Local zoning · Humboldt County

Humboldt County — Historic Preservation

Q: Do I need design review for work on a historic house in unincorporated Humboldt County?

If your property lies in a D Zone or in a special plan area (for example Samoa or Scotia) then yes — design review (and a Special Permit for D-zone work) will be required (§ 19.1.2–.3; § 19.1.9). If a local Design Review Committee is not appointed, the Planning Director will require a Historic Assessment Report and act in place of the committee (§ 19.1.4.1.2).

Q: Can the County block demolition of a County-designated historic structure?

Yes. Once a structure is designated a County historical structure , exterior alteration or demolition is restricted; the Board can delay demolition, require documentation, and pursue alternatives (acquisition, relocation) during the delay period (§ 71.1.3.1–.3). Normal maintenance is allowed without prior design-review approval (§ 71.1.3.1).

Q: What standards will the County use to judge alterations or rehabilitation?

The County explicitly applies the Secretary of the Interior’s Standards and Guidelines and the Department of Interior’s Standards of Rehabilitation , together with the State Historical Building Code and local Samoa/Scotia Design Guidelines where applicable (§ 19.1.4.1.2.1; § 19.1.9.3.3.3).

Historic Preservation under the Humboldt County local zoning and planning code, with the controlling citations.

Ask a question free See coverage

Last reviewed: July 3, 2026

Overview

This page summarizes how historic preservation is handled in the Humboldt County zoning/planning ordinance for the county’s unincorporated areas. Key tools are the D (Design Control) combining zone, special local design-review committees (notably Samoa and Scotia), a County historic-structure designation program, and procedural requirements (historic-assessment reports, demolition limits, and standards to follow). All standards below are drawn from the Humboldt County Code; verify parcel-specific application with County staff. § citations and local-code excerpts are provided.

How Humboldt County regulates historic resources (quick roadmap)

Design-review overlay: D Zone (Design Control Combining Zone) — design review and special permit required for lands shown “D” on the zoning map (§ 19.1).
Local townsite design-review committees: Samoa Design Review Committee and Scotia Design Review Committee — review and recommendations for contributing historic structures (§ 19.1.4; § 19.1.9.3).
County designation and protection: County historical structures program — Board of Supervisors may designate structures and limit exterior change or demolition (§ 71.1).
Project-level studies and minimum thresholds: Historic Assessment Reports required when committee absent or for projects affecting older structures; specific content and professional qualifications apply (§ 19.1.4.1.2; § 55.4.12.1.14).

Note on related technical rules: the County bases its preservation review on the Secretary of the Interior’s Standards and the State Historical Building Code; technical building-code compliance and life-safety design remain governed by the California Building Standards Code (Title 24). Link: California Building Standards Code. (/us/california/building-codes)

District-by-district breakdown (what applies where)

D Zone (Design Control Combining Zone)

Purpose: The D Zone is a combining zone used to preserve or enhance areas of historical, scenic, civic, or cultural value; it is combined with underlying principal zones so design controls apply in addition to the base zone (§ 19.1).
Typical permitted uses: Uses allowed are those of the underlying principal zone; the D overlay imposes an additional review process (design review / special permit) rather than changing base permitted uses (§ 19.1.1–19.1.3).
Key procedural standard: A Special Permit is required for all development subject to D-zone regulations (§ 19.1.3.1).
Where it applies: Lands shown “D” on the County Zoning Maps; when you see D on your zoning map the combining standards and the special-permit requirement apply (§ 19.1.2).
Design controls / dimensional hints: The D regulations include detailed design controls (e.g., minimum roof overhang 12 in.) and material limitations; these are implemented by design review when applicable (§ 19.1.8.1.3–.4).

