Marin County — Historic Preservation

Last reviewed: July 6, 2026

Overview

This page explains how historic preservation is treated under Marin County’s local zoning/planning ordinance in the unincorporated areas, with a focus on the County’s certified Local Coastal Program (LCP) in Title 20 (Coastal Zoning Code) and its interaction with County development review. Start with the Marin County zoning & planning overview, then use this page to navigate when a building may be “historic,” what approvals are triggered, and how those approvals are evaluated in the coastal zone. Outside the coastal zone, related standards may live in Title 22 (Development Code), but those were not present in the retrieved materials (see Information Gaps).

The most important coastal rule: any demolition or substantial alteration/addition to a structure built before 1930 requires a Coastal Development Permit; routine in-kind repair consistent with the original architectural character is the exception. See § 20.68.060.F.

What counts as “historic” in Marin’s coastal code

• The LCP defines a “Historic Structure” as any building constructed prior to 1930, including accessory structures on the site, and treats these as “structures of special character and visitor appeal.” See § 20.130.030 (definitions) and § 20.68.060.F.
• Projects that involve pre-1930 buildings, mapped “historic areas,” or areas with “special character and visitor appeal” must be evaluated against the County’s Historical and Archaeological resources standards in § 20.64.160.
• For any Coastal Development Permit (CDP), the County must make a finding of consistency with the LCP’s historical/archaeological standards under § 20.70.070.L.

Approvals and review triggers in the coastal zone (Title 20)

• CDP required for pre‑1930 work. Demolition or substantial alterations/additions to any pre‑1930 structure require a CDP; routine maintenance/repair consistent with the original character and replacement-in-kind are not captured by this trigger. See § 20.68.060.F.
• Archaeological/paleontological due diligence. Where a site is in an area of known or likely archaeological or paleontological significance, a qualified field survey is required with appropriate mitigation, and construction monitoring can be required for sensitive sites. See § 20.64.160.A–B.
• Evaluation standards for historic character. CDP applications involving pre‑1930 buildings, mapped historic areas, or village areas with “special character and visitor appeal” must be evaluated for preservation/restoration of that character and for any proposed alterations or demolition. See § 20.64.160.B.3–7.
• Design Review layers. The LCP notes that Countywide design review is in Title 22, Chapter 22.42, and applies in addition to any CDP. See table notes citing Chapter 22.42. Use the Marin County Design Review page to navigate that process.

Where these rules apply

• The coastal rules above apply to all unincorporated properties in the Coastal Zone, administered under Title 20, which establishes the coastal zoning districts in § 20.62.030 and their regulations in § 20.62.040–.080.
• If your site is not in the Coastal Zone, consult Marin County Zoning and Marin County Development Standards; historic‑specific provisions for inland unincorporated areas were “Not found in retrieved materials.”

District-by-district context (coastal zones most affected by preservation)

The coastal zoning districts are established in § 20.62.030. All districts below remain subject to the historic triggers and standards summarized above whenever a pre‑1930 structure or mapped historic area is involved.

C‑VCR — Coastal, Village Commercial/Residential

• Purpose: Maintain the established historical character of village commercial areas and allow a balanced mix of resident- and visitor‑serving uses. See § 20.62.080.B.1.
• Typical permitted uses: Mixture of residential and commercial consistent with Table 5‑3 and § 20.62.040 (permit requirements vary). Verify with the jurisdiction.
• Key dimensional standards: Governed by coastal development standards in Chapter 20.64 and district provisions in § 20.62.080. Verify with the jurisdiction.
• Preservation note: Storefront remodels, signage, and façade changes in C‑VCR must respect village historical character and will be evaluated under § 20.64.160.B.3–7 and design review in Title 22. See Marin County Signage.

Coastal Residential Districts — C‑RA, C‑R1, C‑R2, C‑RSP, C‑RSPS, C‑RMP

• Purpose/uses: Residential districts with varying intensities, as listed in Tables 5‑2 (permit types vary by district/use). See § 20.62.040 and Table 5‑2 notes.
• Key dimensional standards: Setbacks, height, and FAR are in Chapter 20.64 (e.g., projections into setbacks, height measurement). See also community standards in Chapter 20.66 where mapped.
• Preservation note: Any work affecting a pre‑1930 cottage or accessory structure triggers § 20.68.060.F and must meet § 20.64.160 evaluation standards; routine in-kind maintenance remains exempt from this historic CDP trigger.

