Local zoning · San Mateo

San Mateo — Zoning

Q: What are the C‑3 district FAR and height limits?

The C3 district sets maximum floor area ratios of 1.0 (C3‑1) and 2.0 (C3‑2) as specified in § 27.34.050 , while building height limits are controlled by the General Plan Building Height Plan referenced in § 27.34.055 ; parking must comply with Chapter 27.64 per § 27.34.040 .

Zoning under the San Mateo local zoning and planning code, with the controlling citations.

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Last reviewed: July 2, 2026

Overview

San Mateo's zoning rules are codified in the City Zoning Code (Title 27 of the Municipal Code) and are organized by base residential and commercial districts, plus special plan and overlay districts (TOD, Downtown, Qualified “Q” overlays, Senior Citizen “SC”, and others). Use, dimensional controls (setbacks, yards, FAR, height), and review paths (administration, SPAR, special permits) are set out across multiple chapters; applicants must always check the zoning map on file with the City Clerk to determine a parcel’s district before relying on standards. See the City’s zoning & planning overview for context and maps. San Mateo zoning & planning overview

How to read this page

Every requirement below is tied to the cited local ordinance section (§). File excerpts used are from the City Zoning Code (Title 27) as provided; citations show the controlling § and the uploaded file reference. Verify parcel-specific rules with the City (zoning map and staff) before designing a project.

District-by-district breakdown

Note: Each district name below is the City’s zoning designation in Title 27. For permitted uses and precise numeric dimensional tables, consult the cited section for that district and the zoning map on file with the City Clerk (§ 27.82.010).

### R-1 (Single-Family Residential)

Purpose: Standard single-family residential district; controls intended to protect single-family character and scale. See the minimum development and yard rules in the R1 chapter. Front, side and rear yards and allowable projections are defined in the R1 chapter. ◆ See § 27.18.090 for rear yard minima and § 27.18.100 for permitted yard projections.
Typical permitted uses: Single-family dwellings and accessory uses (see R1-specific permitted-uses section in Title 27). Not all accessory uses are identical citywide—verify with the Zoning Administrator.
Key dimensional notes: Rear yard minimum 15 ft (and 25 ft where new construction exceeds one story) per § 27.18.090. Eaves, small balconies, and low decks have express projection allowances under § 27.18.100.
Where it applies: See the official zoning maps filed with the City Clerk (§ 27.82.010).

### R-2 (Two-Family Residential)

Purpose: Allows duplexes and accessory residential uses where compatible with surrounding single-family areas. See Chapter 27.20.
Typical permitted uses: All uses permitted in R-1 plus two-family dwellings and accessory uses (§ 27.20.010).
Key dimensional standards: The chapter sets building and lot controls and specifically limits the number of residential buildings on a zoning plot (§ 27.20.030). Off-street parking is required per the parking chapter referenced in the R2 rules.
Where it applies: See city zoning maps (§ 27.82.010).

### R-3, R-4, R-5, R6-D (Higher-density residential / Mixed)

Purpose: Mid- to higher-density residential districts and density-overlay variants used for multifamily and mixed uses; the City also applies a /R residential overlay in downtown areas to modify density, height and FAR. See the Residential Overlay chapter for density rules.
Typical permitted uses: Multifamily residential, mixed-use where allowed; the overlay may limit where residential is permitted at ground floor (e.g., Downtown Specific Plan restrictions). See § 27.29.104 and related overlay subsections.
Key dimensional standards: Overlay density caps (for example, /R4, /R5 densitiy and FAR limits) are set in § 27.29.106–27.29.112; the overlay specifies minimum parcel areas, maximum coverage, and FAR differences from underlying zones.
Where it applies: Locations and restrictions are identified in the zoning map and the Downtown Specific Plan references. Verify with the zoning map and General Plan when conflicts arise (§ 27.02.170 on General Plan conformance).

### C-1, C-2, C-3 (Commercial districts; example: C3)

Purpose: Serve neighborhood to regional commercial needs; C3 intended for major commercial centers (broader allowed uses than C2). See Chapter 27.34 for the C3 district.
Typical permitted uses: Retail, office, services; C3 explicitly permits vehicle sales and rentals, car washes (limited), labs without on-site production, and accessory uses where noted (§ 27.34.010). Special uses (drive-thrus, large assembly uses) require a special-use permit (§ 27.34.020).
Key dimensional standards: FAR caps such as 1.0 for C3-1 and 2.0 for C3-2; building heights are governed by the General Plan Building Height Plan (§ 27.34.050–27.34.055). Off-street parking and loading are required per Chapter 27.64 as referenced in § 27.34.040.
Where it applies: See zoning map and any site-specific Qualified (Q) overlays that alter standards.

