Redwood City — Nonconforming Uses

Last reviewed: July 2, 2026

Overview

This page explains how Redwood City’s Zoning Ordinance treats nonconforming lots, uses, structures and parking (Article 33) — what may continue, what must stop, and what changes require City approval. The summary below is built from the City's zoning ordinance provisions (especially Article 33) and the district articles that define where those rules apply. See the full rules on continuation, enlargement, abandonment, reconstruction after damage, and parking requirements in the ordinance (§33.1–§33.25) .

Important cross‑checks: anything that changes a building or use must also meet the City's development rules (see development standards) and parking rules, and must comply with the California Building Standards Code and local building/fire requirements (§33.23) .

How Article 33 works (core rules)

• Continuation: A lawful nonconforming use or structure may generally continue despite not meeting current zoning rules (see § 33.3) .
• Abandonment/Termination: If a nonconforming use ceases for a specified consecutive time it cannot be re‑established: 6 months for residential districts, 12 months for nonresidential districts, 6 months for mixed‑use districts, and 90 days for uses of land without significant structures (§ 33.8) .
• Expansion/Change: Expansion of a nonconforming use requires a Use Permit and special findings (must not create new adverse impacts, may preserve a historic resource, or be needed to meet legal requirements like disabled access) (§ 33.5, § 33.10) .
• Structural alteration: For residential structures, no more than 70% of existing exterior walls (linear feet) per residential unit may be removed/structurally altered within a rolling five‑year calculation unless the entire building is brought into compliance; same 70% rule applies to other structures (§ 33.11) .
• Damage/replacement: If a nonconforming structure is destroyed by a listed calamity, reconstruction is allowed to the same size if rebuilding commences within one year for conforming uses and nonconforming residential uses; for nonresidential nonconforming structures damaged more than 50% of current replacement cost, reconstruction must meet current standards (§ 33.12, § 33.15) .
• Parking: Nonconforming parking for residential uses has tailored rules (additions cannot reduce existing parking; new dwelling units must provide parking per Article 30) and nonresidential parking nonconformities can only be expanded with a Use Permit and additional findings (§ 33.16, § 33.19, Art. 30) .
• Interpretation and illegal uses: The Zoning Administrator can require a Use Permit where the article is unclear (§ 33.21) and the article does not legalize any illegal (never‑permitted) use (§ 33.22) .

A concise, decision‑focused summary table of the most relied‑on Article 33 rules appears below.

Key Article 33 standards (decision table)

District‑by‑district breakdown (where nonconformity rules are applied)

Article 33 applies across all zoning districts; below are the primary district entries and the local district articles that tell you what a "conforming" standard is in that district (so you can apply nonconforming rules correctly). For each district I name the Article that sets the purpose/standards and point to the most relevant numerics where the ordinance text is explicit.

Notes on links: where the district discussion touches site development controls, check the City's development standards and on‑site parking. For design changes review the City's design review rules and check overlay maps at overlay districts. For ADU‑related nonconforming accessory structures see the City ADU rules at ADUs. Major building/health compliance still falls under the California Building Standards Code and local building/fire review (per §33.23) .

R‑1 (Residential — Single‑Family)

• Purpose: Residential single‑family uses; standards are in Article 5 (see § 5.1–§ 5.9) .
• Typical permitted uses: single‑family dwelling, accessory structures, home occupations; ADUs governed by Article 37. See ADU page for how accessory nonconforming structures may be converted to ADUs (§33.11.D) .
• Key dimensional standards: lot area, coverage, setbacks and pervious area are set in Article 5 (check §5.x where your lot is located) — Article 5 is the controlling district article cited in the code table of contents .
• How Article 33 applies: Nonconforming residential uses/structures may continue but are subject to the 70% exterior wall rule for structural alterations and the 6‑month abandonment rule for residential nonconforming uses (§33.11, §33.8) . Verify setbacks and lot coverage using Article 5 before proposing changes.

R‑2 (Residential — Duplex)

• Purpose & uses: Article 6 defines permitted duplex and accessory uses and density limits; see Article 6 for setbacks, lot size and coverage (§6.1–§6.9) .
• Nonconforming treatment: Same core Article 33 rules — 70% structural alteration limit, 6‑month abandonment period for residential nonconforming uses, and special parking treatment in §33.16 for parking‑only nonconformities .

R‑3 / R‑4 / R‑5 (Multi‑family districts)

• Purpose & uses: Articles 8 (R‑3), 9 (R‑4), 10 (R‑5) contain permitted uses, permitted density, lot coverage, setbacks and pervious area rules (see the table of contents entries and district articles) .
• Nonconforming specifics: Multi‑family nonconforming structures follow the 70% structural alteration limit (§33.11) and the nonconforming parking rules for residential uses (§33.16) apply; replacement after damage rules also apply but note the one‑year rebuilding window for nonconforming residential uses (§33.11, §33.12, §33.16) .

