San Carlos — Development Standards

Last reviewed: July 2, 2026

Overview

This page summarizes the City of San Carlos zoning development standards (setbacks, heights, lot coverage, density, FAR) as written in the municipal zoning ordinance (Title 18). It is focused on what the Code actually requires in each zoning district and how the City measures those limits; interpretive guidance and application-level advice are provided, but parcel‑specific determinations require verification with the City. See the city's baseline zoning reference at San Carlos Zoning for map and district definitions.

Notes up front:

• Measurements (how FAR, lot coverage, height, setbacks are calculated) are controlled by the Code’s Rules of Measurement; see § 18.03.050, § 18.03.090, and § 18.03.100 for methodology (and related exceptions) .
• Modifications and minor deviations are possible through administrative waivers under § 18.33.020 (up to 10% on many dimensional standards; some items are excluded) .
• Projects that change objective standards (massing, facades, garage placement, landscaping, etc.) are often subject to City Design Review; see Chapter 18.29 referenced in the Code .

The City also ties landscaping, screening and other site‑level requirements to development standards; see San Carlos Landscaping and Screening for the municipal chapter referenced inside many district tables.

How the Code organizes standards (quick orientation)

The Code groups development standards by district chapters/tables (examples below). When I list a numeric standard I cite the controlling Code table/section and the file extract used:

• Residential single‑family: § 18.04.030 (Tables for RS-3 and RS-6) .
• Residential multi‑family (RM): § 18.04.050 (RM‑20, RM‑59, RM‑100) .
• Small‑lot single‑unit subdivisions: Table 18.04.100‑G under § 18.04.100 (explicit small‑lot numeric limits) .
• Mixed‑use (MU) districts: § 18.05.030 (density and commercial FAR tables; many MU subtypes such as MU‑DC‑100, MU‑D‑100, MU‑N‑120, etc.) .
• Commercial districts (NR, GCI, LC): § 18.06.030 (setbacks, heights, FAR) .
• Industrial districts (IA, IL, IH, IP): § 18.07.030 (lot sizes, heights, FAR caps) .
• Public / semi‑public districts (P, PK, OS): § 18.08.030 (standard yards, heights) .
• Airport district (A) uses and standards: § 18.09.030 (uses) and § 18.09.040 (development standards, height limits tied to Airport plan) .
• Planned Development (PD) districts: project‑level standards are established by the approved PD plan; Chapter § 18.10.040 lists required elements that a PD must set (setbacks, FAR, heights, etc.) .

I link to specific City pages when referring to related topics (for applicant steps and non‑zoning rules): San Carlos Parking, San Carlos Overlay Districts, San Carlos ADUs, and the state code California Building Standards Code.

District-by-district breakdown (purpose, permitted use flavor, and the most relevant dimensional standards)

Note: every district name below is bolded; the numeric standards are pulled from the Code tables cited after each district.

Residential Single‑Family — RS-3 and RS-6

Purpose / typical uses: single‑family detached neighborhoods; RS‑3 (lower density) and RS‑6 (smaller lots) are the City’s single‑family zones. See the residential standards table in § 18.04.030 .

Key standards (selected):

• Maximum density: RS‑3 = 3 units/acre, RS‑6 = 6 units/acre (Table in § 18.04.030) .
• Maximum height: 28 ft (both districts) — see § 18.04.030 and related height exceptions in § 18.15.060 .
• Setbacks: front, interior side, street side and rear standards are prescribed in § 18.04.030 (see the table for story‑by‑story details) .
• Lot coverage / MFA: RS‑6 has a Maximum Floor Area formula for certain lot sizes; consult § 18.04.030 and the Rules of Measurement § 18.03 when calculating lot coverage/MFA .

Practical note: lots created by new subdivision follow Table 17.16.030 referenced in the RS table; if your project is a small‑lot subdivision, see the Small Lot table under § 18.04.100 below for different setbacks and a site‑wide FAR cap .

Residential Multi‑Family — RM‑20, RM‑59, RM‑100

Purpose / typical uses: increasing density multifamily. See § 18.04.050 for complete lot/density/height/setback tables .