Practical note: Because D is a combining zone, permitted uses and dimensional standards (setbacks, lot coverage) still come from the underlying zone and the County’s development standards — see Humboldt County Development Standards. (/us/california/humboldt-county/development-standards)

Samoa design-review area and standards (Samoa townsite)

Purpose & scope: The County has dedicated design-review rules tailored to the Samoa townsite and its historic character; the Samoa Design Review Committee (SDRC) reviews contributing historic structures and project compatibility (§ 19.1.4; § 19.1.9).
Typical permitted uses: Uses follow the underlying Humboldt Bay Area Plan and base zoning; however, alterations or demolition of contributing structures in Samoa trigger additional review and possible conditions (§ 19.1.9.1–.3).
Key standards and review requirements:
- No contributing historic structure may be altered or demolished without County approval (§ 19.1.9.1.3).
- If an SDRC is not appointed, the Planning Director will require a Historic Assessment Report prepared by a professional historic resources consultant following the Secretary of the Interior’s Standards (§ 19.1.4.1.2).
- For demolition within Samoa the County may delay or condition demolition and may require replacement development to match scale/character or retain/reconstruct facades (§ 19.1.9.1.2.3–.4).
Where it applies: Samoa portions of the Humboldt Bay Area Plan (maps and special plan text trigger these provisions) (§ 19.1.9).

Practical note: Samoa review explicitly uses the Secretary of the Interior’s Standards and the State Historic Building Code as the normative criteria for evaluating changes (§ 19.1.4.1.2.1).

Scotia design-review area and standards

Purpose & scope: The Scotia Design Review Committee has a similar role for the Scotia townsite — reviewing alterations and demolitions of contributing structures and recommending consistency with Scotia Design Guidelines (§ 19.1.9.3.1).
Typical permitted uses: Base-zone uses remain, but significant exterior changes for contributing structures require review and potentially conditions (§ 19.1.9.3.3.3).
Key standards: If the local committee is absent, the Director requires a Historic Assessment Report with the content/qualification standards specified in the code (maps, background literature search, description, recommendations) (§ 19.1.9.3.2.1–.2.2).

County Historical Structures (Chapter 71.1)

Purpose: Provides the process for the Board of Supervisors to designate County historical structures and to protect them in the unincorporated areas (§ 71.1.1–.2).
What designation does: After designation, no County historical structure may be demolished or have its exterior appearance changed except under the narrow exceptions and review described in the chapter (§ 71.1.3).
Exceptions: Normal repair and maintenance is allowed without design-review approval; exterior alterations are limited and subject to design review; the Board may delay demolition and seek alternatives (§ 71.1.3.1–.3).
Parcel-size flexibility: The code allows exceptions to minimum parcel size for preservation of County-designated historic structures or State/Federal-listed buildings, subject to conditions (e.g., no adverse impact to agriculture) (§ 71.1.4).

Project-level triggers (other chapters)

Structures over 45 years old: Projects that remove or alter structures over 45 years old must submit a historic report prepared by a consultant meeting Secretary of the Interior professional qualifications; the report must evaluate eligibility for local/state/federal registers and propose mitigation if needed (§ 55.4.12.1.14).
Archaeology: Ground-disturbing projects may trigger archaeological excavation plans prepared by qualified archaeologists (§ 16.2.5.6).

Decision‑relevant standards & quick reference table

Topic	Key rule / limit	Code reference
Design-review combining zone applicability	Lands designated “D” require design review; Special Permit required for development under D (§ 19.1.2–.3)	§ 19.1.2; § 19.1.3
Samoa historic review standard	No contributing structure altered/demolished without County approval; SDRC follows Secretary of the Interior’s Standards	§ 19.1.9.1.3; § 19.1.4.1.2.1
Scotia review requirement	Scotia DRC reviews contributing structures; Historic Assessment Report required if committee absent	§ 19.1.9.3.1; § 19.1.9.3.2.1–.2.2
County designation authority	Board of Supervisors may designate County historical structures; exterior changes restricted	§ 71.1.2–.3
Demolition controls / delay	County can delay demolition up to 90 days and impose conditions; replacement scale/facade requirements in Samoa	§ 19.1.9.1.2; § 71.1.3; § 19.1.9.1.2.3–.4
Historic Assessment Report contents	Background sources, field inventory, maps, evaluation, mitigation recommendations, consultant qualifications per 36 CFR Part 61	§ 19.1.4.1.2.2; § 19.1.4.1.2.2.8
Threshold for special historic review in other chapters	Projects involving removal/exterior alteration of structures >45 years need a historic consultant report (§ 55.4.12.1.14)	§ 55.4.12.1.14

Practical guidance (how to approach a preservation project in unincorporated Humboldt County)