CN (Neighborhood Commercial) — Article 13

• Purpose: Neighborhood‑scale commercial services serving nearby residents (§13.1). Key development standards (setbacks, lot coverage, FAR) are in Article 13. Examples: permitted uses table, side/rear yard rules and a maximum FAR of 40% (§13.12), minimum 10% pervious area (§13.13), side/rear yard specifics in §13.9 and additional rules for uses near R districts (§13.10) .
• How nonconforming rules interact: Article 13 explicitly allows certain pre‑existing office uses as legal nonconforming uses and states they may be remodeled without a use permit so long as floor area devoted to offices is not increased — this local exception controls over Article 33 in a conflict (§13.10) . For parking impacts and expansions, apply §33.19 and Art. 30 rules .

CB (Central Business) — Article 14

• Purpose & uses: Downtown/commercial core uses and mixed commercial uses; Article 14 contains permitted, accessory and conditional uses and yard/coverage rules (§14.1–§14.10) .
• Nonconforming treatment: Nonconforming downtown uses/structures follow Article 33. For changes that affect historic resources or public impacts, the Use Permit route under §33.5/§33.10 is commonly used; coordinate with downtown design review and the City's development standards when proposing enlargement (§33.5, §33.10) .

PO (Professional Office) — Article 11

• Purpose & uses: Office and professional services; Article 11 identifies permitted uses, conditional uses, and dimensional standards to be applied when assessing nonconformities (§11.1–§11.10) .
• Nonconforming issues: PO nonconforming uses that are listed as conditional remain nonconforming until a Use Permit is obtained (see §33.4). Structural change limits and replacement rules in Article 33 still apply (§33.4, §33.11, §33.12) .

IP / IR / GI (Industrial & Industrial Park) — Article 18 / 17 / 19

• Purpose & uses: Industrial‑type uses are in Articles 18 (IP) and 19 (GI) (and IR where applicable). Permitted uses (manufacturing, warehousing, research) and conditional uses are laid out in district text; nonconforming industrial uses are treated under Article 33 but note conditional/permit requirements for special industrial uses (§18.2, §19.1–19.2) .
• Practical point: Nonresidential (industrial/commercial) nonconforming structures damaged beyond 50% replacement cost face stricter reconstruction rules (§33.12.C) .

MUW / MUN / MUT (Mixed‑Use Waterfront / Neighborhood / Transitional) — Articles 57 / 54 / 55

• Purpose & uses: Mixed‑use districts have detailed building and site standards (height, frontage, sidewalk/setback rules, open space) that define what is "conforming" in those districts; see Articles 54–57 for specifics (e.g., Table 53‑2 for sidewalk/setback standards in the Mixed‑Use Corridor / neighborhood context) .
• Nonconforming application: Article 33 rules apply, but many mixed‑use articles require that new portions conform to district standards when enlarging a structure and may have overlay/design review requirements; coordinate with design review and any overlay rules at overlay districts when pursuing a Use Permit (§33.10, §33.21) .

PF (Public Facilities), MH (Mobile Home), TP (Tidal Plain), IS (Interim)

• Each special district (PF Art. 23, MH Art. 24, TP Art. 20, IS Art. 22) has its own permitted uses and standards; nonconforming uses within these districts follow the same Article 33 framework — check the particular district article for the local dimensional and use rules to determine conformity before applying Article 33 (§23.x, §24.x, §20.x, §22.x referenced in the table of contents) .

Practical guidance / how to approach a nonconforming project in Redwood City

1. Confirm whether the existing use or structure was lawful when created (Article 33 applies only to lawful nonconformities) — check permit history and prior code status (§33.3) .
2. Determine which district the parcel is in and pull the district article (e.g., Article 5 for R‑1, Article 13 for CN, Article 14 for CB) to identify the current dimensional standards you must meet for any enlargement (§33.10) .
3. If you plan enlargement, intensification, or structural alteration, test applicability of the 70% exterior‑wall rule (§33.11) and whether a Use Permit is required (§33.5, §33.10) .
4. For changes affecting parking, coordinate with Article 30 and the City’s parking rules; nonresidential parking nonconformities require a Use Permit with extra findings (§33.16, §33.19) .
5. If the structure was damaged, calculate current replacement cost and apply the 50% threshold for nonresidential structures and 1‑year rebuild deadlines for residential/nonresidential conditions (§33.12) .
6. Always verify building/fire code compliance (state and local) — Article 33 explicitly requires compliance with Building and Fire Department rules for any change (§33.23) and check the California Building Standards Code for technical standards (§33.23) .
7. If unclear, request a written interpretation from the Community Development Director or Zoning Administrator (Article 41 tools and §33.21 interpretation authority) .

