Millbrae — Overlay Districts

Last reviewed: July 2, 2026

Overview

This page explains how Millbrae’s zoning ordinance treats overlay/combining and special plan districts that modify or add rules on top of base zoning. The ordinance uses a formal combining district (the -O suffix), several plan-based districts such as the Millbrae Station Area Planned Development (MSAPD) and the Downtown and El Camino Real Specific Plan (DTECRSP), and citywide plan-consistency rules (for example airport compatibility). For where a property sits and which overlay applies, always start with the official zoning map and district text in the code; see the Millbrae zoning & planning overview for city‑level context and next steps. (/us/california/millbrae)

How Millbrae defines overlays and special/combing districts

• The code establishes a formal combining district mechanism (suffix -O) to add office uses to an otherwise residential zone: § 10.05.0310 .
• A site-specific planned/development district process (the PD and MSAPD) and Specific Plan districts (for example DTECRSP) function like overlays because they impose area-specific uses, design rules and standards in addition to the base zoning; see § 10.05.1510 – § 10.05.1575 for PD rules and § 10.05.1700 – § 10.05.1715 for MSAPD (Millbrae Station Area) standards and process.
• All district boundaries are shown on the official zoning map and are incorporated into the chapter; boundary determination rules apply where the map is ambiguous: § 10.05.0320 and § 10.05.0330.

Below are the Millbrae overlay/special districts and the code sections that control them. Each subsection gives the ordinance purpose, typical allowed uses, key dimensional/development standards (or where they are set), and where the overlay applies.

Combining district ("-O"): Office Combining (the main overlay mechanism)

Purpose

• The code creates a combining district designated by the suffix -O to allow office uses to be combined with underlying districts: § 10.05.0310 . Article IX describes the Office Combining or "-O" district in detail: § 10.05.0900 – § 10.05.0930.

Typical permitted / conditional uses

• The -O district provides no permitted uses by right; it allows office uses only by conditional use permit—specifically general offices, medical offices, and professional offices as conditional uses: § 10.05.0910 .

Key dimensional / development standards

• Development standards (building height, site standards, lot width, lot coverage, front/side/rear yards) in an -O area are explicitly the same as those for the residential district to which the combining district is attached: § 10.05.0930 .
• Parking requirements for any uses introduced by the combining district reference the city’s parking table (MMC § 10.05.2100) — see the district text and the city parking table for exact vehicle-count requirements: § 10.05.0930 . Link to Millbrae parking information when checking numbers. (/us/california/millbrae/parking)

Where and how it is applied

• The -O designation is limited by the ordinance to lots that are (A) zoned residential, (B) abut commercial zoning, and (C) are on a block where the change from residential to nonresidential occurs within the block face; adding the -O is initiated via application to the city council with supporting proof: § 10.05.0900 and § 10.05.0920.

Practical guidance

• If a property owner wants office use on a qualifying residential parcel, expect a city‑council initiation (for the combining district) and then a conditional use permit reviewed by the planning commission; site changes that involve new structures or exterior alterations require design review: § 10.05.0920 and § 10.05.0930. Link to the design review guidance for process details. (/us/california/millbrae/design-review)

Planned Development / Specific Plan style overlays

Planned Development (PD) district

Purpose

• The PD procedure authorizes project‑specific zoning tied to a city‑approved conceptual development plan; uses must be consistent with the General Plan and the approved conceptual plan: § 10.05.1510 and § 10.05.1520.

Typical permitted uses

• The code allows “Any use consistent with the Millbrae General Plan” that is included in an approved conceptual development plan; exact uses are set by the approved plan and ordinance that creates the PD: § 10.05.1510 and § 10.05.1520. See Millbrae Land Use for General Plan context. (/us/california/millbrae/land-use)

Key dimensional / development standards

• The conceptual development plan must show proposed development standards (heights, setbacks, densities/FAR, parking, open space) and the city may adopt project‑specific standards by ordinance; precise development plans and design review follow approval: § 10.05.1520, § 10.05.1540. Link to the development standards guide when assembling your materials. (/us/california/millbrae/development-standards)

Where and how it is applied

• The PD overlay is applied by zone change ordinance after city council action on the conceptual plan; no building permits consistent with the PD can issue until a precise development plan is effective: § 10.05.1525 and § 10.05.1570.

Practical guidance

• PDs are effectively bespoke overlays: read the adopted PD ordinance and the approved conceptual and precise plans closely because the PD will supersede or modify base standards. For design and sign programs the PD often contains specific provisions; when in doubt, check the PD ordinance and the precise development plan conditions. § 10.05.1545 lists the minimum content of precise plans.

Millbrae Station Area Planned Development (MSAPD) — MSASP

Purpose

• The MSAPD implements the Millbrae Station Area Specific Plan (MSASP) and prescribes area-wide planning and design principles and standards for the station area: § 10.05.1700 and § 10.05.1705.

Typical permitted uses

• Site‑specific uses in the MSAPD are governed by the MSASP; the ordinance allows uses consistent with the MSASP and subjects many applications to conditional use and design review: § 10.05.1710.

Key dimensional / development standards

• The MSASP is incorporated by reference into the zoning ordinance; the area-specific development standards and design guidelines are located in the MSASP rather than spelled out in full in the zoning chapter: § 10.05.1705.