Coastal Commercial/Mixed‑Use Districts — C‑H1, C‑CP, C‑RMPC, C‑RCR

• Purpose/uses: Highway‑serving, planned, residential/commercial multiple planned, and resort/commercial recreation districts, respectively; see § 20.62.080.
• Key dimensional standards: Governed by Chapter 20.64 and district provisions. Verify site‑specific standards.
• Preservation note: If a pre‑1930 building is involved, the CDP trigger applies per § 20.68.060.F, and alternatives/demolition are evaluated under § 20.64.160.B.5–7.

Coastal Agricultural/Resource Districts — C‑APZ, C‑ARP, C‑OA

• Purpose/uses: Protect agricultural lands and open areas; see § 20.62.060 for intent and standards.
• Preservation note: Bars, barns, or farmhouses built before 1930 are “historic structures” for CDP purposes; demolition or substantial alteration/addition triggers § 20.68.060.F. Archaeological review often applies in rural areas per § 20.64.160.A–B.

Special Purpose & Combining — C‑PF and Coastal “‑B” Minimum Lot Size

• Purpose: Public facilities (C‑PF) and minimum lot size combining districts (“‑B”) to tailor lot, setback, or community standards. See § 20.62.030 and § 20.64.040 (‑B).
• Preservation note: Historic triggers apply if pre‑1930 buildings are on site; development must also respect any mapped community standards under Chapter 20.66. See Marin County Overlay Districts.

How coastal preservation standards are applied

• CDP findings must address historical/archaeological consistency under § 20.70.070.L, in addition to other LCP resource findings.
• Submittals may require:
  • A qualified archaeological or paleontological field survey and recommended mitigation/avoidance if resources are likely, per § 20.64.160.A–B.1.
  • Construction monitoring on archaeologically sensitive sites, per § 20.64.160.B.2.
• In mapped “historic areas” or “village areas with special character,” new construction must maintain that character, per § 20.64.160.B.7. Coordinate early with Marin County Land Use.

Related processes that commonly overlap

• Design changes almost always implicate Marin County Design Review; Title 22 Design Review applies in addition to any CDP. Table notes in the LCP explicitly point applicants to Chapter 22.42.
• Development standards (height, setbacks, FAR) live in Marin County Development Standards and Chapter 20.64; signage changes may require Marin County Signage approvals—important for historic storefronts.
• Parking/streetscape changes in historic villages can affect character and coastal access; check Marin County Parking and coastal access policies as applicable.
• If a historic building is also nonconforming, see Marin County Nonconforming Uses and Marin County Variances and Exceptions. Verify with the jurisdiction.
• ADUs are generally allowed but local standards may prevent adverse impacts to properties listed on the California Register; see California ADU law and HCD’s 2025 guidance. Not a Marin ordinance, but relevant state law context.
• Construction code alternatives for historically designated buildings live in the California Building Standards Code (California Historical Building Code). This is building‑code, not zoning; coordinate with the Building Division. Not analyzed here.

Key triggers and standards at a glance

Checklist

• Confirm whether the site is in the Coastal Zone under Title 20 and note the applicable coastal district from § 20.62.030.
• Determine if any on‑site structure was built before 1930; if yes, plan for a CDP per § 20.68.060.F.
• Screen for mapped “historic areas” or “village areas with special character and visitor appeal”; if applicable, prepare materials addressing § 20.64.160.B.3–7.
• If in an area of known/likely archaeological resources, retain a qualified archaeologist/paleontologist and include the required field survey and mitigation plan per § 20.64.160.A–B.
• Prepare designs that also satisfy Title 22 Marin County Design Review (applies in addition to any CDP).
• Cross‑check other affected standards (setbacks, height, parking, signage, landscaping) to avoid conflicts with historic character.
• If proposing an ADU on or near a listed historic resource, ensure local standards are objective and avoid adverse impacts (state ADU law context).
• Build a findings memo aligning the project with § 20.70.070.L (Historical & Archaeological Resources) and other applicable LCP findings.