Check the parcel zoning map for a D overlay and for plan-area overlays (Samoa, Scotia). If your parcel shows D or lies in Samoa/Scotia, plan for design review and hold a pre‑application meeting. Verify overlay status with Planning staff — Verify with the jurisdiction. (§ 19.1.2; § 19.1.9).
If work will remove or alter a building over 45 years old, budget for a Historic Assessment Report by a consultant meeting Secretary of the Interior standards (see report contents & professional-qualification reference) (§ 19.1.4.1.2.2; § 55.4.12.1.14).
Follow the Secretary of the Interior’s Standards and the State Historical Building Code where the ordinance requires it — County review will use these as the basis for preservation decisions (§ 19.1.4.1.2.1; § 19.1.9.3.3.3).
Where the local Design Review Committee is not appointed the Planning Director will require the Historic Assessment Report and use it in discretionary decisions and CEQA compliance; the report essentially substitutes for committee recommendations (§ 19.1.4.1.2.4).
Because D is a combining zone, dimensional/development standards (setbacks, lot coverage, parking) generally come from the underlying zone and the County’s development standards; confirm cross‑references for parking and setbacks early (see Humboldt County Development Standards and Humboldt County Parking). (/us/california/humboldt-county/development-standards) (/us/california/humboldt-county/parking)

Links: design-review, development-standards, parking, overlay districts, nonconforming uses, variances, ADUs, California Building Standards Code are referenced inline above for easy cross-checking.

Checklist (what an applicant must satisfy, in roughly the order County staff will expect)

Confirm whether parcel lies in a D Zone, Samoa, Scotia, or is a County-designated historic structure (check County zoning maps). (§ 19.1.2; § 71.1.2)
If in D/Samoa/Scotia or altering a structure >45 years old, retain a qualified historic resources consultant (36 CFR Part 61 qualifications) and prepare a Historic Assessment Report that meets § requirements. (§ 19.1.4.1.2.2; § 55.4.12.1.14)
Submit Special Permit / design-review application with required fees if D-zone regulations apply. (§ 19.1.3.1–.2)
If demolition is proposed, include documentation and be prepared for potential demolition delay and conditions (documentation, relocation offers, possible limits on replacement scale). (§ 19.1.9.1.2; § 71.1.3)
Follow Secretary of the Interior’s Standards and the State Historic Building Code in reports and proposed design; include mitigation measures where avoidance is not feasible. (§ 19.1.4.1.2.3–.4)
Coordinate with County planning staff early to confirm whether local design-review committees are appointed or if the Director will act, and to confirm the exact list of materials required. (See procedural timelines in design-review chapters.) (§ 19.1.4.1.1.2)

Risks & Ambiguities

Issue	Why it matters	What to verify
Is a structure “contributing” or eligible?	A “contributing” label triggers stricter review, demolition limits, and requirement for Historic Assessment Reports (§ 19.1.9.1.3; § 55.4.12.1.14).	Verify with the Planning Department and request (or obtain) the County’s inventory or prior assessment.
Is a local design-review committee currently appointed?	If absent, the Director will require a Historic Assessment Report and act as reviewer; committee timing affects review timelines (§ 19.1.4.1.2; § 19.1.4.1.1.2).	Ask County staff whether the Samoa or Scotia DRC is active and their adopted review periods.
Overlap with State Housing Law	State law (e.g., Health & Safety Code) can require demolition in some cases, which changes County findings for denial (§ 19.1.9.1.1.2.4).	If demolition is proposed for housing, verify interactions with California housing laws and Housing Code. (/us/california/housing-laws)
Conflicts with building code upgrades	Historic standards may allow alternatives, but structural/life‑safety work is governed by the State Historic Building Code and Title 24; unclear scope can delay approvals (§ 19.1.4.1.2.1).	Coordinate early with Building Division on applicability of the State Historical Building Code (Title 24). (/us/california/building-codes)
Parcel/zone-specific exceptions (minimum parcel size)	Code allows exceptions for preservation but with conditions; unclear whether a given parcel qualifies (§ 71.1.4).	Verify on a parcel-by-parcel basis with planning staff — Verify with the jurisdiction.
Archaeological resources and ground disturbance	Ground disturbance may trigger excavation plans and stop-work protocols (this is separate from historic-structure review but often concurrent) (§ 16.2.5.6; § 55.4.12.1.15).	If grading/foundations are proposed, request a cultural-resources screening from the County and consult a qualified archaeologist.

