Marin County Zoning, Planning & Building Codes

Last reviewed: July 6, 2026

Overview

Marin County regulates land use only in the unincorporated areas. Two parallel codes apply: the countywide Development Code for inland areas (Title 22) and the Coastal Zoning Code for the Coastal Zone (Title 20), which is the County’s certified Local Coastal Program (LCP) Implementation Plan and controls in case of conflict in the Coastal Zone (§ 20.01.020; Chapters 20.60–20.70) . The Coastal Zoning Code lays out coastal districts, allowed uses, and coastal development standards (§ 20.62.010; § 20.64.010) . Title 22 continues to govern non-coastal procedures and permits (e.g., design review, use permits) even when a coastal project also needs a Coastal Development Permit (CDP), and the coastal code expressly cross-references those Title 22 processes (§ 20.62.040.B; § 20.62.040.C) .

The single most important orientation: if a parcel is in the Coastal Zone, the Coastal Zoning Code (Title 20) governs and a Coastal Development Permit is typically required in addition to any Marin County Title 22 approvals (§ 20.01.020; § 20.62.040.B) .

Use this page as a plain‑English map to Marin’s structure, districts, development standards, overlays, and the permit path—then jump to specifics via Marin County Zoning, Marin County Development Standards, Marin County Parking, Marin County Design Review, and Marin County Overlay Districts.

How Marin County’s code is organized

• Coastal Zone (Title 20 — Coastal Zoning Code / LCP Implementation Plan):
  • Applicability and coastal priority of the LCP (§ 20.01.020)
  • Coastal zoning districts and allowed uses (§ 20.62.010–.080)
  • Coastal site and resource standards (§ 20.64.010–.030; § 20.64.045)
  • Planned district standards (e.g., C‑APZ, C‑RSP, C‑RSPS) (§ 20.65.010–.070)
  • Community standards (community-specific provisions) (Chapter 20.66)
  • Coastal Development Permit procedures, Commission jurisdiction, findings (§ 20.68.080–.090; § 20.70.070)
  • Definitions (Chapter 20.130)
• Countywide (Title 22 — Development Code; inland areas and non-coastal procedures):
  • Official Zoning Map is adopted in Title 22 and is expressly referenced by the coastal code (§ 20.62.030 referencing § 22.06.030)
  • Design Review (Chapter 22.42), Use Permits (Chapter 22.48), Temporary Use Permits (Chapter 22.50), Permits and procedures (Chapter 22.62), Appeals (e.g., coastal appeals cross-referenced at § 22.70.080) — all cited within Title 20 tables/notes (§ 20.62.040.C; coastal tables)

Practical navigation: start by confirming whether the parcel is in the Coastal Zone; if yes, read Title 20 chapters above, then layer in any Title 22 process the coastal code cross-references. Otherwise, rely on Title 22 for zoning, design review, and procedures.

Zoning district families

Marin formalizes its coastal districts in four families; inland counterparts are in Title 22, but the coastal list is the most detailed and is controlling in the Coastal Zone:

• Agricultural/resource: C‑APZ, C‑ARP, C‑OA (§ 20.62.030; purposes in § 20.62.060.B; density note for C‑APZ: max 1 unit/60 acres)
• Residential: C‑RA, C‑R1, C‑RSP, C‑RSPS, C‑R2, C‑RMP (§ 20.62.030; purposes in § 20.62.070)
• Commercial/mixed-use: C‑VCR, C‑H1, C‑CP, C‑RMPC, C‑RCR (§ 20.62.030; purposes in § 20.62.080)
• Special purpose/combining: C‑PF and the coastal minimum lot size combining district –B (§ 20.62.030; § 20.62.090.C; § 20.64.040 reference)

Allowed uses and their permit levels (PP principal permitted; P permitted; U use permit) are presented in coastal tables with notes pointing to Title 22 procedures (§ 20.62.040; coastal Tables 5‑1, 5‑2, 5‑3) .

Citywide development standards

Marin implements development standards in both the coastal and inland codes. In the Coastal Zone:

• Property development and measurement rules (height, floor area ratio, site coverage) are centralized in § 20.64.045, and the coastal code directs readers there for calculations (§ 20.62.050.C) .
• General site prep and environmental protection standards include grading, drainage, vegetation, wildfire, and hazard siting (§ 20.64.030.H) .
• Community-specific and district-specific caps can be more restrictive: e.g., Tomales Bay height is 15 ft for new shoreline residences in C‑RSP (§ 20.65.060.C) and Seadrift has NAVD-based finished floor and total height limits in C‑RSPS (§ 20.65.070.D) .
• The coastal –B combining district sets minimum lot area, setbacks, heights, and FAR ranges (e.g., B1: 6,000 sf lot min; 25 ft front; 5 ft/10 ft sides; rear depth formula; 25 ft primary height; 0.30 FAR), with notes pointing to coastal height/setback exceptions and to Dillon Beach community standards (§ 20.64.045; § 20.66.110; Table 5‑5) .

