San Carlos — Zoning

Last reviewed: July 2, 2026

Overview

San Carlos implements zoning through the San Carlos Zoning Ordinance (Title 18), which establishes base and overlay districts, development standards, and the official Zoning Map maintained by the City Clerk. The ordinance organizes rules into Articles for base/overlay districts (Article II), general regulations (Article III), and administration (Article IV); the Official Zoning Map and rules for uncertain boundaries are set out in § 18.01.080.

This reference focuses strictly on what Title 18 says about zoning: district names and purposes, where the rules live, key standards that the ordinance explicitly provides, and the formal processes for map or district changes.

For broader context about how zoning interacts with other approvals (design review, parking, ADUs, and the California building code), see the city menu links below as they are referenced in-line as you read:

• San Carlos zoning & planning overview
• San Carlos Land Use
• San Carlos Development Standards
• San Carlos Parking
• San Carlos Design Review
• San Carlos Overlay Districts
• San Carlos ADUs
• California Building Standards Code

(Each of the eight link targets above is the first natural mention of that topic in this page.)

How Title 18 is organized (quick reference)

• Title name and purpose: § 18.01.010 and § 18.01.020 (Title 18 is the "San Carlos Zoning Ordinance" and is intended to implement the General Plan).
• Official Zoning Map and boundary rules: § 18.01.080 (map maintained by City Clerk; rules for ambiguous boundaries provided).
• Article II = Base and Overlay Districts (specific district chapters live here); Article III = regulations applying to some/all districts; Article IV = administration and permits. § 18.01.030.

District-by-district (what Title 18 actually names and says)

Note: each district header below uses the ordinance’s actual short name; the ordinance text for each district is cited by the controlling chapter/section where available. Where numeric standards are not present in the retrieved excerpts, I explicitly note that and point you to the chapter that should be consulted in the code or to Verify with the jurisdiction.

Residential — RS-3, RS-6 (Single‑family)

Purpose and typical uses

• The RS (single‑family) group is defined as RS-3 (Single‑Family, Low Density) and RS-6 (Single‑Family). These classifications are treated as “RS district” where used in the title.

Key dimensional/other standards

• Numeric setbacks, heights, lot coverage, and density for RS districts are located in the residential development tables in Article II (Chapter 18.04 and related sections). Specific numeric standards for standard RS lots were not present in the retrieved excerpts; consult Chapter 18.04 and the applicable MU/Small‑lot subsections for site‑specific variations. Verify with the jurisdiction.

Where it applies

• RS districts appear throughout single‑family neighborhoods shown on the Official Zoning Map (see § 18.01.080).

Multifamily — RM-20, RM-59

Purpose and typical uses

• RM districts are defined as RM-20 (Multifamily, Low Density) and RM-59 (Multifamily, Medium Density) and are grouped as “RM district” for many code provisions.

Key dimensional/other standards

• Density and form standards for multifamily are in Article II (Chapter 18.04 and related MU chapters); numeric entries for RM districts were not included in the retrieved snippets. See Chapter 18.04 and relevant development tables; verify parcel‑specific standards with the City.

Where it applies

• RM districts are used where the General Plan envisions multifamily development; exact locations are on the Official Zoning Map.

Mixed‑Use — MU-DC, MU-D, MU-SA, MU-SC, MU-NB, MU-SB, MU-N

Purpose and typical uses

• The MU family (Mixed‑Use) is intentionally defined with subtypes such as MU-DC (Downtown Core) and MU-N (Neighborhood Mixed‑Use). The ordinance sets pedestrian/transit orientation and a mix of residential + retail/office as core goals. See § 18.05.010.

Key dimensional standards (decision‑relevant)

• Density and floor‑area/density limits are explicitly tabled: for example, MU-DC-100 allows up to 100 units/net acre; minimum densities for many MU types are also specified in Table 18.05.030-1. See § 18.05.030 for MU tables.

Where it applies

• Downtown/core corridors, station areas, San Carlos Avenue and boulevard corridors as shown on the Zoning Map and referenced in MU chapter text.

Practical guidance

• Mixed‑use projects must meet both land‑use allowances in the MU chapter and the objective design standards and FAR/density tables in § 18.05.030. For façade, frontage, and objective design standards (many MU districts include these), consult the MU objective design rules in Chapter 18.05.

Commercial — NR (Neighborhood Retail), GCI, LC

Purpose and typical uses

• NR is the Neighborhood Retail district (small‑scale, neighborhood‑serving uses). GCI is General Commercial/Industrial; LC is Landmark Commercial. These are defined in the district list and in the corresponding district chapters.