Plain-English Summary

If your property in unincorporated Humboldt County is in a D design-control area, Samoa/Scotia townsite, or contains a building older than 45 years, expect extra paperwork: a design-review special permit, and likely a Historic Assessment Report prepared by a qualified consultant. The County uses the Secretary of the Interior’s Standards and the State Historical Building Code to judge changes; demolition is limited and can be delayed while alternatives are sought (§ 19.1; § 19.1.4; § 71.1; § 55.4.12.1.14).

Source References

Humboldt County Code, Design Review (D Zone), §§ 19.1.1–19.1.9 (Design Review, Samoa/Scotia provisions and SDRC authorities) — see § 19.1.1; § 19.1.2; § 19.1.3; § 19.1.4; § 19.1.9.
Humboldt County Code, County Historic Structures, § 71.1 (designation, prohibition on demolition/exterior alteration, exceptions to minimum parcel size). § 71.1.1–.4.
Historic Assessment Report requirements and contents, § 19.1.4.1.2 and related subsections (contents, professional qualifications per 36 CFR Part 61).
Samoa and Scotia additional standards for alterations and demolition, including demolition delay and replacement scale/facade requirements (§ 19.1.9.1.2; § 19.1.9.1.3; § 19.1.9.3.3).
Project threshold for historic reports (structures > 45 years) and related consultant/report requirements, § 55.4.12.1.14.
Archaeological excavation plan requirements for ground-disturbing projects, § 16.2.5.6.

Related internal reference pages (useful cross-checks):

Humboldt County Design Review (/us/california/humboldt-county/design-review) — linked above where design review is discussed.
Humboldt County Development Standards (/us/california/humboldt-county/development-standards) — for setbacks/dimensional rules.
Humboldt County Parking (/us/california/humboldt-county/parking) — for project parking compliance.
Humboldt County Overlay Districts (/us/california/humboldt-county/overlay-districts) — to confirm D and other overlays.
Humboldt County Nonconforming Uses (/us/california/humboldt-county/nonconforming-uses) — referenced when adaptive reuse/nonconforming use issues arise.
Humboldt County Variances and Exceptions (/us/california/humboldt-county/variances-and-exceptions) — for parcel-size or dimensional exceptions.
California ADU law (/us/california/california-adu-laws) and California housing laws (/us/california/housing-laws) — verify state housing-law interactions if demolition affects housing.
California Building Standards Code (Title 24) (/us/california/building-codes) — for building-code alternates under the State Historical Building Code.

Sources

Retrieved passages

California Building Code High relevance
CBC § 2466 (chapter including) High relevance
Humboldt County Zoning Code (Section CZ) High relevance
California Building Code (chapter including) High relevance
Humboldt County Zoning Code High relevance
CBC § 1913 (section is) High relevance
Humboldt County Zoning Code (Section 69.1.5) High relevance
Humboldt County Zoning Code (Section CZ) High relevance

Cited sections

Humboldt County Code, Design Review (D Zone), §§ 19.1.1–19.1.9 (Design Review, Samoa/Scotia provisions and SDRC authorities) — see § 19.1.1; § 19.1.2; § 19.1.3; § 19.1.4; § 19.1.9. (§ 19.1.1)
Humboldt County Code, County Historic Structures, § 71.1 (designation, prohibition on demolition/exterior alteration, exceptions to minimum parcel size). § 71.1.1–.4. (§ 71.1)
Historic Assessment Report requirements and contents, § 19.1.4.1.2 and related subsections (contents, professional qualifications per 36 CFR Part 61). (§ 19.1.4.1.2)
Samoa and Scotia additional standards for alterations and demolition, including demolition delay and replacement scale/facade requirements (§ 19.1.9.1.2; § 19.1.9.1.3; § 19.1.9.3.3). (§ 19.1.9.1.2)
Project threshold for historic reports (structures > **45 years**) and related consultant/report requirements, § 55.4.12.1.14. (§ 55.4.12.1.14.)
Archaeological excavation plan requirements for ground-disturbing projects, § 16.2.5.6. (§ 16.2.5.6.)
Humboldt County Design Review (/us/california/humboldt-county/design-review) — linked above where design review is discussed.
Humboldt County Development Standards (/us/california/humboldt-county/development-standards) — for setbacks/dimensional rules.
Humboldt County Parking (/us/california/humboldt-county/parking) — for project parking compliance.
Humboldt County Overlay Districts (/us/california/humboldt-county/overlay-districts) — to confirm D and other overlays.
Humboldt County Nonconforming Uses (/us/california/humboldt-county/nonconforming-uses) — referenced when adaptive reuse/nonconforming use issues arise.
Humboldt County Variances and Exceptions (/us/california/humboldt-county/variances-and-exceptions) — for parcel-size or dimensional exceptions.
California ADU law (/us/california/california-adu-laws) and California housing laws (/us/california/housing-laws) — verify state housing-law interactions if demolition affects housing.
California Building Standards Code (Title 24) (/us/california/building-codes) — for building-code alternates under the State Historical Building Code. (Title 24)
HumboldtCounty_ZoningCode.md