Where and how it is applied

• The MSAPD covers the Millbrae Station area (see the city’s official zoning map) and requires site development plans and environmental review per the MSASP and code procedures: § 10.05.1715 – § 10.05.1720.

Practical guidance

• Because the MSASP is incorporated by reference, applicants must read the MSASP for area standards (heights, open space, circulation) and follow the code’s site development plan and design review procedures; the planning commission looks for MSASP conformance when acting on proposals. § 10.05.1720.

Other special/plan overlay references

• Downtown and El Camino Real Specific Plan (DTECRSP) appears as a named district (Article XI) in the zoning table of contents: § 10.05.1100 (Article XI). The code identifies DTECRSP as a distinct district in the zoning list § 10.05.0300 but the detailed DTECRSP text was not included in the retrieved materials here. Not found in retrieved materials for specific DTECRSP standards.

• Airport land‑use compatibility is treated as a citywide consistency overlay via Article XVI references; several district sections require compliance with the Airport Land Use Compatibility Plan and related evaluations (e.g., noise, avigation easement, and airspace protection): see § 10.05.1020.D (C district) and multiple other districts that reference Article XVI. Confirm airport-specific constraints in Article XVI and with the San Francisco Airport ALUCP.

Quick decision‑relevant table

Checklist

• Confirm the property’s base zoning and any overlays on the official zoning map (§ 10.05.0320).
• If seeking office uses in a residential zone, verify eligibility for -O combining status (abuts commercial; blockface condition) and prepare the city‑council initiation documentation (§ 10.05.0900, § 10.05.0920).
• Assemble a conceptual development plan if pursuing a PD or a site development plan/precise plan if in MSAPD; include development standards, architectural sketches, landscape plan, and traffic/utility information as required (§ 10.05.1520, § 10.05.1545, § 10.05.1715).
• Evaluate parking requirements in MMC § 10.05.2100 and the city’s parking guidance when calculating required spaces (the overlay will point to the parking table) (/us/california/millbrae/parking).
• For any new structures or exterior changes, prepare for design review and the planning commission process (see district references to design review and the city’s design review page) (/us/california/millbrae/design-review).
• Check for airport constraints and ALUCP requirements; see Article XVI references in district sections (verify with airport ALUCP and city planning).
• If proposing accessory dwelling units, confirm overlay impact on ADU rules and applicable lot/development standards (see ADU guidance) (/us/california/millbrae/adu).

Risks & Ambiguities

Plain‑English summary

Millbrae does overlays mainly two ways: (1) a formal combining district identified by the -O suffix that allows office uses on qualifying residential lots (by conditional permit) and (2) area‑specific plan/PD districts (like the MSAPD and DTECRSP) that set project‑specific rules; the code tells you where those overlays are on the official zoning map and points to the specific plan or the PD ordinance for the numeric standards and processes—always check the cited sections and the adopted plan documents before designing. § 10.05.0310, § 10.05.0900–0930, § 10.05.1510–1540, § 10.05.1700–1715.

Source References

• Millbrae Municipal Code, Title 10 (Planning & Zoning), Chapter 10.05 Zoning (downloaded from the city code where indicated). Relevant sections cited above: § 10.05.0310, § 10.05.0320, § 10.05.0330, § 10.05.0400, § 10.05.0900–0930, § 10.05.1000–1030, § 10.05.1510–1545, § 10.05.1700–1725, § 10.05.2100 (parking references). Source file: https://ecode360.com/MI4538

• Note: Several district sections reference Article XVI (Airport Land Use Compatibility Plan Consistency) and the MSASP (incorporated by reference). Where the retrieved materials reference or incorporate external documents (MSASP, Article XVI text), the full text of those external documents was not reproduced in the provided files. Verify those external plans with the city.

Retrieved passages

• Millbrae Zoning Code (Article XVI) High relevance show source text
• Millbrae Zoning Code (§ 10.05.1510.) High relevance show source text
• Millbrae Zoning Code (§ 10.05.1540) High relevance show source text
• Millbrae Zoning Code (§ 10.05.0320.) Medium relevance show source text
• Millbrae Zoning Code (chapter in) Medium relevance show source text
• Millbrae Zoning Code (§ 10-1.7) Medium relevance show source text
• Millbrae Zoning Code (§ 14) Medium relevance show source text
• Millbrae Zoning Code (Chapter 12.75) Medium relevance show source text
• Millbrae Zoning Code (section shall) Medium relevance show source text
• Millbrae Zoning Code (§ 6) Medium relevance show source text
• Millbrae Zoning Code (§ 10.05.0330.) Medium relevance show source text

Cited sections

• Millbrae Municipal Code, Title 10 (Planning & Zoning), Chapter 10.05 Zoning (downloaded from the city code where indicated). Relevant sections cited above: **§ 10.05.0310**, **§ 10.05.0320**, **§ 10.05.0330**, **§ 10.05.0400**, **§ 10.05.0900–0930**, **§ 10.05.1000–1030**, **§ 10.05.1510–1545**, **§ 10.05.1700–1725**, **§ 10.05.2100** (parking references). Source file: (Title 10)
• Note: Several district sections reference Article XVI (Airport Land Use Compatibility Plan Consistency) and the MSASP (incorporated by reference). Where the retrieved materials reference or incorporate external documents (MSASP, Article XVI text), the full text of those external documents was not reproduced in the provided files. Verify those external plans with the city. (Article XVI)
• Millbrae_ZoningCode.md

• Official Millbrae code library