Key standards and use limits

• Neighborhood hubs (rezoning to NR) are governed by the Neighborhood Hub (NH) Overlay District standards and require location and use limitations (Chapter 18.13). For example, NR uses are intended to be small‑scale neighborhood retail and service uses when established through the NH overlay process. § 18.13.030–040.

Where it applies

• Commercial districts are mapped downtown, along major corridors and at designated neighborhood hubs on the Official Zoning Map. Verify exact parcels with the City Zoning Map.

Industrial — IA, IL, IH, IP

Purpose and typical uses

• The ordinance identifies several industrial district types: IA (Industrial Arts), IL (Light Industrial), IH (Heavy Industrial), IP (Industrial Professional). These districts have specific use lists and performance conditions in Chapter 18.07.

Key dimensional/decision standards (from the ordinance tables)

• Table 18.07.030 contains lot size minima and height rules; examples from the retrieved excerpt:
  • Minimum lot size: IA 5,000 sq ft; IL 40,000 sq ft; IH 20,000 sq ft; IP 1 acre.
  • Maximum heights vary by subdistrict and may require permits (see Table 18.07.030 and § 18.07.030).

Where it applies

• Industrial districts are mapped in San Carlos' industrial zones (see Official Zoning Map). Confirm parcel classification with the City.

Public & Semi‑Public — P, PK, OS

Purpose and typical uses

• P (Public), PK (Park), OS (Open Space) provide for public facilities, parks, schools and similar uses. See Chapter 18.08 and § 18.08.010 for stated purposes.

Key dimensional standards

• Table 18.08.030 prescribes development standards for these districts; example values include maximum height 30 ft and front setback 30 ft for several P/PK/OS classifications — see § 18.08.030.

Where it applies

• Mapped public lands, parks, open space and school properties per the Official Zoning Map.

Airport — A

Purpose and typical uses

• The Airport District addresses San Carlos Airport–adjacent uses and references the San Mateo County Airport Use Plan. See Chapter 18.09.

Key dimensional standards

• Table 18.09.040 (Airport District) in the ordinance lists: maximum height 50 ft (subject to airport plan), minimum front/street side yards 15 ft, minimum site area 20,000 sq ft (see § 18.09.040).

Where it applies

• Properties adjacent to San Carlos Airport as mapped and described in Chapter 18.09.

Planned Development — PD

Purpose and typical uses

• PD permits site‑tailored standards for larger or integrated projects and is intended to allow flexibility (setbacks, FAR, parking, etc.) when consistent with the General Plan; see § 18.10.010.

Zoning Map designation and process

• A PD is shown on the Zoning Map as “PD” plus the plan number and requires City Council adoption. See § 18.10.020–040 and Chapter 18.36 for PD procedures.

Overlay Districts — G (Gateway), H (Hillside), SDM, NH (Neighborhood Hub), Northeast Area Overlay

Purpose and applicability

• Overlays add location/issue‑specific rules (design, hillside, streams, neighborhood hubs). The NH Overlay (Neighborhood Hub) and Northeast Area Overlay are examples with specific processes and conditional use rules; see Chapters 18.13 and 18.14A.

Key rules called out in the ordinance

• NH requires demonstration of neighborhood hub criteria and rezoning requirements for NR uses (§ 18.13.030–040).
• The Northeast Area Overlay currently requires conditional use permits for most projects until a specific plan is adopted and lists many permit exceptions; see § 18.14A.010–040.

Practical guidance

• Always check overlay maps in the Official Zoning Map (per § 18.01.080) because overlays can impose conditional use permit triggers or additional design/landscaping/parking obligations.

Decision‑relevant at‑a‑glance table

Checklist — what an applicant must confirm (minimum)

• Verify the parcel’s base zoning on the Official Zoning Map (the map is part of the code by reference) — § 18.01.080.
• Confirm whether any overlay district (NH, Hillside, Northeast Area, SDM, etc.) applies to the parcel — overlays can change permit triggers and conditions — see Chapter 18.13, 18.12, 18.14A.
• Check the base‑district land‑use table for permitted/conditional uses and any use‑specific notes (Article II; e.g., MU, NR, IA tables) — see § 18.05.010–030, § 18.07.030.
• Pull applicable development standards (height, setbacks, lot coverage, FAR/density) from the district table(s) that control the parcel — e.g., Table 18.05.030‑1 for MUs, Table 18.07.030 for industrial, Table 18.08.030 for public.
• Confirm whether design review or discretionary permits (use permit, conditional use, variance, PD rezoning) are required — see the Administration and permits chapters and the overlay rules; design review rules are in the design review chapter.
• Calculate parking requirements and loading rules and compare with what the district and overlay require (see parking rules).
• If proposing an ADU, consult the ADU chapter and applicable California ADU law; Title 18 has rules plus state law may control — see the ADU material.

