Local zoning · Santa Clara County

Santa Clara County — Historic Preservation

Q: Do I need a Landmark Alteration Permit to change windows on a historic house in the unincorporated areas?

Yes, exterior alterations to a designated landmark need a Landmark Alteration Permit, but like-for-like replacement that matches existing or original windows can qualify for Small Project Review, which is faster (§ C17-13; § C17-17).

Q: My building is in the Heritage Resource Inventory but not designated. Can the County stop my demolition?

Yes. If the County finds the inventoried building meets landmark criteria, you must obtain a Landmark Alteration Permit before demolition; review follows the same procedures as for landmarks (§ C17-23).

Q: What does the HHC actually do on my application?

The HHC holds a public hearing, takes testimony, and recommends approval, conditional approval, or denial. The Director then issues the decision within set timeframes (appeals per § C17-19) (§ C17-15).

Q: Are there special height or setback rules in the New Almaden “-h 1” district?

Yes. Height is limited to 35 feet and two stories, and the Zoning Administrator may adjust front setbacks on certain Almaden Road properties to maintain historic building placement (§ 3.50.090.C).

Q: Can I build an ADU on a property in the “-h 1” district?

ADUs are allowed by right in “-h 1,” subject to the County’s ADU standards in § 4.10.015, and you must still comply with any applicable preservation approvals (§ 3.50.090.B.1.e; § C17-13).

Q: Does the “-h” overlay override my base zoning?

Where the “-h” ordinance adopts special use or development standards, those supersede conflicting base-district rules; if no “-h” standards are adopted, base zoning applies (§ 3.50.050.B; § 3.50.060.B).

Q: Who decides on demolition of a registered cultural heritage resource?

The Board of Supervisors must approve demolition or removal; County demolition procedures in County Code C1-91 also apply (§ 3.50.070.A–B).

Q: Can I get zoning flexibility (like parking or setback relief) for preservation work?

Possibly. The County’s incentives allow Zoning Ordinance modifications for designated landmarks, including flexibility in parking , uses, setbacks, and landscape requirements (§ C17-24).

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

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Last reviewed: July 6, 2026

Overview

In unincorporated areas of Santa Clara County, historic preservation is governed by the County’s Historic Preservation Ordinance (Division C17) and the “-h” Historic Preservation Combining Districts in the County Zoning Ordinance (Chapter 3.50). Together, they create a system for landmark designation, permit review, and overlay-based standards that can supersede base zoning where needed to protect historic resources. The County’s Historical Heritage Commission (HHC) advises on designations and reviews major proposals affecting designated resources and “-h” overlay areas. See the Santa Clara County zoning & planning overview for context.

If your property is a designated landmark, or lies in a “-h” Historic Preservation Combining District and is listed in the heritage resource inventory, any exterior alteration or demolition generally requires a landmark alteration permit before work can proceed (§ C17-13; process in §§ C17-14–C17-17).

How the County’s preservation framework works (unincorporated areas)

The County maintains a Heritage Resource Inventory used to identify resources and inform future designations (§ C17-4).
A property can be designated a Landmark if it meets age, integrity, and significance criteria (§ C17-5). Designation can be initiated by the owner, HHC, or Board (§ C17-6), noticed (§ C17-8), heard by HHC (§ C17-9), and then acted on by the Board; adopted designations are noticed and recorded (§ C17-11).
The County can adopt “-h” Historic Preservation Combining Districts to protect areas with at least one registered cultural resource; “-h” standards can supersede base zoning where adopted (§§ 3.50.010, 3.50.020, 3.50.060.B).
For projects in “-h” areas, applications for design review or ASA must be referred to the HHC (§ 3.50.040).

What triggers County review and permits

A Landmark Alteration Permit is required for:
- Any alteration or demolition of a designated landmark (§ C17-13).
- Demolition of an undesignated resource that is in the Heritage Resource Inventory and found to meet landmark criteria (§ C17-23).
The County can use a faster Small Project Review for defined, low-impact scopes (e.g., replacement-in-kind windows; additions <200 sq ft to side/rear) (§ C17-17).
The decision-maker must make specific permit findings (e.g., compliance with Secretary of the Interior’s Standards; no significant adverse effect, or no feasible alternative) (§ C17-16).
If denial would deprive all reasonable use, owners may seek a hardship determination (§ C17-18).
For “registered cultural heritage resources,” demolition or removal requires Board approval (§ 3.50.070.A), with demolition procedures cross-referenced to County Code C1-91 (§ 3.50.070.B).

