use tables and cross‑references to Chapter 20.320).

External copy of the municipal code where these sections are published (source used to compile content): https://ecode360.com/SO5016 (downloaded copy referenced in retrieved materials).

Retrieved passages

• South San Francisco Zoning Code (chapter apply) High relevance show source text
• South San Francisco Zoning Code (§ 2) High relevance show source text
• South San Francisco Zoning Code (§ 2) High relevance show source text
• South San Francisco Zoning Code (Chapter 20.360) High relevance show source text
• South San Francisco Zoning Code (Chapter 20.490) High relevance show source text
• South San Francisco Zoning Code (§ 2) High relevance show source text
• South San Francisco Zoning Code (§ 20.320.005) High relevance show source text
• South San Francisco Zoning Code (Section 20.330.003) High relevance show source text
• South San Francisco Zoning Code (§ 20.260.005) High relevance show source text
• South San Francisco Zoning Code (§ 20.260.003) Medium relevance show source text
• South San Francisco Zoning Code (§ 20.090.003) Medium relevance show source text
• South San Francisco Zoning Code (Chapter 20.350) Medium relevance show source text
• South San Francisco Zoning Code (§ 20.100.003) Medium relevance show source text
• South San Francisco Zoning Code (§ 20.090.002) Medium relevance show source text
• South San Francisco Zoning Code (Chapter 20.490) Medium relevance show source text
• South San Francisco Zoning Code (§ 20.135.060) Medium relevance show source text

Cited sections

• South San Francisco Zoning Ordinance, Chapter 20.320, Nonconforming Uses, Structures, and Lots — **§ 20.320.001—§ 20.320.008**. (Chapter 20.320)
• South San Francisco Zoning — Continuation, Maintenance, Alterations and Abandonment rules referenced in **§ 20.320.002**, **§ 20.320.003**, **§ 20.320.004**, **§ 20.320.005**, **§ 20.320.006**, **§ 20.320.007**, **§ 20.320.008**. (§ 20.320.002)
• Downtown/Caltrain Station Area Districts: **§ 20.090.001—.003** and Tables 20.090.002/20.090.003 (uses, FAR, heights) — excerpted sections. (§ 20.090.001)
• Downtown Residential District standards and Table 20.080.003 (development standards) — **§ 20.080.002—.003**. (§ 20.080.002)
• Oyster Point Specific Plan District, Table 20.230.004(1) development standards. **§ 20.230.004**. (§ 20.230.004)
• Genentech Master Plan District removal and nonconforming provisions: **§ 20.260.005**. (§ 20.260.005)
• Transect/form‑based districts and Specific Plans: Chapters 20.135 and 20.290 (use tables and cross‑references to Chapter 20.320). (Chapter 20.320)
• SouthSanFrancisco_ZoningCode.md

• Official South San Francisco code library