Local zoning · Los Altos
Los Altos — Historic Preservation
Historic Preservation under the Los Altos local zoning and planning code, with the controlling citations.
Last reviewed: July 2, 2026
Overview
This page explains how the City of Los Altos regulates historic resources under the local zoning/planning ordinance (Title 14). It focuses only on the local historic-preservation chapters: the Historic Preservation chapter (Chapter 14.93) and the Mills Act program (Chapter 14.95), how the city's Historic Resources Inventory (HRI) functions, and where historic rules intersect with zoning (especially the CD / CD/R3 downtown districts and ADU rules). For citywide planning context see the Los Altos zoning & planning overview.
What the code requires (core rules and how they are applied)
- Mandatory designation criteria: a property must be over 50 years old and retain integrity to be listed as a historic resource or historic landmark on the city's HRI; the designation procedure and criteria are codified in § 14.93.040 .
- Historic Alteration Permits are required to alter, demolish, remove, relocate or change exterior architectural features of an HRI property; this permit requirement is § 14.93.050 .
- Review authority: the Historical Commission reviews designation applications and historical alteration permit requests and issues recommendations; the zoning administrator or other review body takes final action as set out in § 14.93.060 and related procedures § 14.93.070–.080 .
- Secretary of the Interior Standards: projects affecting designated resources must comply with the Secretary of the Interior's Standards for the Treatment of Historic Properties; this compliance requirement is stated in § 14.93.060.A.3 and repeated in the Mills Act eligibility and contract provisions § 14.95.080 .
- Ordinary maintenance is exempt: routine painting, maintenance and landscaping that do not change design or materials are exempt from historic-alteration-permit requirements pursuant to § 14.93.110 .
- Duty to maintain: owners must keep historic resources in good repair; enforcement and misdemeanor penalties are in § 14.93.120 and § 14.93.130 .
- Mills Act contracts: Los Altos offers the Mills Act historic-contract program (Chapter 14.95) for qualified historic properties; eligibility, required contract provisions, application timing, review and recordation procedures are in § 14.95.020–.100 (see application detail in § 14.95.060 and review timing in § 14.95.090) .
Because preservation outcomes intersect with zoning details (setbacks, lot coverage, parking), consult the city's Los Altos Zoning and Los Altos Development Standards pages when preparing applications. If your project affects vehicle access or parking requirements, consult the Los Altos Parking page. Historic-related design consistency requirements may trigger the city's Los Altos Design Review. For historic overlays and district mapping see Los Altos Overlay Districts. For proposals that add dwelling units, note the ADU rules at Los Altos ADUs and the state building rules at California Building Standards Code.
District-by-district breakdown (where the ordinance mentions historic preservation)
CD/R3 (Downtown Commercial/Residential)
- Purpose: Encourage a downtown village atmosphere and specifically to encourage historic preservation for buildings listed on the city's HRI as part of downtown character objectives (§ 14.52.020.G) .
- Typical permitted uses: retail, restaurants (no drive-through), offices, mixed-use and some residential uses are explicitly allowed in § 14.52.030 (business, mixed-use, parking, restaurants, retail, etc.) .
- Key dimensional standards: The downtown chapters reference Chapter 14.66 (general provisions) for many development standards; specific numeric setbacks, heights and lot coverage are set elsewhere in the code. Where historic buildings are involved the downtown purpose explicitly encourages preservation but does not substitute the Historic Preservation chapter's permit controls (§ 14.52.020.G) .
- Where it applies: Downtown village core and immediate surroundings (see Chapter 14.52 / zone map); historic preservation objectives are built into downtown review processes .
CD (Commercial Downtown)
- Purpose: The CD district lists preservation and the downtown character among its purposes; specifically to encourage historic preservation for buildings on the city's HRI and to retain village atmosphere (§ 14.44.020.G) .
- Typical permitted uses: general downtown retail, office and service uses (purposes and permitted uses are in the CD chapter); historic resources in this district are subject to the same Historic Preservation chapter rules when designated § 14.93.x apply .