### CBD / E / TOD / Rail Corridor (Transit-Oriented)

Purpose: Downtown CBD/E and Transit-Oriented Development districts encourage higher intensity mixed-use and transit-supportive development. The Rail Corridor Plan and Hillsdale Station Area Plan overlay TOD standards on underlying zones. See Chapters 27.90 and 27.92.
Typical permitted uses: Uses are those allowed in the applicable base zoning district, subject to the Rail Corridor Plan’s specific allowances (Chapter 27.90.030). Special uses that are substantially similar can be permitted via special use permit (§ 27.90.040).
Key dimensional standards: Rail Corridor and Station Area chapters require projects to comply with plan-specific setbacks, heights, FAR, parking/TDM, and open space rules (see § 27.90.050–27.90.060 and § 27.92.050).
Where it applies: Boundaries are shown on the Rail Corridor and Hillsdale Station maps contained in those chapters; these plans control where they conflict with the Zoning Code (§ 27.90.070).

### Two-Unit / SB 9 Overlay (Two-Unit Development / Urban Lot Splits)

Purpose: Implements state SB 9 and a local Two-Unit Development Overlay to allow up to two primary dwelling units on qualifying single‑family parcels and urban lot splits under objective standards (§ 27.21.010, Article I and II).
Typical permitted uses: Adds limited allowances for a second unit or lot split subject to objective standards, deed restriction requirements, and other conditions (§ 27.21.010, § 27.21.040, § 27.21.050, § 27.21.100).
Key dimensional standards:
- Side and rear setbacks for SB 9 units: 4 ft minimum (with specific exceptions for conversions) (§ 27.21.* — see SB 9 Article text in Title 27).
- Height limits for two-unit overlay: attached max 24 ft (plateline) / 32 ft (roof peak) and detached 16 ft / 24 ft (roof peak) where applicable (per the overlay standards).
- Parking: One off-street parking space per SB 9 unit is required unless exemptions apply (e.g., within 1/2 mile of high-quality transit or a major transit stop) (§ 27.21 provisions).
Where it applies: Only on parcels zoned for single-family that meet the overlay criteria; some R1‑subtypes (R1-A, R1-B, R‑C) are explicitly excluded (§ 27.21.050).

### SC (Senior Citizen Overlay)

Purpose: Encourages senior housing where appropriate by allowing development under SC regulations while retaining the underlying base zone; an SC-zoned plot may be developed under either the underlying zone or SC standards if authorized by a special use permit (§ 27.61.010–27.61.030).
Typical permitted uses: Senior citizen housing as a special use subject to criteria in § 27.61.040; SC may be superimposed only on specified zones (R3, R4, R4D, R5, R5‑D, R6‑D, C, E, TOD) (§ 27.61.020).

### Qualified “Q” Overlays and Site-Specific Conditions

The City uses Qualified (Q) overlay classifications (e.g., Q6, Q7, Q8) to place site‑specific development conditions, caps on FAR, parking rules, required master plans and special permit requirements; each Q overlay lists its conditions and FARs (examples: Q7 FAR 0.31, Q8 FAR 0.39) (§ 27.29 subsections and Q statements).

Key decision-relevant table (high-level)

District / Topic	Typical permitted uses	Most decision-relevant standard(s)	Code Reference
R-2	Duplexes; R-1 uses	Limits on number of residential buildings per zoning plot; parking per Ch. 27.64	§ 27.20.010, § 27.20.030
R-1	Single-family + accessory	Rear yard 15 ft (new >1 story 25 ft); yard projection rules	§ 27.18.090–27.18.100
C-3	Regional commercial (retail, office, service)	FAR 1.0 (C3‑1) / 2.0 (C3‑2); heights per General Plan; parking per Ch. 27.64	§ 27.34.010, § 27.34.050–27.34.055
TOD / Rail Corridor	Mixed‑use, transit‑oriented	Apply Rail Corridor Plan standards (density, parking/TDM, setbacks)	§ 27.90.030–27.90.060
Two-Unit Overlay / SB 9	Up to two primary units; lot splits	Side/rear 4 ft setbacks for SB9 units; 1 parking space per SB9 unit (with exemptions)	Title 27, Two‑Unit Article (Article I & II) § 27.21.010 et seq.
SC overlay	Senior housing (by special permit)	SC applies only to listed underlying zones; special permit criteria	§ 27.61.010–27.61.040

Practical guidance & quick comparisons (plain-English)