Example coastal standard (–B combining district):

• The B1 standard set includes: minimum lot area 6,000 sf, front setback 25 ft, side setbacks 5 ft (standard)/10 ft (street side), maximum primary building height 25 ft, maximum accessory height 15 ft, and a maximum 0.30 FAR (Table 5‑5, notes cross‑refer to § 20.64.045) .

Countywide processes invoked by coastal projects:

• Design review occurs under Title 22 and applies in addition to CDPs per coastal table notes (see notes under coastal residential tables citing Chapter 22.42) (§ 20.62 residential Table 5‑2 notes) .
• Parking is required per coastal transportation standards and also per Marin’s countywide parking/loading provisions cross‑referenced to Title 24 (§ 20.32.023.K refers to §§ 24.04.330–.400) .
• Signs must satisfy both coastal and countywide signage rules (coastal standard plus Title 22 signage chapter, cited from § 20.32.023.I) and are best viewed via Marin County Signage (§ 20.32.023.I) .

Specific plans & overlays

• Community standards: The coastal code adds community‑level regulations (e.g., Dillon Beach) in Chapter 20.66 (note: the –B table sends you to § 20.66.110 for Dillon Beach) .
• Planned and site‑specific districts: Coastal planned districts carry bespoke standards, including C‑RSP along Tomales Bay (§ 20.65.060) and C‑RSPS in the Seadrift Subdivision (§ 20.65.070) .
• Combining/overlay tools: the coastal minimum lot size combining district –B modifies base district standards and ties into community standards (Table 5‑5; § 20.64.040 via references) — see Marin County Overlay Districts for orientation (§ 20.64.045 table notes) .

Building permits & review

• Coastal Development Permits: Unless exempt or categorically excluded, a CDP is required in the Coastal Zone (§ 20.62.040.B). Some projects fall under Coastal Commission jurisdiction (tidelands, submerged/public trust lands, certain state/federal facilities), or can be processed by a consolidated Commission CDP (§ 20.68.080; § 20.68.090) .
• CDP findings: Marin must make specific coastal findings addressing access, biological resources, hazards, water resources, community design, etc. (§ 20.70.070) .
• Parallel Title 22 approvals: Where the coastal code requires a Use Permit or design review, those are processed under Title 22 (e.g., Use Permits in Chapter 22.48; Temporary Use Permits in Chapter 22.50; design review in Chapter 22.42), and coastal tables/notes make those cross‑references (§ 20.62.040.C; coastal tables) .
• Zoning map & where to start: The official Zoning Map is adopted under Title 22 and is incorporated by reference into coastal zoning (§ 20.62.030 referencing § 22.06.030). Always confirm whether your site is in the Coastal Zone or inland before proceeding (§ 20.62.030) .
• Building permits: After land‑use approvals, projects proceed to building plan check under the California Building Standards Code; the coastal code repeatedly notes that coastal approvals are “in addition to” any Building Permit or other County approvals required (§ 20.62.040.B) .

State housing law in Marin County

• Accessory Dwelling Units: ADUs are a principal/permitted use across coastal residential districts, with a dedicated coastal ADU standard cited at § 20.32.140 (see coastal residential Table 5‑2) and must also align with state California ADU law (§ 20.62, Table 5‑2 entries) .
• Density bonus: The coastal code recognizes affordable housing as an allowed use (§ 20.32.080 listed in coastal Table 5‑2), but a local density bonus chapter was not surfaced in the retrieved materials; consult California housing laws and verify with the County (Not found in retrieved materials) .
• SB 9 lot splits/duplexes: A countywide SB 9 implementing section in Title 22 was not surfaced here; confirm current procedures with Marin Community Development Agency (Not found in retrieved materials).
• Tenant protections/rent limits: A countywide rent control chapter was not surfaced in the retrieved code; check County policy pages or applicable state law (Not found in retrieved materials).

Quick coastal standards snapshot (illustrative)

• The C‑APZ district caps residential density at a maximum of 1 unit per 60 acres and prioritizes agricultural use (§ 20.62.060.B.1; policy note in § 20.62.060.B; density statement) .
• Along Tomales Bay in C‑RSP, new residential height is limited to 15 ft (§ 20.65.060.C) .
• In Seadrift (C‑RSPS), finished floors and structure heights are tied to NAVD elevations, with specific maxima and FEMA interactions (§ 20.65.070.D) .

Source References

• Title 20 (Coastal Zoning Code / LCP): Applicability and implementation priority (§ 20.01.020; Chapters 20.60–20.70)
• Coastal zoning districts, allowed uses, and permit types (§ 20.62.010–.080; § 20.62.040; coastal tables)
• Coastal site/resource and property development standards (§ 20.64.010–.030; § 20.64.045)
• Planned district standards for C‑RSP and C‑RSPS (§ 20.65.060; § 20.65.070)
• Coastal –B combining district standards and Dillon Beach pointer (Table 5‑5; § 20.66.110 reference)
• CDP jurisdiction, consolidated permits, and findings (§ 20.68.080–.090; § 20.70.070)
• Cross‑references to Title 22 for design review, use permits, procedures (§ 20.62.040.C; coastal table notes; appeals at § 22.70.080 as cited)
• Parking and signage cross‑references (Title 24 parking; Title 22 signage) (§ 20.32.023.I, K)