The “-h” Historic Preservation Combining Districts (overlay)

The “-h” overlay provides a framework to tailor protections by area. Upon adoption, the Board may set special development standards (height, massing, materials, setbacks, parking, and signs) that supersede conflicting base-district rules (§§ 3.50.060.A–B; 3.50.050.B).

Before any discretionary approval in a “-h” area, the approving authority must find the use consistent with the overlay’s intent and any adopted plans/standards (§ 3.50.050.A).
The Planning Commission may require removal/cessation of incompatible outdoor uses or advertising signs after hearing (§ 3.50.050.C).
Establishing a “-h” district requires a report with boundaries, resource descriptions, and recommended standards (§ 3.50.080.B).

-h Historic Preservation Combining Districts (All -h overlays)

Purpose: Preserve historic sites/structures and other heritage resources; can apply to areas with special character/architectural value if they contain at least one registered resource (§ 3.50.010).
Where it applies: Any unincorporated area designated by ordinance as a “-h” district; general provisions apply to all “-h” districts (§ 3.50.020).
Typical permitted uses and standards: Follow base zoning unless the “-h” district ordinance adopts special use or development standards that supersede base rules (§§ 3.50.050.B, 3.50.060.B).
Key process notes:
- Design review/ASA referrals go to HHC before hearing (§ 3.50.040).
- Demolition/removal of registered resources requires Board approval (§ 3.50.070.A).

-h 1 (New Almaden National Historic Landmark District)

Purpose: Preserve the New Almaden National Historic Landmark District; boundaries follow the federally listed district. Most land is within Almaden Quicksilver County Park, plus privately owned, primarily residential parcels (§ 3.50.090.A).
Uses permitted by right (§ 3.50.090.B.1):
- Single-family residences with residential accessory uses/structures.
- Agriculture (as allowed by the base district).
- Community Care – Limited.
- Home Occupations (§ 4.10.180).
- Accessory Dwelling Units (ADUs) per § 4.10.015.
Uses requiring discretionary approvals (§ 3.50.090.B.2–4):
- Special Permit: Home Occupation – Expanded; accessory structures with >2 internal plumbing fixtures; and Historic Structure – Use Conversion with findings (consistency with district intent/character; compliance with § 4.10.170 and any applicable supplemental use regs).
- Architecture & Site Approval (ASA): Minor utilities.
- Use Permit + ASA: Nonprofit institutions serving the New Almaden community; major utilities.
Key dimensional/character standards (§ 3.50.090.C–D):
- Height: Max 35 ft and no more than two stories; accessory structure rules of § 4.20.020(E) apply.
- Setback flexibility for preservation: Along Almaden Road Priority List 1 properties, historic building placements should be maintained; front setbacks may be adjusted without a variance if the Zoning Administrator finds it furthers preservation and remains consistent with district integrity (§ 3.50.090.C.1–2).
- The ordinance includes prioritized lists of historic structures (e.g., Casa Grande, Carson-Perham Adobe) to guide preservation emphasis (§ 3.50.090.D).

Landmark designation, permits, and incentives

Designation criteria: 50+ years (with exceptions), retains integrity, and meets one or more significance criteria (events, persons, design/work of a master/artistic value, or information potential) (§ C17-5).
Pending designation hold: Once an owner application is accepted or HHC/Board initiates designation, no alteration/demolition permits are issued until a landmark alteration permit is granted (§ C17-7).
Landmark Alteration Permit process: Application (§ C17-14); HHC recommendation and Director decision within specified timeframes; appeals per § C17-19; denial should not deprive all reasonable use (§ C17-15.C) (§§ C17-14–C17-15).
Required findings: Compliance with Secretary of the Interior’s Standards; compatibility of any detached new construction; feasibility analysis for alternatives; potential 6‑month demolition wait (§ C17-16).
Small Project Review: Eligible low-impact scopes may be approved administratively; otherwise proceed to full HHC review (§ C17-17).
Hardship: Board may approve alteration/demolition upon finding denial would deprive all reasonable use/return (§ C17-18).
Revocation: Noncompliance or fraud can revoke a permit (§ C17-21).
Incentives: Board may adopt zoning modifications (e.g., flexible parking, uses, setbacks, landscaping, potential transfer of development rights), fee reductions/waivers, expedited processing, recognition programs (§ C17-24). Owners in “-h” districts may pursue Mills Act property tax contracts (§ C17-25).
State codes: The County implements the State Historical Building Code (SHBC) for qualified historical buildings (§ C17-26). For building standards generally, see the California Building Standards Code.