Frequently asked questions

Do I need design review for work on a historic house in unincorporated Humboldt County?

If your property lies in a D Zone or in a special plan area (for example Samoa or Scotia) then yes — design review (and a Special Permit for D-zone work) will be required (§ 19.1.2–.3; § 19.1.9). If a local Design Review Committee is not appointed, the Planning Director will require a Historic Assessment Report and act in place of the committee (§ 19.1.4.1.2).

What triggers a Historic Assessment Report?

A Historic Assessment Report is required where the local design-review committee is absent for Samoa/Scotia review areas and for projects that remove or alter structures older than 45 years; the report must be prepared by a consultant meeting Secretary of the Interior professional qualifications and include specified inventories, maps, and recommendations (§ 19.1.4.1.2.1–.2.2; § 55.4.12.1.14).

Can the County block demolition of a County-designated historic structure?

Yes. Once a structure is designated a County historical structure, exterior alteration or demolition is restricted; the Board can delay demolition, require documentation, and pursue alternatives (acquisition, relocation) during the delay period (§ 71.1.3.1–.3). Normal maintenance is allowed without prior design-review approval (§ 71.1.3.1).

What standards will the County use to judge alterations or rehabilitation?

The County explicitly applies the Secretary of the Interior’s Standards and Guidelines and the Department of Interior’s Standards of Rehabilitation, together with the State Historical Building Code and local Samoa/Scotia Design Guidelines where applicable (§ 19.1.4.1.2.1; § 19.1.9.3.3.3).

If the County’s Design Review Committee is not active, who reviews my project?

If a local committee (e.g., SDRC or Scotia DRC) is not appointed, the Planning Director becomes the reviewing authority and will require a Historic Assessment Report; the recommendations in that report substitute for committee recommendations and are used for permit and CEQA decisions (§ 19.1.4.1.2.4; § 19.1.9.3.2.1–.2).

What about archaeological resources during construction?

Ground-disturbing work may trigger archaeological mitigation, including a plan of excavation prepared by a qualified archaeologist; the County requires planning and can limit ground disturbance or require excavation, recording, and reporting (§ 16.2.5.6).

Are there any fast thresholds (years/ages) I should be aware of?

Yes. The County’s cannabis-permit chapter and other project review rules flag structures over 45 years old as potentially historic and require consultant evaluation when those structures are removed or altered (§ 55.4.12.1.14).

Can the County relax parcel-size minimums to preserve a historic building on an agricultural parcel?

Yes — the code allows exceptions to minimum parcel size for County-designated historic structures or State/Federal-listed buildings, provided conditions are met (e.g., no adverse impact on agricultural viability) (§ 71.1.4). Verify parcel eligibility with staff.

If I want to add an ADU to an older primary house, does historic preservation law stop me?

Not automatically. ADUs must comply with State ADU law, but if the property is in a D Zone, Samoa/Scotia, or the structure is contributing/older than 45 years, design-review standards and a historic assessment may be required to evaluate exterior work and impacts — coordinate both the historic review and ADU procedural requirements early. Verify overlaps with ADU and design-review staff. (/us/california/california-adu-laws)

Ask about any Humboldt County property

Get a cited, plain-English answer on Humboldt County zoning, setbacks, FAR, ADUs and permits — for any address.

Start Free Trial