San Carlos — Overlay Districts

Last reviewed: July 2, 2026

Overview

San Carlos uses a set of overlay districts that sit on top of the city's base zoning to add location‑specific rules (design, setbacks, special permit triggers, and landscape requirements) without replacing the underlying base zone. Key local overlays are the Gateway (G), Hillside (H), Stream Development and Maintenance (SDM), Neighborhood Hub (NH), and the Northeast Area Overlay; each chapter spells out purpose, where it applies, and the controlling standards and permit requirements. For project-level work you will need to read both the overlay chapter and the underlying base zone development standards in the city's development standards and parking chapters to determine the full rule set (see San Carlos Development Standards and San Carlos Parking for those cross-references).

How to read this page

This page stays strictly to what the San Carlos Zoning Ordinance (Title 18) says about overlay districts. All requirements below are grounded in the ordinance; code citations appear as the controlling § number and the originating ordinance file reference. For procedure and design submittal rules, also consult the San Carlos Design Review and San Carlos Development Standards pages.

Chapter-by-chapter, district-by-district breakdown

Gateway Overlay — G

• Purpose: The Gateway (G) Overlay is intended to create clear, attractive points of arrival to the city and emphasize gateway corners and plazas (§ 18.11.010) .
• Where it applies: To the areas identified as gateways on the Zoning Map (§ 18.11.020) .
• Typical controls / standards:
  • Corner emphasis: buildings are required near corners within specified distances and vertical elements are encouraged at corners to create a sense of entry (§ 18.11.030(A)) .
  • Public plaza / landscaped areas: minimum horizontal dimension 20 ft in primary gateway corners; landscaped setback 15 ft in certain gateways such as Brittan Avenue at Highway 101 (§ 18.11.030) .
  • Design criteria & reduction: design review can reduce or waive some gateway requirements if the review authority finds the design criteria are met (§ 18.11.040; 18.11.030(C)) .
• How it interacts with other rules: Gateway requirements apply in addition to the underlying base district; where conflicts arise the most restrictive controls apply (see general conflict rule in the SDM chapter) — verify with the Planning Division for parcel-specific interactions (§ 18.11.020; related conflict language appears in other overlays) .

Hillside Overlay — H

• Purpose: The Hillside (H) Overlay addresses development on steep slopes and hillside lots to protect visual, geologic, and drainage conditions and to reduce fire risk, including materials and color guidance (§ 18.12 — chapter heading and standards) .
• Where it applies: To mapped hillside areas shown on the Zoning Map (§ 18.12.*) .
• Key dimensional & design standards:
  • Materials and colors: earth‑tone palettes and fire-retardant exterior materials in high fire hazard areas are required (§ 18.12.*; colors/materials guidance) .
  • Landscaping: slope stabilization and screening requirements for retaining walls over 4 ft; fire hazard-compatible landscaping rules (§ 18.12.070) .
• Typical permitted uses: The overlay modifies development standards rather than the use list — permitted uses remain those of the underlying base district unless a specific overlay subsection restricts a use (Not found in retrieved materials for H limiting specific uses) .

Stream Development and Maintenance Overlay — SDM

• Purpose: The Stream Development and Maintenance (SDM) Overlay protects waterways and riparian functions and reduces flood and bank-failure hazards (§ 18.14.010) .
• Where it applies: To lots where any portion is within 25 feet of the top of bank of mapped creeks (Cordilleras, Belmont, Brittan, Pulgas) (§ 18.14.020) .
• Critical regulatory points:
  • Minimum setback: new development must be set back a minimum 25 ft from the top of bank (or another distance as specified by the Planning and Transportation Commission) (§ 18.14.030(A)) .
  • What counts as development: includes structures, pools, driveways, parking areas, patios, decks, earth fill and broken concrete rubble, etc.; fences are allowed per § 18.15.040 and retaining walls or channel lining require federal/state permits and a building permit (§ 18.14.030(A)(1)) .
  • Top of bank determination: technical determination by applicant’s engineer subject to City Engineer review (§ 18.14.030(A)(2)) .
• Interaction with base district: SDM may be combined with any base district; where it conflicts with the base district the most restrictive provision controls (§ 18.14.020) .

