Local zoning · Los Altos Hills

Los Altos Hills — Zoning

Q: What can I build on an R‑A lot in Los Altos Hills?

You can build a primary single‑family dwelling and accessory uses such as ADUs, agricultural uses, residential care, and certain day care homes where listed. The R‑A article lists permitted primary and accessory uses; numeric development limits are in Article 5 and some proposals (e.g., conditional uses) must meet Site Development findings. § 10‑1.701–§ 10‑1.704 .

Q: Do I need a zoning permit in Los Altos Hills?

Yes. A zoning permit from the Planning Officer is required for new buildings, relocation of structures, alterations that increase external dimensions, or a change in the use of land. No building permit or site development permit will be issued until the zoning permit is obtained. § 10‑1.310 .

Q: Are ADUs allowed in Los Altos Hills?

Yes. Accessory dwelling units (ADUs) are permitted on any lot with a primary single‑family dwelling and are regulated by Article 14 of the code; the ADU article controls over conflicting provisions in Title 10. § 10‑1.702(k) and Article 14.

Q: Where do I find parking requirements for a project?

Parking rules are in Article 6 of Title 10; the R‑A article refers to Article 6 for off‑street parking requirements. Review the town’s parking standards and submit parking plans with your application. § 10‑1.705 and Article 6.

Zoning under the Los Altos Hills local zoning and planning code, with the controlling citations.

Ask a question free See coverage

Last reviewed: July 2, 2026

Overview

This page summarizes what the Town of Los Altos Hills zoning ordinance (Title 10) actually says about zoning districts, the official zoning map, permitted uses, and the process that governs changes and exceptions. For municipal context, see the town overview at Los Altos Hills zoning & planning overview. The ordinance establishes two districts — Residential‑Agricultural (R‑A) and Open Space Reserve (OSR) — and ties dimensional rules to Article 5 and site development procedures to the Site Development articles. § 10‑1.301 and § 10‑1.302 are the controlling adoption rules.

How Los Altos Hills organizes Zoning

The zoning ordinance is codified in Title 10 (the Zoning Law of the Town of Los Altos Hills). § 10‑1.101 through the rest of Title 10 set the scope and organization.
The Town establishes specific districts and adopts a single official “Zoning Map for the Town of Los Altos Hills, California” by reference; the map may be divided into section maps and is amended by ordinance. § 10‑1.301–§ 10‑1.304.

First, the ordinance creates the districts; second, it adopts the map that shows where they apply. Uncertainties in map boundaries are handled by rules and by referral to the Planning Commission. § 10‑1.305.

(Throughout this page I link to related town guidance pages where the topic is naturally discussed: Los Altos Hills Development Standards, Los Altos Hills Parking, Los Altos Hills Design Review, Los Altos Hills Overlay Districts, Los Altos Hills ADUs, and the California Building Standards Code.)

District-by-district breakdown

Residential‑Agricultural (R‑A)

Purpose and where it applies

The Town’s primary default zone for land inside municipal boundaries is Residential‑Agricultural (R‑A); land not otherwise classified defaults to R‑A. § 10‑1.301 and § 10‑1.307.

Typical permitted uses

Primary dwellings (single‑family), agriculture and limited institutional/residential support uses such as employee/farmworker housing, residential care, transitional and supportive housing, and small family day care homes are allowed as primary or accessory uses where listed. See § 10‑1.701 and § 10‑1.702.
Accessory Dwelling Units (ADUs) are specifically permitted on lots with a primary single‑family dwelling and are regulated by Article 14 (they are governed by the ADU article and its rules override conflicting provisions). § 10‑1.702(k) and Article 14.

Uses expressly prohibited or restricted

Commercial cannabis activities are prohibited in R‑A except personal amounts and subject to restrictions; see § 10‑1.706 for the Town’s cannabis prohibitions and limits.

Dimensional and development controls (how standards are applied)

The R‑A district references Article 5 for area, coverage, height, and setback limitations; the code does not restate all numeric values in the R‑A article — instead it calls Article 5. § 10‑1.704 (see Article 5).
A notable limit that applies to development intensity: the ordinance caps combined ground coverage of structures, roadways, parking areas, and other impervious facilities at 40% of the net lot area for conditional uses (this constraint is included under the R‑A provisions). § 10‑1.701.
For numeric parcel‑size minimums, setbacks, heights and floor‑area definitions you must consult Article 5 (Article 5 section headings: § 10‑1.501 minimum parcel size; § 10‑1.503 floor area; § 10‑1.504 height; § 10‑1.505 setback lines). The ordinance points to Article 5 rather than repeating values in the R‑A article.

Practical notes

Only one primary dwelling is generally permitted per lot in many contexts (Town policies about parcel size and allowed dwellings are enforced via site development and conservation‑easement provisions where applicable). Verify with the Planning Department for parcels with special election or land use history (e.g., recorded special provisions). § 10‑1.701 and later articles.

Open Space Reserve (OSR)

Purpose and where it applies

The Open Space Reserve (OSR) district preserves land for open space, forestry, grazing and related passive/agricultural uses; the map shows which parcels are OSR. § 10‑1.801–§ 10‑1.803.