Before design work, confirm the parcel’s official zoning map designation (maps are incorporated into Title 27 and are on file with the City Clerk) (§ 27.82.010–27.82.020).
Use tables above to screen whether a use is likely permitted by right (e.g., duplex in R-2), or will need a special use permit or site plan and architectural review (SPAR) (§ 27.08.030).
Projects in commercial districts must reconcile underlying district standards with any site-specific Q overlay caps (especially FAR and parking) — find Q overlay language in the district chapter where the property is listed (§ 27.29 Q-subsections).
Parking requirements are handled in the parking chapter and are cross‑referenced throughout the zoning chapters; plan parking early because some overlays or TOD rules substantially alter requirements (§ 27.34.040 references Chapter 27.64). San Mateo Parking
Design review: many projects require Site Plan and Architectural Review (SPAR) or local design-board review; SPAR findings and the required submittal package are in § 27.08.030 and related application rules. San Mateo Design Review
Development standards (setbacks, yards, projections, FAR, coverage) appear in the base‑zone chapters and special plan chapters — consult the Development Standards guidance and the zone chapter for the parcel. San Mateo Development Standards
Accessory Dwelling Units (ADUs) / JADUs are governed by separate Title 27 chapters with their own rules (size, parking, deed restriction, owner-occupancy in some JADU cases). See the ADU chapter for the city’s local rules and state ADU law interplay. San Mateo ADUs California ADU law

Checklist

Confirm parcel zoning on the official City zoning map on file with the City Clerk (§ 27.82.010–27.82.020).
Read the base‑zone permitted uses and special uses for that district (e.g., § 27.20.010 for R‑2; § 27.34.010 for C‑3).
Check overlays and plan chapters that apply (Two-Unit Overlay, /R overlay, Q overlays, TOD, Hillsdale) and their effect on density, FAR, and height (§ 27.21, § 27.29, § 27.90, § 27.92).
Confirm dimensional standards: setbacks, yards, maximum height and FAR in the zone chapter (examples: § 27.18.090 for R1 rear yard; § 27.34.050 for C3 FAR).
Prepare materials required for SPAR or other planning review (plans, site diagrams, deed/title documents) per the planning application requirements and § 27.08.030 guidance. San Mateo Design Review
Calculate parking per Chapter 27.64; evaluate exemptions (e.g., SB9 exemptions near transit) where applicable (§ 27.21 SB9 rules and § 27.34.040 references). San Mateo Parking
If a discretionary variance, rezoning, or special use is needed, prepare findings and neighborhood noticing per Chapters 27.78 (variances) and 27.08 (reclassification, amendments).

Risks & Ambiguities

Issue	Why it matters	What to verify
Zoning map boundary uncertainty	Boundaries on the official map can be ambiguous at centerlines, lot lines, vacated streets — this changes which zone's rules apply (§ 27.82.020).	Confirm exact boundary with City staff and the official map; if disputed, an appeal can be filed per § 27.82.020(e).
Overlay vs. underlying zone conflicts	Overlays (Q, /R, SC, TOD) may supersede or change base-zone standards (FAR, allowed uses) — failing to check overlays leads to incorrect assumptions about allowed density and height (§ 27.29, § 27.90).	Verify all overlays that apply to the parcel on the zoning map and read overlay text (Q sub‑sections and /R rules).
SB 9 / Two‑Unit exceptions & state interplay	SB 9 local implementation includes state-mandated exemptions and local objective standards; missing an SB 9 exception (e.g., parcel type or historic constraints) can cause denial (§ 27.21).	Confirm SB 9 eligibility and specific local objective standards; check deed restrictions and short‑term rental prohibitions required by § 27.21.040.
Parking counts vs. Transit exemptions	Parking requirements may be reduced or waived near transit, but the local code ties exemptions to statutory definitions (high‑quality transit / major transit stop) — misapplying an exemption may lead to later deficiency. (§ 27.21 parking exemptions).	Confirm transit proximity against statutory definitions and City maps; compute spaces per Chapter 27.64. San Mateo Parking
Project-specific Q overlay conditions	Q overlays often carry site-specific master plan or onsite parking conditions (e.g., maximum off-site parking distance) that override generic standards (§ 27.29 Q6–Q8 examples).	Read the exact Q overlay text for the parcel; verify any Council resolutions or planning application conditions cited.

Plain-English Summary

San Mateo’s zoning (Title 27) divides the city into base residential and commercial zones that set uses, yards, height and FAR rules, and then layers plan or site-specific overlays (TOD, /R, Q, SC). Always confirm your parcel’s map designation, read the base-zone chapter and any overlay language, and prepare for SPAR or special-permit pathways when a proposed use or dimension is not allowed outright (§ 27.82.010, § 27.08.030).