Decision-critical standards and reviews (unincorporated areas)

Topic	Where it applies	What it does	Who decides	Code Reference
Landmark Alteration Permit	Designated landmarks; demolition of certain inventoried resources	Required before exterior alteration/demolition	HHC recommends; Director decides; Board for County-owned	§ C17-13–C17-15
Permit Findings	All Landmark Alteration Permits	Secretary’s Standards; no significant adverse effect; feasibility alternatives	Director/Board	§ C17-16
Small Project Review	Minor/like-for-like scopes	Streamlined approval without hearing	Director	§ C17-17
Demolition of registered resource	Any registered cultural heritage resource	Requires Board approval before demolition/remove	Board of Supervisors	§ 3.50.070.A–B
“-h” overlay supersedes base rules	Any adopted “-h” district	Special “-h” use/dev standards override conflicts	As specified by ordinance	§ 3.50.050.B; § 3.50.060.B
HHC referral for design review/ASA	All “-h” districts	HHC review & recommendation prior to public hearing	HHC advisory	§ 3.50.040
-h 1: Allowed by right	New Almaden	SFR, accessory uses, limited ag, community care-limited, home occupations, ADUs	By right	§ 3.50.090.B.1; § 4.10.015; § 4.10.180
-h 1: Height limit	New Almaden	Max 35 ft; ≤2 stories	N/A	§ 3.50.090.C.3
-h 1: Setback flexibility	New Almaden (Priority List 1 along Almaden Rd)	ZA may adjust front setbacks to match historic placement	Zoning Administrator	§ 3.50.090.C.1–2

Tip: If you’re planning an ADU on a landmark or in “-h 1,” the ADU must still meet County ADU rules; see California ADU law and County Land Use basics. ADUs are listed as a by-right use in “-h 1” subject to § 4.10.015 (§ 3.50.090.B.1.e).

Checklist

Confirm whether the parcel is a designated Landmark or lies within a “-h” overlay in unincorporated areas; request the Heritage Resource Inventory entry (§ C17-4).
If designated or inventoried, scope your project to see if a Landmark Alteration Permit is required (§ C17-13).
If eligible, consider Small Project Review to streamline minor work (§ C17-17).
Prepare plans consistent with the Secretary of the Interior’s Standards to support required findings (§ C17-16).
If in a “-h” district, confirm any special use/height/setback/sign standards that supersede base zoning (§ 3.50.060.A–B).
File the application; the HHC will review and recommend; Director issues the decision (§ C17-15; § 3.50.040 for design review referrals).
If demolition is involved in a registered resource, plan for Board approval and additional procedures (§ 3.50.070).
Explore incentives (zoning flexibility, Mills Act) to offset preservation costs (§§ C17-24–C17-25).

Risks & Ambiguities

Issue	Why it matters	What to verify
Pending designation “hold”	Applications can be paused until a Landmark Alteration Permit is processed (§ C17-7).	Ask County staff if any owner-initiated or HHC/Board-initiated designation is pending on your parcel.
Base zoning vs “-h” standards	“-h” standards can override base rules (§ 3.50.060.B).	Confirm which “-h” standards were adopted for your overlay; if none, base zoning applies.
What counts as “small project”	Determines if you can be approved administratively (§ C17-17).	Match your scope to listed eligibility (e.g., replacement-in-kind windows, <200 sf side/rear additions).
Demolition thresholds	Registered resources require Board approval; inventoried resources may trigger a Landmark Alteration Permit (§§ 3.50.070; C17-23).	Whether your building is “registered” or simply inventoried; ask staff to confirm status.
HHC referral for design review	HHC must review applications in “-h” areas before hearing (§ 3.50.040).	Build time into your schedule for HHC review and any recommendations/conditions.
Stanford GUP exception	Stanford properties follow GUP terms except where C17 adds extra protections (§ C17-22).	If on Stanford land, confirm which C17 provisions still apply.
Nonconforming/outdoor uses in “-h”	Some incompatible outdoor uses/signs can be ordered removed (§ 3.50.050.C).	If you have legacy outdoor uses/signage, confirm whether they conflict with “-h” policies.