Typical permitted uses

Agriculture (horticulture and grazing), forest preserves, and other open space uses are allowed as primary uses in OSR. Accessory structures are limited to those necessary for the permitted primary uses. § 10‑1.801–§ 10‑1.802.

Uses expressly prohibited

Commercial cannabis activities and dispensaries are prohibited in OSR, except for limited personal cultivation allowances described in the cannabis provisions; see § 10‑1.804.

Dimensional and development controls

Like R‑A, the OSR article refers to Article 5 for area, coverage, height, and setback limitations; proposed structures and fences are limited by the same Article 5 rules. § 10‑1.803 / Article 5.

Where each district appears on the official map

The official Zoning Map for the Town of Los Altos Hills, California (adopted by reference) identifies the parcels in R‑A versus OSR; amendments to the map are made by ordinance (see § 10‑1.302–§ 10‑1.304). If a parcel is not shown or the district is in doubt, the land defaults to R‑A until reclassified. § 10‑1.302–§ 10‑1.307.

Quick reference table — key decision standards and code references

Topic / Decision item	What the ordinance says (short)	Code reference
Districts established	Residential‑Agricultural (R‑A) and Open Space Reserve (OSR) are the town’s zoning districts.	§ 10‑1.301
Official zoning map	The map is adopted by reference; section maps may be used; amendments by ordinance.	§ 10‑1.302–§ 10‑1.304
Zoning permit required	A zoning permit is required for new buildings, expansions that increase external dimensions, or a change of use.	§ 10‑1.310
R‑A primary permitted uses	Primary dwellings, agriculture, emergency shelters (with standards), employee/farmworker housing, residential care.	§ 10‑1.701
ADUs	ADUs are permitted on lots with a primary single‑family unit and regulated by Article 14 (ADU article controls).	§ 10‑1.702(k); Article 14
OSR permitted uses	Agriculture, forest preserves and other open space uses; accessory structures limited to those necessary for primary uses.	§ 10‑1.801–§ 10‑1.803
Development intensity cap	Combined ground coverage (structures, roadways, parking, other impervious) shall not exceed 40% of net lot area for conditional uses.	§ 10‑1.701
Boundary uncertainty rules	Where the map is ambiguous, boundaries follow centerline of streets or property lines; the Planning Commission can resolve disputes.	§ 10‑1.305

Checklist — what an applicant must satisfy (zoning-specific)

Confirm the parcel zoning on the official town Zoning Map and whether any recent ordinance amended that parcel’s designation; if unclear, request a boundary determination. § 10‑1.302–§ 10‑1.305.
Obtain a zoning permit before construction, alteration that increases external dimensions, or change of use. § 10‑1.310.
Confirm permitted vs. conditional uses for the district (R‑A or OSR) and whether a conditional use permit (CUP) or variance will be necessary; prepare findings per § 10‑1.1007 for CUP/variance.
Check Article 5 for numerical standards (minimum parcel size, setbacks, height, floor area) referenced by district articles; include those standards in plans. § 10‑1.704 and Article 5 headings § 10‑1.501–§ 10‑1.505.
If proposing accessory dwelling units, follow Article 14 requirements; ADU rules supersede conflicting Title 10 provisions. § 10‑1.702(k) and Article 14.
For parking calculations and layout expectations, consult the Town’s parking standards and provide parking consistent with Article 6 requirements. § 10‑1.705 and Article 6.
Prepare site documentation for Site Development Authority review per the application checklists (landscape plans, erosion control, grading, topographic/site maps). See Article 2 / Site Development application requirements.

(Links: reference the town’s Development Standards, Parking, and Design Review pages for procedural checklists.)

Risks & Ambiguities

Issue	Why it matters	What to verify
Boundary ambiguity on zoning map	Map scale/notations can produce different interpretations of which district a parcel sits in; affects allowed uses.	Verify exact parcel classification with the Planning Department and request a formal boundary determination per § 10‑1.305.
Numeric standards not restated in district articles	R‑A and OSR refer to Article 5 rather than listing setbacks, heights, minimum parcel sizes.	Pull Article 5 (§ 10‑1.501–§ 10‑1.505) for the numeric values. If not found in your copies, ask Planning staff.
ADU regulatory interplay	ADUs are governed by Article 14 and may differ from other accessory‑use rules.	Use Article 14 and state ADU law; confirm which Article controls (the code says Article 14 controls) § 10‑1.702(k).
Development area / impervious coverage	The ordinance sets a 40% cap on combined impervious ground coverage for conditional uses, but how it’s measured can affect site design.	Confirm calculation method and whether exceptions or reductions apply under site development rules. § 10‑1.701.
Pre‑zoning and annexation rules	Unincorporated lands may be prezoned; annexed lands default to OSR until classified.	If your parcel was annexed or is near an annexation line, verify the effective zoning per § 10‑1.306. Not found in detail in retrieved materials—verify with the Town.