Key standards (selected):

• Density: RM‑20 = 20 u/ac, RM‑59 = 59 u/ac, RM‑100 = 100 u/ac (Table in § 18.04.050) .
• Max height: RM‑20 = 35 ft, RM‑59 = 50 ft, RM‑100 = 60 ft (with transitional limits adjacent to RS districts) — see § 18.04.050 and § 18.15.060 for height exceptions .
• Setbacks: typical front = 15 ft, interior side = 5 ft (RM‑20) with variations for larger RM zones — full table: § 18.04.050 .
• Lot coverage / FAR: Lot coverage caps are districted (65% for RM‑20, 75% for RM‑59/100); the ordinance indicates “No maximum FAR for residential buildings” for many RM residential uses — see § 18.04.050 and Rules of Measurement § 18.03 for what counts toward FAR .

Important transitional rule: when RM‑59/RM‑100 back onto an RS district, the Code prescribes transitional setbacks, lower heights, and planted buffers; see the RM table notes in § 18.04.050 .

Small‑Lot Single‑Unit / Small‑Lot Subdivision (Table 18.04.100‑G)

Purpose / where it applies: special standards for small‑lot single‑unit subdivisions; see Table 18.04.100‑G in § 18.04.100 .

Key standards (selected):

• Maximum Project Site FAR: 0.45 (site‑wide) — Table 18.04.100‑G under § 18.04.100 .
• Maximum Lot Coverage: 35% (project site) — § 18.04.100 (Table 18.04.100‑G) .
• Maximum height: 28 ft (subject to Hillside Overlay — see Chapter 18.12) — § 18.04.100 .
• Setbacks (per individual lot within the small‑lot project): front = 10 ft (5 ft for porch) ; side = 4 ft (1–2 story) / 8 ft (3‑story) ; rear = 15 ft (4 ft for detached garage on alley) — Table 18.04.100‑G (§ 18.04.100) .

Practical note: the small‑lot rules explicitly require building orientation and minimum landscaping/open space amounts; see § 18.04.100 for the full list .

Mixed‑Use Districts — MU‑ series (e.g., MU‑DC‑100, MU‑N‑120, etc.)

Purpose / typical uses: higher intensity, mixed residential + commercial; specific MU subtypes (downtown core, neighborhood, etc.) have separate density and FAR caps. See § 18.05.030 for the set of MU tables and subdistricts .

Key standards (selected):

• Maximum density examples: some MU districts allow up to 120 units/net acre in higher MU subtypes; consult § 18.05.030 for the specific MU subtype caps (e.g., MU‑D‑120, MU‑SC‑120) .
• Commercial FAR (commercial‑only): ranges by MU subtype (example: MU‑DC‑100 = 2.5, MU‑D‑100 = 3.0, many others 3.0) — see § 18.05.030 table for the complete list and the separate rules when a mixed building contains both uses .
• Residential FAR: many mixed‑use tables state “residential only development — n/a (no maximum FAR)” — see § 18.05.030; Rules of Measurement (§ 18.03.090) define what is excluded from FAR calculation (below‑grade areas, certain parking, small garages, etc.) .

Design and build‑to rules in MU districts include massing break, ground‑floor commercial height, and corner build‑to areas; see the MU tables in § 18.05.030 and the illustrations/notes for specifics .

Commercial Districts — NR, GCI, LC

Purpose / typical uses: neighborhood retail (NR), general commercial/industrial (GCI), limited commercial (LC) — see § 18.06.030 .

Key standards (selected):

• Maximum heights: NR = 35 ft (reduced to 28 ft within 50 ft of an RS district), GCI/LC = 50 ft (see § 18.06.030) .
• Setbacks: NR front = 0 ft build‑to with corner build‑to area rules; GCI/LC front = 10 ft (with minimum 30 ft from an RS boundary in some cases) — see table in § 18.06.030 .
• Maximum FAR: NR = 1.0, GCI = 2.0, LC = 2.0 (see § 18.06.030) .

Industrial Districts — IA, IL, IH, IP

Purpose / typical uses: industrial, warehousing, research. See § 18.07.030 for lot size minima, height limits, and FAR caps .

Key standards (selected):

• Minimum lot sizes vary (e.g., IA = 5,000 sq ft, IL = 40,000 sq ft, IP = 1 acre) and are explicit in § 18.07.030 .
• Max height / FAR: IA max height 28 ft (35 ft with use permit); IL 75 ft, IP 100 ft (with transitional limits near RS zones). FAR caps vary by district (e.g., IA 1.0, IL 0.5, IH 2.0, IP 2.0) — see § 18.07.030 .

Public / Semi‑Public — P, PK, OS

Typical rules: uniform 30 ft height limit and larger front/rear yards (front = 30 ft, interior side = 10 ft, rear = 20 ft) as set out in § 18.08.030 .