- Dimensional standards: Numeric standards remain in the development-standards chapters and downtown design sections; the Historic Preservation chapter overlays the required historic-permit/review rules but does not replace numeric requirements (see Los Altos Development Standards).
Citywide: Historic Resources Inventory (HRI) properties (designation ‘overlay’)
- Purpose: The HRI is the city's official list of historic resources and landmarks; listing subjects a property to historic-permit review and protection measures in Chapter 14.93. The HRI is adopted/amended by resolution of City Council and defined in § 14.93.020 .
- Effect on uses/standards: A property listed on the HRI or designated as a historic landmark must obtain a historic alteration permit for exterior alterations, demolition or relocation of character-defining elements (§ 14.93.050) and follow the Secretary of the Interior's Standards during review (§ 14.93.060.A.3) . Ordinary maintenance is exempt (§ 14.93.110) .
- Where it applies: Citywide — any parcel the city designates and records on the HRI; designation procedure and notice requirements are in § 14.93.040 .
Architecturally and Historically Significant Historic District (ADU-specific reference)
- Context: The ADU chapter notes that a parcel "within an architecturally and historically significant historic district" is entitled to a parking exemption for accessory dwellings (§ 14.14.100.4) and that ADUs on historic properties require ministerial design-review compliance with Chapter 12.44 and Secretary of the Interior's Standards (ADU chapter, Historic Properties clause) .
- Practical implication: If your lot sits inside a named historic district or the city’s HRI, ADU-related parking and review rules differ; verify district status early with Development Services and consult Los Altos ADUs.
Most decision-relevant standards / permitted-use snapshot
| Item | What it controls (plain-English) | Code reference |
|---|---|---|
| HRI designation criteria | Age > 50 years, integrity and significance tests (event, person, architecture, archaeology) | § 14.93.040 |
| Historic alteration permit required | Required to alter/demolish/relocate/change exterior features on HRI properties | § 14.93.050 |
| Application contents for historic permit | Site plan, boundary survey, elevations, photos, materials, notes on deviations from Secretary standards | § 14.93.070 |
| Review standard | Historical Commission recommends; decision must show compliance with Secretary standards | § 14.93.060 |
| Ordinary maintenance exemption | Routine painting/maintenance/landscaping exempt from historic permit | § 14.93.110 |
| Owner maintenance duty/enforcement | Owner must maintain historic resource; violations can be misdemeanors | § 14.93.120–.130 |
| Mills Act program basics | Eligibility and contract requirements, 10-year minimum contract, annual automatic extension, recordation timing | § 14.95.030, § 14.95.050–.100 |
| ADU treatment on historic properties | ADU on historic property is ministerial but must comply with design criteria and Secretary standards; parking exemptions for historic district parcels | ADU chapter (e.g., § 14.14.100, ADU historic clause) |
Checklist (what an applicant must satisfy for work on a Los Altos historic property)
- Confirm whether the property is listed on the city's Historic Resources Inventory (HRI) or otherwise qualifies as a historic resource (§ 14.93.020, § 14.93.040) .
- If not listed but believed eligible, prepare a DPR 523A (historic resource survey) by a qualified professional per § 14.93.030 .
- For most exterior changes, submit a Historic Alteration Permit application with site plan, elevations, photographs, materials list and notes on any deviations from the Secretary of the Interior's Standards (§ 14.93.070) .
- Pay required fees and provide any consultant deposits (Mills Act and designation applications require fees set by Council) (§ 14.95.070) .
- Coordinate early with the Historical Commission and Development Services staff (joint meetings are possible when multiple discretionary approvals are needed — § 14.93.080) .
- Where building-code compliance is needed, evaluate alternatives under the California Historical Building Code (CHBC) before removing historic features (§ 14.93.050.D) .
- If pursuing a Mills Act contract, submit application by the city deadline (applications accepted before July 1 for processing that calendar year) and be prepared to record the contract by Dec 31 when needed for tax reassessment (§ 14.95.040.C, § 14.95.090) .
- If proposing an ADU on a historic property or inside a historic district, follow the ministerial ADU review rules in the ADU chapter and comply with design criteria and Secretary standards (ADU chapter: § 14.14.100 and related ADU provisions) .