Helpful internal links while you work: San Carlos Land Use; San Carlos Development Standards; San Carlos Parking; San Carlos Design Review; San Carlos Overlay Districts; San Carlos ADUs.

Risks & Ambiguities

Plain‑English summary

The San Carlos Zoning Ordinance (Title 18) maps every parcel to a base district (RS, RM, MU, NR, IA/IL/IH/IP, P/PK/OS, A, PD, etc.) and may layer overlay districts on top; each base and overlay chapter lists what uses are allowed and the development standards (height, setbacks, density, lot size, and special rules). The Official Zoning Map is the controlling map (the map is adopted by reference) and changes to boundaries or district text follow public hearing procedures with findings required for amendments. Key numeric standards are in district tables (for example § 18.05.030 for mixed‑use densities and § 18.07.030 for industrial lot/height rules).

Source References

• San Carlos Zoning Ordinance (Title 18) — Introductory provisions, purpose, structure: § 18.01.010 – § 18.01.030.
• Official Zoning Map and district boundary rules: § 18.01.080.
• Mixed‑Use districts purpose and development standards (tables): § 18.05.010; § 18.05.030.
• Public and Semi‑Public district standards and supplemental regs: § 18.08.010; § 18.08.030; § 18.08.040.
• Airport District standards: § 18.09.040.
• Industrial district development standards (lot sizes, heights): § 18.07.030.
• Planned Development rules and PD zoning map designation: § 18.10.010–040.
• Neighborhood Hub (NH) Overlay: Chapter 18.13 (purpose, applicability, rezoning to NR): § 18.13.010–040.
• Northeast Area Overlay District: Chapter 18.14A (purpose, applicability, conditional use permit triggers): § 18.14A.010–040.
• Small‑lot single‑unit development standards: Table 18.04.100‑G (project FAR 0.45, lot coverage 35%, front setback 10 ft etc.) § 18.04.100-G.
• Zoning amendments criteria and required findings: § 18.35.080.
• Variance authority and rules: Chapter 18.32.

Retrieved passages

• San Carlos Zoning Code (§ 1) High relevance show source text
• San Carlos Zoning Code (Section numbers) High relevance show source text
• San Carlos Zoning Code (Chapter 18.10) High relevance show source text
• San Carlos Zoning Code (§ 3) High relevance show source text
• San Carlos Zoning Code (§ 3) High relevance show source text
• San Carlos Zoning Code (§ 3) High relevance show source text
• San Carlos Zoning Code (§ 3) High relevance show source text
• San Carlos Zoning Code (Article I) High relevance show source text

Cited sections

• San Carlos Zoning Ordinance (Title 18) — Introductory provisions, purpose, structure: **§ 18.01.010 – § 18.01.030**. (Title 18)
• Official Zoning Map and district boundary rules: **§ 18.01.080**. (§ 18.01.080)
• Mixed‑Use districts purpose and development standards (tables): **§ 18.05.010; § 18.05.030**. fileciteturn0file14turn0file18 (§ 18.05.010)
• Public and Semi‑Public district standards and supplemental regs: **§ 18.08.010; § 18.08.030; § 18.08.040**. fileciteturn0file6turn0file0 (§ 18.08.010)
• Airport District standards: **§ 18.09.040**. (§ 18.09.040)
• Industrial district development standards (lot sizes, heights): **§ 18.07.030**. (§ 18.07.030)
• Planned Development rules and PD zoning map designation: **§ 18.10.010–040**. (§ 18.10.010)
• Neighborhood Hub (NH) Overlay: **Chapter 18.13** (purpose, applicability, rezoning to NR): **§ 18.13.010–040**. (Chapter 18.13)
• Northeast Area Overlay District: **Chapter 18.14A** (purpose, applicability, conditional use permit triggers): **§ 18.14A.010–040**. (Chapter 18.14A)
• Small‑lot single‑unit development standards: **Table 18.04.100‑G** (project FAR **0.45**, lot coverage **35%**, front setback **10 ft** etc.) **§ 18.04.100-G**. (§ 18.04.100-G)
• Zoning amendments criteria and required findings: **§ 18.35.080**. (§ 18.35.080)
• Variance authority and rules: Chapter **18.32**.
• SanCarlos_ZoningCode.md

• Official San Carlos code library