Airport District — A

Uses / standards are specific: permitted airport‑supporting uses listed in § 18.09.030; development standards in § 18.09.040 limit heights to 50 ft maximum and refer to the San Mateo County Airport Use Plan for operational limits; setbacks include minimum front and street‑side yards, and lot coverage caps (60%) .

Planned Development — PD

A PD rezoning requires an approved PD plan that establishes site‑specific development standards (minimum lots, setbacks, heights, FAR, parking, landscaping, architecture, etc.). The PD chapter lists the items that must be addressed in every PD plan (§ 18.10.040) .

Quick Decision‑Relevant Standards Table (examples)

(These are representative picks to orient applicants. Always consult the full district table cited above for the precise numeric rules that apply to a parcel.)

Rules of measurement and exclusions (what counts)

• FAR and lot coverage measurements follow the Rules of Measurement chapter. Examples of commonly excluded items from FAR and lot coverage: below‑grade floor area, certain parking areas, detached garages under specified size, unenclosed decks under certain heights — see § 18.03.090 and § 18.03.100 for the Code’s enumerated exclusions and figures used to calculate FAR/lot coverage .
• Setback determination rules (where the required yard is measured from, handling alley abutting lots, and planned street expansions) are in § 18.03.120 .
• Height measurement methodology and exceptions are in § 18.03.050 and § 18.15.060 (height exceptions) — consult both when your property has sloping grade, special roof forms, or is within an overlay district .

Design review, waivers, and exceptions

• Deviations from objective design standards (e.g., facade articulation, garage placement, roof form, driveway location, landscaping) are often subject to Design Review; Chapter 18.29 is identified in the Code as the procedural chapter for design review (see the list of standards that, if deviated from, trigger design review) .
• Administrative waivers (Director authority) can grant relief up to 10% for many dimensional standards (setbacks, lot coverage, height) under § 18.33.020. Waivers cannot be used for lot area/width/depth, max number of stories, minimum parking dimensions, residential density, or maximum FAR — see § 18.33.020 for the complete list of exclusions .

If the project proposes something beyond what an administrative waiver allows (or is in conflict with objective Code limits), expect a variance or a PD process; see San Carlos Variances and Exceptions.

Checklist (what an applicant must satisfy / provide)

• Confirm zoning district on the City’s zoning map and the exact district label (e.g., RS‑6, RM‑59, MU‑D‑120) — verify in the zoning map and then pull the corresponding table in § 18.04.030, § 18.04.050, § 18.05.030, etc. .
• Prepare dimensioned site plans that calculate lot coverage and FAR using the Rules of Measurement (§ 18.03.090, § 18.03.100) and identify any items that the Code excludes from FAR/coverage .
• Confirm applicable setbacks and height limits from the district table and flagged cross‑references (e.g., Hillside Overlay § 18.12, Height exceptions § 18.15.060) .
• Check whether the proposal triggers Design Review (Chapter 18.29) or any Overlay District standards (see San Carlos Overlay Districts) .
• If proposing an ADU, follow accessory dwelling standards in § 18.23.210 and note how State ADU allowances interact with local lot coverage/FAR calculations; see San Carlos ADUs and the state ADU rules California ADU law .
• Prepare landscaping plans consistent with district minimums and Chapter 18.18 references (landscaping percent requirements are noted in district tables) and consult San Carlos Landscaping and Screening .
• Evaluate whether a Director waiver under § 18.33.020 is appropriate for small deviations; if so, prepare the waiver justification and plans .
• Verify parking requirements and any driveway/garage setbacks per the municipal code and the City’s parking chapter (San Carlos Parking); parking counts and dimensional standards often affect site layout though the parking chapter text itself was not reproduced here.

Risks & Ambiguities

Plain‑English summary

San Carlos’ zoning tables set district‑specific caps on height, setbacks, lot coverage, and density (for example, RS‑6 = 28 ft height; RM‑59 = 50 ft; small‑lot projects often have a 0.45 FAR site cap) and define exactly how the city measures FAR and coverage; the controlling district tables are in Chapter 18 (see the cited sections) and measurement rules live in § 18.03 — verify details on a parcel by parcel basis with Planning.