Neighborhood Hub Overlay — NH

• Purpose: The Neighborhood Hub (NH) Overlay implements the General Plan concept for small, neighborhood-serving retail and services that fit within residential areas (§ 18.13.010) .
• Where it applies: To residential areas west of El Camino Real and at least 1/2 mile from MU-DC and MU-D district boundaries (§ 18.13.020) .
• Establishing a hub and uses:
  • Neighborhood hubs are created by General Plan amendment and rezoning to the NR (Neighborhood Retail) district; hubs must be at least 1/2 mile from existing neighborhood-serving retail or other NR boundaries (§ 18.13.030(A), 18.13.030(B)) .
  • Rezoning to NR within NH is subject to additional requirements and when rezoned land uses are limited to neighborhood‑serving retail and service uses (§ 18.13.040(A)) .
• Practical effect: NH does not automatically change uses on a lot; a formal General Plan amendment + rezoning is required to create NR uses within NH (§ 18.13.030–040) .

Northeast Area Overlay — (18.14A) Northeast Area Overlay District

• Purpose and scope: The Northeast Area Overlay District is intended to hold development in the Northeast Area to the design and compatibility standards of the Northeast Area Specific Plan until that Specific Plan is adopted (§ 18.14A.010–.020) .
• Permit triggers and interim controls:
  • Until the Specific Plan is adopted, a broad range of activity in the Northeast Area requires a conditional use permit — including lot line adjustments, subdivisions, design review, use permits, planned development, zoning amendments, waivers, variances and other discretionary approvals (§ 18.14A.030(A)) .
  • There are discrete exemptions (for example, pre-existing complete applications prior to April 25, 2022; sign permits; applications for solar PV; interior work; ordinary maintenance; protected tree removal with permit) (§ 18.14A.030(B)) .
  • Approvals require the findings set out in § 18.30.060 for use permits (findings) and must meet environmental review obligations (§ 18.14A.040; ties to Chapter 18.30 & 18.27 procedures) .
• Practical impact: Projects in the Northeast Area face a higher discretionary bar and likely need Planning and Transportation Commission review; verify whether the Specific Plan has been adopted and whether the moratorium/conditional-use requirement remains in force (see § 18.14A) .

Quick reference table — most decision-relevant overlay standards

Practical guidance & plain-English interpretation (what applicants actually need to do)

• First, confirm whether the parcel is mapped inside any overlay on the official Zoning Map; overlays are map‑based (e.g., G, H, SDM, NH, 18.14A) (§ 18.11.020; § 18.14.020; § 18.13.020) .
• Read the overlay chapter word‑for‑word and then read the underlying base district chapter (RS‑, RM‑, MU‑, NR, etc.) because overlays generally modify development standards rather than replace the use table (§ 18.01.030; § 18.01.070) . For numerical development standards consult the San Carlos Development Standards pages and confirm off‑street vehicle and bicycle parking requirements on the San Carlos Parking page.
• Where an overlay imposes a discretionary trigger (for example, the Northeast Area Overlay requires a conditional use permit for most work), expect public hearing review by the Planning and Transportation Commission and the findings listed for use permits (§ 18.14A.030; § 18.30.060) .
• If your project is in the SDM area near a creek, you must show a top‑of‑bank determination by an engineer and maintain a minimum 25‑ft setback for new development unless the Commission sets a different distance (§ 18.14.030) .
• For Gateway corners expect requirements for plazas, corner building placement, or landscaped setbacks; if a strict requirement would impede your design, the design review process can be used to request reductions but must meet the § 18.11.040 criteria (§ 18.11.030–.040) .
• Overlays can require or modify landscaping and screening; see the overlay chapter(s) and the general landscaping chapter for required planting, screening of retaining walls, and fire‑hazard landscaping rules (§ 18.12.070; Chapter 18.18) .

Note: overlay chapters do not (in the retrieved materials) comprehensively address ADUs; the local ADU rules and state ADU law govern. Consult the San Carlos ADUs and California ADU law pages for ADU‑specific rules (Not found in retrieved materials for overlay‑specific ADU exceptions) .