Checklist

• Confirm the use/structure was lawful when established (no unlawful/illegal uses are protected) — § 33.3, § 33.22
• Identify the zoning district and pull the district Article (e.g., Art. 5, 6, 8, 13, 14 as applicable) to know current setbacks/FAR/coverage — see table of contents entries for district Articles
• Determine if the proposal is an enlargement, structural alteration, or change of use (If enlargement or expansion → Use Permit likely required) — § 33.5, § 33.10
• For structural alterations, calculate removal of exterior wall linear feet against the 70% limit (per unit) (§ 33.11)
• For parking changes, confirm compliance with Article 30 and whether the project reduces existing parking (§ 33.16, § 33.19)
• If damaged/demolished, compute replacement cost % and check rebuild timelines (1 year) and thresholds (50% for nonresidential) (§ 33.12)
• Ensure Building & Fire Department requirements are addressed and budget for required corrections (§ 33.23)
• If uncertainty remains about interpretation, request a written interpretation from the Director or Zoning Administrator (§ 33.21, Art. 41)

Risks & Ambiguities

Plain‑English summary

If your property in Redwood City was legally built or used under older rules, Article 33 generally lets that use or building continue, but the City limits enlargements, imposes time limits for re‑establishing abandoned uses, caps large structural changes (the 70% wall rule), and controls reconstruction after damage; many changes will require a Use Permit, and all changes must meet building and fire rules (§33.1–§33.25) .

Information Gaps

• Exact numeric setback, height, coverage and floor‑area ratio standards for every district parcel are not reproduced in full here — confirm the specific district Article for a parcel (e.g., Art. 5 for R‑1, Art. 13 for CN, Art. 14 for CB) because only those articles list the precise dimensional standards (setbacks, lot area, coverage) required to evaluate conformity. See district articles referenced in the table of contents .
• Parcel‑specific historic approvals, recorded conditions, or prior Use Permits that may create vested rights are not in these ordinance extracts; these require City record checks ("Verify with the jurisdiction") (see Art. 41 permit continuity notes) .
• Exact administrative filing fees, submittal requirements and technical checklist items (e.g., required engineering reports to show replacement cost) are not in Article 33 text and must be confirmed with Community Development / Building permitting staff. Article 33 requires coordination with Building/Fire departments but does not publish department checklists on these pages (§33.23) .

Source References

• Redwood City Zoning Ordinance, Article 33, "Nonconforming Lots, Uses, Structures and Parking" (Table of contents and §33.1–§33.25) — see §33.1, §33.2, §33.3, §33.4, §33.5, §33.8, §33.9, §33.10, §33.11, §33.12, §33.16, §33.19, §33.21, §33.22, §33.23, §33.24, §33.25.
• CN (Neighborhood Commercial) District — §§13.1–13.13 (purpose, yards, FAR, pervious area) — see §13.9, §13.10, §13.12, §13.13.
• CB (Central Business) District — §§14.1–14.10 (uses and conditional uses).
• PO (Professional Office) District — Articles 11 and related use/yard rules.
• IP / GI Districts (Industrial) — Articles 18 and 19 (permitted uses and purpose).
• Mixed‑Use Districts (MUN / MUT / MUW) — Articles 54–57 and sidewalk/setback tables (see Table 53‑2 references).
• Zoning ordinance table of contents and district index (showing Article numbers referenced above).

Retrieved passages

• Redwood City Zoning Code (§ 4) High relevance show source text
• Redwood City Zoning Code (Section 42.3) High relevance show source text
• Redwood City Zoning Code (§ 18) High relevance show source text
• Redwood City Zoning Code (§ 18) High relevance show source text
• Redwood City Zoning Code (article to) High relevance show source text
• Redwood City Zoning Code (article shall) High relevance show source text
• Redwood City Zoning Code (§ 18) High relevance show source text
• Redwood City Zoning Code (§ 4) High relevance show source text
• Redwood City Zoning Code (§ 18) High relevance show source text
• Redwood City Zoning Code Medium relevance show source text
• Redwood City Zoning Code Medium relevance show source text
• Redwood City Zoning Code Medium relevance show source text
• Redwood City Zoning Code (Article 1) Medium relevance show source text
• Redwood City Zoning Code Medium relevance show source text
• Redwood City Zoning Code (§ 2.21.2) Medium relevance show source text
• Redwood City Zoning Code (section ceases) Medium relevance show source text
• Redwood City Zoning Code (Article 33) Medium relevance show source text

Cited sections

• Redwood City Zoning Ordinance, Article **33**, "Nonconforming Lots, Uses, Structures and Parking" (Table of contents and §33.1–§33.25) — see §33.1, §33.2, §33.3, §33.4, §33.5, §33.8, §33.9, §33.10, §33.11, §33.12, §33.16, §33.19, §33.21, §33.22, §33.23, §33.24, §33.25. fileciteturn1file1fileciteturn1file0 (§33.1)
• CN (Neighborhood Commercial) District — §§13.1–13.13 (purpose, yards, FAR, pervious area) — see §13.9, §13.10, §13.12, §13.13. fileciteturn2file5 (§13.1)
• CB (Central Business) District — §§14.1–14.10 (uses and conditional uses). fileciteturn2file2 (§14.1)
• PO (Professional Office) District — Articles **11** and related use/yard rules.
• IP / GI Districts (Industrial) — Articles **18** and **19** (permitted uses and purpose). fileciteturn2file17
• Mixed‑Use Districts (MUN / MUT / MUW) — Articles **54–57** and sidewalk/setback tables (see Table 53‑2 references). fileciteturn2file13
• Zoning ordinance table of contents and district index (showing Article numbers referenced above). (Article numbers)
• RedwoodCity_ZoningCode.md

• Official Redwood City code library