Plain‑English Summary

Los Altos Hills has two zoning districts: R‑A (where most homes and agricultural uses are allowed) and OSR (for open space/agricultural preservation). The official map (adopted by reference) shows which parcels are in which district; for rules on setbacks, height, minimum lot size and floor area you must consult Article 5 and the Site Development application standards. Zoning permits are required before building or changing a use; ADUs are permitted under Article 14 but must comply with that article’s rules. Verify parcel‑specific numeric limits with Planning before designing. § 10‑1.301–§ 10‑1.310, Article 5, and the ADU article are the controlling provisions.

Information Gaps

Specific numeric values for minimum parcel size, exact setback distances, height limits, and floor area were referenced by Article 5 headings (§ 10‑1.501–§ 10‑1.505) but the numeric contents were not present in the retrieved materials. Not found in retrieved materials.
The complete text of Article 14 (ADU rules) (full thresholds and objective standards) was referenced but not fully returned in the retrieved chunks. Not found in retrieved materials.
Any recent map amendments or ordinance changes after the downloaded copy (the copy notes it was downloaded from eCode360) should be checked on the Town website or with Planning. Verify with the jurisdiction.

Source References

Los Altos Hills Municipal Code (Title 10 — Zoning), eCode360 download: various sections cited in this page (examples: § 10‑1.101, § 10‑1.301, § 10‑1.302, § 10‑1.305, § 10‑1.310, § 10‑1.701, § 10‑1.702, § 10‑1.704, § 10‑1.801–§ 10‑1.804, § 10‑1.501–§ 10‑1.505). See the ordinance excerpts used above.

Sources

Retrieved passages

Los Altos Hills Zoning Code (chapter as) High relevance
Los Altos Hills Zoning Code (Article 7) High relevance
Los Altos Hills Zoning Code (Section 10-1.301) High relevance
Los Altos Hills Zoning Code (Section Zoning) High relevance
Los Altos Hills Zoning Code (§ 10-1.704.) High relevance
Los Altos Hills Zoning Code (§ 1) High relevance
Los Altos Hills Zoning Code (§ 10-1.503.) High relevance
Los Altos Hills Zoning Code (§ 10-1.801) High relevance

Cited sections

Official Los Altos Hills code library

Frequently asked questions

What can I build on an R‑A lot in Los Altos Hills?

You can build a primary single‑family dwelling and accessory uses such as ADUs, agricultural uses, residential care, and certain day care homes where listed. The R‑A article lists permitted primary and accessory uses; numeric development limits are in Article 5 and some proposals (e.g., conditional uses) must meet Site Development findings. § 10‑1.701–§ 10‑1.704.

What are Los Altos Hills setback requirements?

Setbacks are controlled by the Article 5 development standards (area, coverage, height and setback limitations). The R‑A and OSR articles refer applicants to Article 5 for the specific setback dimensions: see § 10‑1.504 and related sections. The retrieved materials show the cross‑references but the numeric setback distances were not present in the retrieved excerpts. § 10‑1.704; Article 5 (§ 10‑1.501–§ 10‑1.505). Not found in retrieved materials.

Do I need a zoning permit in Los Altos Hills?

Yes. A zoning permit from the Planning Officer is required for new buildings, relocation of structures, alterations that increase external dimensions, or a change in the use of land. No building permit or site development permit will be issued until the zoning permit is obtained. § 10‑1.310.

Are ADUs allowed in Los Altos Hills?

Yes. Accessory dwelling units (ADUs) are permitted on any lot with a primary single‑family dwelling and are regulated by Article 14 of the code; the ADU article controls over conflicting provisions in Title 10. § 10‑1.702(k) and Article 14.

What is the maximum lot coverage or impervious limit?

The code states that the combined ground coverage of structures, roadways, parking areas, and other impervious facilities shall not exceed 40% of the net area of the lot (this is included under the R‑A/conditional uses provisions). Confirm measurement methodology with Planning when designing. § 10‑1.701.

If my property isn’t shown on the map, what zoning applies?

Land not specifically included within a district defaults to Residential‑Agricultural (R‑A) until otherwise classified. The ordinance makes this default explicit. § 10‑1.307.

How are disputes over zoning map boundaries resolved?

Where uncertainty exists, the ordinance provides mapping rules (e.g., boundary follows centerline of street or property line) and empowers the Planning Commission to determine boundary locations after an application or on its own motion. § 10‑1.305.

Do I need a conditional use permit or variance to change a use?

If the proposed use is not a permitted primary or accessory use for the district, a conditional use permit or variance may be required. Conditional uses/variances require specific findings and follow the procedures set out in Article 10 (e.g., § 10‑1.1007 and appeal rules in § 10‑1.1009).

Where do I find parking requirements for a project?

Parking rules are in Article 6 of Title 10; the R‑A article refers to Article 6 for off‑street parking requirements. Review the town’s parking standards and submit parking plans with your application. § 10‑1.705 and Article 6.

Can I plant or cultivate cannabis on my R‑A lot?

Personal indoor and outdoor cultivation in amounts allowed by state law is permitted under limits (must be secured, not visible from right‑of‑way, not in setbacks or town easements); commercial cannabis activities and dispensaries are prohibited. See § 10‑1.706. ---

Ask about any Los Altos Hills property

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

Start Free Trial