Risks & Ambiguities
| Issue | Why it matters | What to verify |
|---|---|---|
| Owner consent not required for designation | City may proceed with HRI listing even if owner objects, though owner is notified and can comment (owner consent not required) | Confirm current notice practice and timeline with Development Services; see § 14.93.040 |
| Applicability of Secretary standards to minor changes | Code requires compliance for projects that require historic alteration permits, but exemptions exist for non-permanent items and ordinary maintenance | Verify whether proposed work is exempt under § 14.93.050.B–C and § 14.93.110; when in doubt submit a permit application or pre-application meeting request |
| Numeric development standards (setbacks/height) for historic lots | The Historic Preservation chapter imposes review and preservation duties but does not change numeric zoning standards (setbacks/height/coverage) | Check the applicable base zone chapter and Los Altos Development Standards to confirm dimension rules; the Historic chapter does not list numeric standards (Not found in retrieved materials) |
| ADU design & parking on historic parcels | ADU ministerial pathway exists but requires compliance with design criteria and may trigger special parking exemptions | Confirm whether your lot lies in a formally recognized historic district and whether the ADU qualifies for the parking exemption under § 14.14.100.4 and historic-property ADU clause |
| Mills Act financial/tax effect timing | Mills Act applications must meet calendar deadlines to affect the next fiscal year's assessment | Verify time-sensitive dates and required documentation with Development Services and the County Assessor; see § 14.95.040.C and § 14.95.060 |
Plain-English Summary
If your Los Altos property is listed on the city's Historic Resources Inventory (HRI) or is designated as a historic landmark, Chapter 14.93 requires you to apply for a Historic Alteration Permit before changing or removing exterior historic features and directs reviewers to use the Secretary of the Interior's Standards; routine maintenance is exempt and owners must keep historic buildings in good repair. The city also runs a local Mills Act contract program for qualifying properties that provides tax incentives in exchange for a recorded preservation contract; rules and application timing are in Chapter 14.95. See the city's zoning maps and downtown rules for how preservation objectives interact with district-specific standards .
Source References
- Los Altos Municipal Code, Chapter 14.93 — Historic Preservation (purpose, definitions, designation, historic alteration permits, review, exemptions, maintenance, enforcement) — see § 14.93.010–.130 .
- Los Altos Municipal Code, Chapter 14.95 — Mills Act Program (authority, eligibility, contract provisions, application, review, recordation, cancellation) — § 14.95.010–.150 .
- Downtown zoning purposes and historic-preservation objective: CD and CD/R3 district purpose statements (§ 14.44.020, § 14.52.020) .
- Historic Alteration Permit application details and review: § 14.93.050–.070 .
- ADU treatment for historic properties and parking exceptions: ADU chapter (e.g., § 14.14.100 and ADU historic clauses) .
- Secretary of the Interior's Standards referenced throughout Chapter 14.93 and 14.95 (see the code citations above) .
- For ministerial development standards, design-review processes, and overlay mapping consult the city pages: Los Altos Zoning, Los Altos Development Standards, Los Altos Design Review, Los Altos Overlay Districts, and Los Altos Parking.
- State/building-code context referenced in the ordinance: California Building Standards Code and California ADU guidance (uploaded handbook excerpt) .