Plain-English Summary

If you own a historic property in the unincorporated areas, expect two layers: countywide rules for landmark properties and, in some areas, a “-h” overlay with custom standards. Many exterior changes and any demolition need a Landmark Alteration Permit, reviewed by the HHC with strict findings focused on preservation; small, like-for-like work may be streamlined. The “-h 1” New Almaden district allows typical residential uses and ADUs, but caps height at 35 feet and can adjust setbacks to maintain historic placement.

Source References

Historic Preservation Ordinance (Division C17): §§ C17-1–C17-4 (purpose, definitions, inventory); § C17-5 (designation criteria); §§ C17-6–C17-12 (process, notices, repeal); §§ C17-13–C17-21 (permits, findings, small projects, hardship, revocation); § C17-22 (Stanford GUP); § C17-23 (demolition of inventoried resources); §§ C17-24–C17-26 (incentives, Mills Act, SHBC).
Zoning Ordinance “-h” Historic Preservation Combining Districts (Chapter 3.50): §§ 3.50.010–3.50.020 (purpose, applicability); § 3.50.040 (HHC referral); § 3.50.050 (special use regs/findings); § 3.50.060 (special development standards); § 3.50.070 (demolition/removal); § 3.50.080 (adoption procedures); § 3.50.090 (“-h 1” New Almaden: purpose, uses, standards).

Also see related topics:

Sources

Retrieved passages

CBC § C3 (Article III.) High relevance
Santa Clara County Zoning Code (§ 3.50.090.) High relevance
Santa Clara County Zoning Code (Title of) High relevance
Santa Clara County Zoning Code (§ 3) High relevance
Santa Clara County Zoning Code (Chapter 3.50) High relevance
CBC § 1 (§ 1) High relevance
Santa Clara County Zoning Code (§ 1) High relevance
Santa Clara County Zoning Code (article sets) High relevance
Santa Clara County Zoning Code (Article II) High relevance
Santa Clara County Zoning Code (§ 6) High relevance

Cited sections

Official Santa Clara County code library

Frequently asked questions

Do I need a Landmark Alteration Permit to change windows on a historic house in the unincorporated areas?

Yes, exterior alterations to a designated landmark need a Landmark Alteration Permit, but like-for-like replacement that matches existing or original windows can qualify for Small Project Review, which is faster (§ C17-13; § C17-17).

My building is in the Heritage Resource Inventory but not designated. Can the County stop my demolition?

Yes. If the County finds the inventoried building meets landmark criteria, you must obtain a Landmark Alteration Permit before demolition; review follows the same procedures as for landmarks (§ C17-23).

What does the HHC actually do on my application?

The HHC holds a public hearing, takes testimony, and recommends approval, conditional approval, or denial. The Director then issues the decision within set timeframes (appeals per § C17-19) (§ C17-15).

Are there special height or setback rules in the New Almaden “-h 1” district?

Yes. Height is limited to 35 feet and two stories, and the Zoning Administrator may adjust front setbacks on certain Almaden Road properties to maintain historic building placement (§ 3.50.090.C).

Can I build an ADU on a property in the “-h 1” district?

ADUs are allowed by right in “-h 1,” subject to the County’s ADU standards in § 4.10.015, and you must still comply with any applicable preservation approvals (§ 3.50.090.B.1.e; § C17-13).

Does the “-h” overlay override my base zoning?

Where the “-h” ordinance adopts special use or development standards, those supersede conflicting base-district rules; if no “-h” standards are adopted, base zoning applies (§ 3.50.050.B; § 3.50.060.B).

Who decides on demolition of a registered cultural heritage resource?