Source References

Title 27 — City Zoning Code (selected excerpts used in this page): § 27.34.010–27.34.060 (C3 district permitted uses, FAR, height and parking cross‑reference).
Title 27 — Definitions and Zoning maps: § 27.04.005, § 27.04.495 (yards), § 27.04.500 (zoning maps).
Administration — Approval bodies, Zoning Administrator duties: § 27.06.010–27.06.020.
Site Plan & Architectural Review (SPAR) requirements and findings: § 27.08.030.
R‑1 development rules (yards, projections): § 27.18.090–27.18.100.
R‑2 district: permitted uses and building limits: § 27.20.010–27.20.030.
Two-Unit Development / SB 9 implementation (Article I & II): § 27.21.010 and related Article sections (setbacks, parking, deed restrictions, exemptions).
Residential overlay and Downtown-specific rules (density, FAR, coverage): § 27.29.104–27.29.112.
Qualified overlays / site-specific Q conditions (examples Q6, Q7, Q8): Q subsections within Title 27 chapters (see Q6–Q8 descriptors and FAR caps).
Rail Corridor / TOD and Hillsdale Station Area Plan: § 27.90.030–27.90.070, § 27.92.010–27.92.050.
Zoning Maps and boundary rules: § 27.82.010–27.82.020.
Variances (criteria and purpose): § 27.78.010–27.78.020.

Sources

Retrieved passages

San Mateo Zoning Code (Chapter 27.24) High relevance
CFC § 65589.5 (Section 65589.5) High relevance
San Mateo Zoning Code (Title 27) High relevance
San Mateo Zoning Code (title designating) High relevance
San Mateo Zoning Code (Chapter 27.74) High relevance
San Mateo Zoning Code (Section 27.08.030) High relevance
San Mateo Zoning Code (Title and) High relevance
San Mateo Zoning Code (section shall) High relevance

Cited sections

Official San Mateo code library

Frequently asked questions

What can I build on an R-1 lot in San Mateo?

You may generally build a single-family dwelling and customary accessory uses; dimensional controls (front/side/rear yards and allowable projections) are set in the R1 chapter — see the yard rules in § 27.18.090–27.18.100 for setbacks and which projections are permitted. Confirm permitted accessory uses and any overlay applicability on the parcel with the City.

What are San Mateo setback requirements for single‑family homes?

Setbacks vary by zone and specific lot; for example, the R1 rear-yard minimum is 15 ft (and 25 ft for new construction above a single story) per § 27.18.090, and § 27.18.100 lists allowed yard projections. Always check the zone chapter that applies to your parcel.

Do I need Site Plan and Architectural Review (SPAR) in San Mateo?

Many projects (new buildings, parking lots, fences >7 ft, additions and certain alterations) require SPAR before construction; SPAR rules, criteria and required findings are in § 27.08.030. Some minor single‑family work that conforms to Chapter 27.18 standards may be exempt — verify with planning staff.

How does the City treat zoning map boundary disputes?

Zoning district boundaries are shown on the official zoning maps filed with the City Clerk and are incorporated into the code (§ 27.82.010). Where boundaries are uncertain, rules in § 27.82.020 explain how centerlines, lot lines and split parcels are interpreted; disputes can be appealed per that chapter.

Where does the Two‑Unit / SB 9 overlay let me add a unit or split a lot?

Title 27’s Two‑Unit Development Article implements SB 9 and sets the objective standards for adding up to two primary units or doing an urban lot split (Article I & II, § 27.21.010 et seq.). The overlay specifies eligible parcels, 4‑ft side/rear setbacks for SB9 units (with conversion exceptions), height caps, parking rules and deed restrictions — read the Article carefully for exceptions and exclusions.

What are the C‑3 district FAR and height limits?

The C3 district sets maximum floor area ratios of 1.0 (C3‑1) and 2.0 (C3‑2) as specified in § 27.34.050, while building height limits are controlled by the General Plan Building Height Plan referenced in § 27.34.055; parking must comply with Chapter 27.64 per § 27.34.040.

When do I need a special use permit in commercial zones?

Uses listed as “special uses” in a district (for instance, some assembly uses, drive‑thru restaurants in C3) may be allowed only via a special use permit; see district special-use lists (e.g., § 27.34.020 for C3) and the special‑use permit procedures in Title 27.

Does the Rail Corridor / TOD override the Zoning Code?

The Rail Corridor Plan and TOD chapter may control in case of conflict with the Zoning Code; § 27.90.070 states that the Rail Corridor Plan governs where terms conflict with Title 27, and the Rail Corridor Plan itself sets development guidelines (density, off‑street parking, TDM, setbacks).

Are there site‑specific “Q” overlays that change the rules for a parcel?

Yes — Q overlays are site‑specific qualifiers that can require special permits, establish FAR caps, parking location rules, and master-plan compliance (examples Q6–Q8 with their specific FARs and conditions are in Title 27 text for affected sites). Always read the local Q overlay text for a parcel.

Where do I find the City’s official zoning map?

The zoning maps incorporated into Title 27 are on file with the City Clerk, and Title 27 explains how to interpret boundary lines and resolve uncertainties (§ 27.82.010–27.82.020). Confirm the parcel’s zoning by contacting the City Clerk or the Department of Community Development. ---

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