Sources
Retrieved passages
- CBC § 1 (§ 1) High relevance
- CBC § 1 (§ 1) High relevance
- CBC § 1 (§ 1) High relevance
- Los Altos Zoning Code (§ 1) High relevance
- Los Altos Zoning Code (chapter no) High relevance
- Los Altos Zoning Code (chapter no) Medium relevance
- Los Altos Zoning Code (Chapter 14.66) Medium relevance
- Los Altos Zoning Code (§ 1) Medium relevance
- CBC § 1 (§ 1) High relevance
- CBC § 1 (chapter is) High relevance
Cited sections
- Los Altos Municipal Code, Chapter **14.93 — Historic Preservation** (purpose, definitions, designation, historic alteration permits, review, exemptions, maintenance, enforcement) — see **§ 14.93.010–.130** . (§ 14.93.010)
- Los Altos Municipal Code, Chapter **14.95 — Mills Act Program** (authority, eligibility, contract provisions, application, review, recordation, cancellation) — **§ 14.95.010–.150** . (§ 14.95.010)
- Downtown zoning purposes and historic-preservation objective: **CD** and **CD/R3** district purpose statements (**§ 14.44.020**, **§ 14.52.020**) . (§ 14.44.020)
- Historic Alteration Permit application details and review: **§ 14.93.050–.070** . (§ 14.93.050)
- ADU treatment for historic properties and parking exceptions: ADU chapter (e.g., **§ 14.14.100** and ADU historic clauses) . (§ 14.14.100)
- Secretary of the Interior's Standards referenced throughout Chapter **14.93** and **14.95** (see the code citations above) .
- For ministerial development standards, design-review processes, and overlay mapping consult the city pages: Los Altos Zoning, Los Altos Development Standards, Los Altos Design Review, Los Altos Overlay Districts, and Los Altos Parking.
- State/building-code context referenced in the ordinance: California Building Standards Code and California ADU guidance (uploaded handbook excerpt) .
- LosAltos_ZoningCode.md
- 2025 California ADU handbook.md
Frequently asked questions
How does Los Altos define a "historic resource" for zoning purposes?
A historic resource in Los Altos is a property determined to be over 50 years old (or eligible under CEQA criteria) that retains sufficient integrity and has historical, architectural, cultural or aesthetic value; definitions and HRI rules are in § 14.93.020 and designation criteria in § 14.93.040 .
Do I need a permit to change the exterior of a house on the HRI?
Yes — most exterior alterations, demolitions, relocations or changes to character-defining features of an HRI property require a Historic Alteration Permit; see § 14.93.050 for the requirement and § 14.93.070 for application contents .
Who reviews historic-permit applications in Los Altos?
The Historical Commission reviews and issues recommendations; the recommendation is forwarded to the zoning administrator (or other applicable decision-maker) for final action. The review standard requires compliance with the Secretary of the Interior's Standards (§ 14.93.060) .
Can I do routine repairs without a historic permit?
Yes — ordinary maintenance, painting, landscaping and repairs that do not change design, materials or appearance are exempt from the historic-alteration-permit requirement per § 14.93.110 .
What are Mills Act contracts and can I apply?
Los Altos implements the Mills Act local-contract program in Chapter 14.95. Only qualified historical properties (e.g., listed on the HRI, State or National Register) are eligible; contracts require a 10‑year minimum term, specific maintenance/rehab programs and recordation. See § 14.95.030–.060 for definitions and application requirements and § 14.95.090 for application timing and review .
If my property is under historic review can I get a building permit?
Generally no — if designation is pending, the code bars major-alteration, demolition or building permits that would affect the property until hearings conclude (§ 14.93.040.C) . For safety issues the California Historical Building Code (CHBC) should be evaluated before removal of historic features (§ 14.93.050.D) .
Are ADUs allowed on historic properties in Los Altos?
Yes. ADUs are allowed but ADUs on historic properties must meet the design-review criteria and be consistent with the Secretary of the Interior's Standards; ADU parking exemptions may apply if the parcel is within an architecturally and historically significant historic district (ADU chapter, e.g., § 14.14.100) .
What does Los Altos expect in a Historic Alteration Permit application?
At minimum: a clear work statement, site plan and boundary survey, detailed existing and proposed exterior elevations, photographs of character features, materials/specifications, and notes on any deviations from Secretary standards as listed in § 14.93.070 .
If my Mills Act contract is cancelled, what happens?
If the city cancels a recorded historic-contract the owner may owe a cancellation fee equal to 12.5% of current fair market value as determined by the assessor; cancellation procedures and findings are in § 14.95.140 .
What design standard do reviewers use for historic projects?
Los Altos requires projects to comply with the Secretary of the Interior's Standards for the Treatment of Historic Properties; that standard is the explicit review benchmark in § 14.93.060.A.3 and is referenced throughout the Mills Act requirements (§ 14.95.080) .
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