Source References

• San Carlos Municipal Code — Rules of Measurement: § 18.03.050, § 18.03.090, § 18.03.100, § 18.03.120 (figures and text on measuring height, FAR, lot coverage, and setbacks) .
• § 18.04.030 — Development Standards, Residential Single‑Family districts (RS‑3, RS‑6) (tables and notes) .
• § 18.04.050 — Development Standards, Residential Multi‑Family districts (RM‑20, RM‑59, RM‑100) (tables and transitional rules) .
• § 18.04.100 (Table 18.04.100‑G) — Development Standards, Small Lot Subdivision / Single‑Unit development (site FAR = 0.45, 35% lot coverage, setbacks, open space requirements) .
• § 18.05.030 — Mixed‑Use district development standards (density & commercial FAR tables) .
• § 18.06.030 — Commercial district development standards (NR, GCI, LC) .
• § 18.07.030 — Industrial district development standards (IA, IL, IH, IP) .
• § 18.08.030 — Public and Semi‑Public district standards (P, PK, OS) .
• § 18.09.030 and § 18.09.040 — Airport district land uses and development standards (height limits tied to the Airport Use Plan) .
• § 18.10.040 — Planned Development requirements (items a PD plan must address) .
• § 18.23.210 — Accessory dwelling unit development standards and state exemption cross‑references (ADUs) .
• § 18.33.020 — Administrative relief / waiver authority (dimensional waivers up to 10%) .
• Design review triggers and list of objective standards that require review: Chapter 18.29 referenced in the Code (see Design Review extracts) .
• Related City pages used for internal linking and applicant resources: San Carlos Zoning, San Carlos Parking, San Carlos Overlay Districts, San Carlos ADUs, San Carlos Landscaping and Screening, San Carlos Design Review, California Building Standards Code.

Retrieved passages

• San Carlos Zoning Code (§ 3) High relevance show source text
• San Carlos Zoning Code (Section numbers) High relevance show source text
• San Carlos Zoning Code (Chapter 18.16) High relevance show source text
• San Carlos Zoning Code (§ 1) High relevance show source text
• San Carlos Zoning Code High relevance show source text
• San Carlos Zoning Code (Section numbers) High relevance show source text
• San Carlos Zoning Code (Section numbers) High relevance show source text
• San Carlos Zoning Code (Section 18.23.210.) High relevance show source text

Cited sections

• San Carlos Municipal Code — Rules of Measurement: **§ 18.03.050**, **§ 18.03.090**, **§ 18.03.100**, **§ 18.03.120** (figures and text on measuring height, FAR, lot coverage, and setbacks) . (§ 18.03.050)
• **§ 18.04.030** — Development Standards, Residential Single‑Family districts (**RS‑3**, **RS‑6**) (tables and notes) . (§ 18.04.030)
• **§ 18.04.050** — Development Standards, Residential Multi‑Family districts (**RM‑20**, **RM‑59**, **RM‑100**) (tables and transitional rules) . (§ 18.04.050)
• **§ 18.04.100** (Table 18.04.100‑G) — Development Standards, Small Lot Subdivision / Single‑Unit development (site FAR = **0.45**, **35%** lot coverage, setbacks, open space requirements) . (§ 18.04.100)
• **§ 18.05.030** — Mixed‑Use district development standards (density & commercial FAR tables) . (§ 18.05.030)
• **§ 18.06.030** — Commercial district development standards (**NR**, **GCI**, **LC**) . (§ 18.06.030)
• **§ 18.07.030** — Industrial district development standards (**IA**, **IL**, **IH**, **IP**) . (§ 18.07.030)
• **§ 18.08.030** — Public and Semi‑Public district standards (**P**, **PK**, **OS**) . (§ 18.08.030)
• **§ 18.09.030** and **§ 18.09.040** — Airport district land uses and development standards (height limits tied to the Airport Use Plan) . (§ 18.09.030)
• **§ 18.10.040** — Planned Development requirements (items a PD plan must address) . (§ 18.10.040)
• **§ 18.23.210** — Accessory dwelling unit development standards and state exemption cross‑references (ADUs) . (§ 18.23.210)
• **§ 18.33.020** — Administrative relief / waiver authority (dimensional waivers up to 10%) . (§ 18.33.020)
• Design review triggers and list of objective standards that require review: Chapter 18.29 referenced in the Code (see Design Review extracts) . (Chapter 18.29)
• Related City pages used for internal linking and applicant resources: San Carlos Zoning, San Carlos Parking, San Carlos Overlay Districts, San Carlos ADUs, San Carlos Landscaping and Screening, San Carlos Design Review, California Building Standards Code.
• SanCarlos_ZoningCode.md

• Official San Carlos code library