Risks & Ambiguities

Information Gaps

• Historic preservation provisions in inland unincorporated areas under Title 22 (Development Code): Not found in retrieved materials.
• Official County register/listing process for local landmarks outside the LCP: Not found in retrieved materials.
• Definitive maps of “historic areas” and “village areas with special character and visitor appeal” under the LUP/LCP: Not found in retrieved materials.

Plain-English Summary

If your place is in unincorporated coastal Marin and was built before 1930, you’ll likely need a Coastal Development Permit for anything beyond basic in‑kind repairs. The County will look at how your project preserves historic character and addresses archaeology, and you’ll also go through County Design Review. Check your district standards, prepare the right studies, and line up your evidence so the County can make the required findings.

Source References

• Marin County LCP — Historical & Archaeological Resources standards: § 20.64.160.
• Marin County LCP — CDP required; pre‑1930 demolition/major alteration trigger: § 20.68.060.F.
• Marin County LCP — CDP findings for Historical/Archaeological Resources: § 20.70.070.L.
• Marin County LCP — Definitions (“Historic Structure,” “Historic Public Use”): § 20.130.030.
• Marin County LCP — Coastal zoning districts established: § 20.62.030.
• Marin County LCP — Coastal commercial/mixed‑use (C‑VCR purpose: maintain historical character): § 20.62.080.B.1.
• LCP table notes — Design Review is in Title 22, Chapter 22.42, and applies in addition to CDP: table note in coastal district tables.
• Marin County LCP — Community Standards (purpose): § 20.66.010.
• State ADU law context (ministerial ADUs and historic resources): HCD 2025 ADU Handbook.

Retrieved passages

• Marin County Zoning Code (§ III) Medium relevance show source text
• Marin County Zoning Code (Chapter 20.130) Medium relevance show source text
• Marin County Zoning Code (Section 20.65.070.D) Medium relevance show source text
• Marin County Zoning Code (Section 20.32.024) Medium relevance show source text
• Marin County Zoning Code (§ 65915) Medium relevance show source text
• Marin County Zoning Code (Section 20.32.100) Medium relevance show source text
• Marin County Zoning Code (Section and) Medium relevance show source text
• Marin County Zoning Code (Section 22.82.050) Medium relevance show source text
• Marin County Zoning Code (§ III) High relevance show source text
• Marin County Zoning Code (§ III) Medium relevance show source text
• Marin County Zoning Code (title to) Medium relevance show source text
• Marin County Zoning Code (section of) Medium relevance show source text
• Marin County Zoning Code (§ III) Medium relevance show source text
• Marin County Zoning Code (Title 20) Medium relevance show source text
• Marin County Zoning Code (§ III) Medium relevance show source text
• Marin County Zoning Code Medium relevance show source text
• Marin County Zoning Code (Section 22.82.050) Medium relevance show source text
• Marin County Zoning Code (Chapter 20.62) Medium relevance show source text
• Marin County Zoning Code (title to) Medium relevance show source text
• Marin County Zoning Code (§ III) Medium relevance show source text
• Marin County Zoning Code (§ III) Medium relevance show source text
• CBC § 18954 (Section 18954) Medium relevance show source text

Cited sections

• Marin County LCP — Historical & Archaeological Resources standards: **§ 20.64.160**. (§ 20.64.160)
• Marin County LCP — CDP required; pre‑1930 demolition/major alteration trigger: **§ 20.68.060.F**. (§ 20.68.060.F)
• Marin County LCP — CDP findings for Historical/Archaeological Resources: **§ 20.70.070.L**. (§ 20.70.070.L)
• Marin County LCP — Definitions (“Historic Structure,” “Historic Public Use”): **§ 20.130.030**. (§ 20.130.030)
• Marin County LCP — Coastal zoning districts established: **§ 20.62.030**. (§ 20.62.030)
• Marin County LCP — Coastal commercial/mixed‑use (C‑VCR purpose: maintain historical character): **§ 20.62.080.B.1**. (§ 20.62.080.B.1)
• LCP table notes — Design Review is in Title 22, Chapter 22.42, and applies in addition to CDP: table note in coastal district tables. (Title 22)
• Marin County LCP — Community Standards (purpose): **§ 20.66.010**. (§ 20.66.010)
• State ADU law context (ministerial ADUs and historic resources): HCD 2025 ADU Handbook.
• MarinCounty_ZoningCode.md
• 2025 California ADU handbook.md

• Official Marin County code library