Checklist (what an applicant must satisfy before filing)

• Confirm parcel overlays on official Zoning Map and note overlay map extents (Verify with Planning) (§ 18.11.020; § 18.14.020; § 18.13.020)
• Read the overlay chapter(s) that apply and extract any numeric standards (setbacks, minimum plaza dimensions, landscape widths) (§ 18.11.030; § 18.14.030; § 18.12.070)
• Read the underlying base district standards and calculate combined setbacks, coverage, height limits (see San Carlos Development Standards) (§ 18.01.030; Table listings)
• Determine whether discretionary approval is required (e.g., conditional use permit in Northeast Area) and prepare required findings and environmental review materials (§ 18.14A.030; § 18.30.060)
• For SDM parcels: commission-approved top‑of‑bank determination and show 25‑ft minimum setback or alternative approved by Commission (§ 18.14.030(A))
• Prepare landscaping plan consistent with overlay and Chapter 18.18 rules; include slope stabilization where required (§ 18.12.070; Chapter 18.18)
• If seeking a reduction (e.g., in Gateway), prepare design-review package addressing the criteria in § 18.11.040 and consult the San Carlos Design Review page (§ 18.11.040)

Risks & Ambiguities

Plain-English Summary

San Carlos overlay districts (the G, H, SDM, NH, and Northeast Area overlays) add place‑specific design, setback, landscaping and discretionary‑permit rules on top of the base zone. Typical effects are special corner/plaza rules in the Gateway (G) overlay (§ 18.11.030) , a 25‑ft creek setback in the SDM overlay (§ 18.14.030) , and added permit triggers (notably a broad conditional‑use requirement) in the Northeast Area until a Specific Plan is adopted (§ 18.14A.030) . Verify overlay mapping, follow both the overlay chapter and the underlying base district rules, and expect discretionary hearings where the overlay requires them.

Source References

• § 18.11.010–18.11.040, Gateway (G) Overlay District — ordinance chapter text and development standards
• § 18.12.* (Hillside Overlay) — hillside materials, landscaping and slope rules (see § 18.12.070 for landscaping)
• § 18.13.010–18.13.040, Neighborhood Hub (NH) Overlay District — purpose, applicability, hub establishment and rezoning to NR
• § 18.14.010–18.14.030, Stream Development and Maintenance (SDM) Overlay District — purpose, applicability, 25 ft stream setback and definitions
• § 18.14A.010–18.14A.040, Northeast Area Overlay District — map boundary, conditional‑use permit requirements, findings
• § 18.01.030, § 18.01.070 — structure of zoning regulations, list of base and overlay districts (table)
• § 18.30.060–.070 — use permit findings and conditions of approval referenced by overlays that require discretionary permits

Retrieved passages

• San Carlos Zoning Code (chapter shall) High relevance show source text
• San Carlos Zoning Code (Chapter 18.11) High relevance show source text
• San Carlos Zoning Code (Section 18.14A.020) High relevance show source text
• San Carlos Zoning Code (Chapter 18.14) High relevance show source text
• San Carlos Zoning Code (§ 3) Medium relevance show source text
• San Carlos Zoning Code (§ 4) Medium relevance show source text
• San Carlos Zoning Code (§ 4) Medium relevance show source text
• San Carlos Zoning Code (Section numbers) Medium relevance show source text

Cited sections

• § 18.11.010–18.11.040, Gateway (G) Overlay District — ordinance chapter text and development standards (§ 18.11.010)
• § 18.12.* (Hillside Overlay) — hillside materials, landscaping and slope rules (see § 18.12.070 for landscaping) (§ 18.12.)
• § 18.13.010–18.13.040, Neighborhood Hub (NH) Overlay District — purpose, applicability, hub establishment and rezoning to NR (§ 18.13.010)
• § 18.14.010–18.14.030, Stream Development and Maintenance (SDM) Overlay District — purpose, applicability, **25 ft** stream setback and definitions (§ 18.14.010)
• § 18.14A.010–18.14A.040, Northeast Area Overlay District — map boundary, conditional‑use permit requirements, findings (§ 18.14A.010)
• § 18.01.030, § 18.01.070 — structure of zoning regulations, list of base and overlay districts (table) (§ 18.01.030)
• § 18.30.060–.070 — use permit findings and conditions of approval referenced by overlays that require discretionary permits (§ 18.30.060)
• SanCarlos_ZoningCode.md

• Official San Carlos code library