Bolthole Index

Santa Clara County, California

Building permits, zoning and septic in the Town of Los Altos Hills, California

The Town of Los Altos Hills, California requires building permits for home construction and regulated alterations, repairs and demolition.1 The Town administers local zoning, while Santa Clara County Department of Environmental Health processes septic permits inside town limits.23 New residences and major additions may require abandoning an existing septic tank and connecting to public sewer.4

At a glance

Building permits
Required; apply to the Town Building Department15
Zoning
Town zoning applies inside town limits2
Septic permits
Santa Clara County Department of Environmental Health3
ADU setbacks
In R-A, new ADUs need 40-foot front and 4-foot side/rear setbacks6
Subdivision lot size
Each subdivision lot must contain at least 1 net acre within the qualifying circle; slope and building-site requirements also apply7
Occupancy
Final building inspection and a certificate of occupancy are required89
Owner-builder
California contractor-license exemption is conditional; Town building permits still apply101

Who to call

Building permits

Town of Los Altos Hills Building Department

Town building-plan review, building permits and inspections

650-947-2501

[email protected]

26379 Fremont Road Los Altos Hills , CA 94022

Online permits →

Zoning

Town of Los Altos Hills Planning Department

Town zoning and planning questions

650-941-7222

[email protected]

26379 Fremont Road Los Altos Hills, CA 94022

Septic permits

Santa Clara County Department of Environmental Health — Land Use

Septic feasibility, design review, permits and installation inspections inside Los Altos Hills

Roads & driveways

Town of Los Altos Hills Public Works Department

Encroachment permits, infrastructure and engineering questions

650-941-7222

26379 Fremont Road Los Altos Hills, CA 94022

Contact details are copied from each office’s official page and were checked against it on October 11, 2026.

Off-grid gear

Going off-grid in Town of Los Altos Hills means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in the Town of Los Altos Hills, CA?

Los Altos Hills requires a Town building permit for construction, alteration, repair, relocation, demolition, occupancy changes and regulated electrical, gas, mechanical or plumbing work.1 The Town enforces applicable California building standards and has local building-regulation amendments.11

Ask the Building Department to confirm any small-structure exemption before ordering a shed: the residential guide lists limited exemptions, but the Town’s project list separately says a new building of any type or size needs a building permit.1 Permitted work requires construction inspections, including a final inspection before occupancy; a certificate of occupancy is also required before a building is used or occupied.89

Who issues building permits in the Town of Los Altos Hills?

The Los Altos Hills Building Department reviews architectural and structural plans and conducts building inspections.12 Contact the Building Department at 650-947-2501 or [email protected] for building-permit and inspection questions.12 Contact the Town Planning Department at [email protected] for the parcel’s zoning questions.13

Building-permit applications go through the Town’s eTRAKiT portal, with an email-submittal option for listed smaller projects such as kitchen and bathroom remodels, water heaters and reroofs.5 Ask Building for a current fee estimate: the available building fee schedule is labeled FY 2023/24, and multiple review actions can generate cumulative fees and replenishable deposits.14

Does the Town of Los Altos Hills have zoning and minimum lot sizes?

Los Altos Hills has local zoning and Town development standards; use the Town Planning Department for land inside town limits.213 For residential subdivision lots, the Town requires at least 1 net acre within a qualifying circle, along with a building-site circle and slope-density calculations.7 That subdivision standard should not be treated as a blanket answer about every existing parcel.7

Minor and major subdivisions require a tentative map, with completeness review, environmental review as required and a Planning Commission public hearing.15 Each residential lot created through subdivision must be capable of safe vehicular access by a private or common driveway meeting Town standards.16 Ask Planning to evaluate the proposed split and building site together.715

How do septic permits work inside the Town of Los Altos Hills?

Santa Clara County Department of Environmental Health processes all onsite wastewater treatment system, or septic, permitting inside Los Altos Hills.3 County Environmental Health evaluates sites and soils, reviews proposed septic designs, issues septic permits and inspects installation.17 Use the county’s Land Use contact map to find the specialist assigned to the property address.17

For a new residence or major addition, ask Town Building whether public sewer connection will require abandoning the existing septic tank; the Town generally defines a major addition as an increase of 900 square feet or more.4 A septic system’s feasibility and permit timing are questions for County Environmental Health, while any associated building-permit requirement is a separate Town Building question.3

Can you live in an RV or tiny home in the Town of Los Altos Hills?

We could not confirm a Los Altos Hills rule allowing residential RV occupancy, temporary camping or tiny-home occupancy on private land; ask Town Planning about the exact unit and intended use before buying.13 The Town’s R-A Residential Agricultural District does have published standards for new accessory dwelling units, but those standards alone do not establish permission to occupy an RV or a tiny home on wheels.26

For a new ADU in R-A, the published front setback is at least 40 feet, with side and rear setbacks of at least 4 feet.6 The base ADU height limit is 16 feet; up to 19 feet is described where onsite parking and side/rear setbacks of at least 30 feet are provided.18

Building a home in the Town of Los Altos Hills: what are the steps?

Follow the Town’s planning, engineering and building sequence, and resolve wastewater service before committing to the final home design.54

  1. Confirm necessary Planning and Engineering approvals with the Town.5
  2. Ask County Environmental Health about septic feasibility and timing, and ask Town Building whether sewer connection is required for the project.34
  3. Prepare working drawings, structural and energy calculations, and soils reports, then submit the building-permit application through eTRAKiT; separate dwelling units or structures need separate building permits.5
  4. Respond to plan-check comments and pay applicable fees and the final deposit when the building permit is ready for issuance.5
  5. Request construction inspections and obtain final inspection and the certificate of occupancy before moving in.89

What stays with Santa Clara County, and what should Los Altos Hills buyers check?

County Environmental Health remains the septic permitting authority inside Los Altos Hills, even though the Town handles building permits and local zoning.352 For land outside town limits, see the Santa Clara County guide: the county’s building-permit requirements apply to unincorporated land.19

Ask Town Public Works about encroachment permits and the project’s effects on roads, storm drainage and sanitary sewer infrastructure.20 We could not confirm the Town’s specific floodplain development requirements; ask Public Works to review the parcel and proposed work.20 California requires local permits before water-well construction, modification or destruction; confirm the applicable local well authority before arranging drilling in Los Altos Hills.21

Watch-outs

  • Confirm small accessory-structure exemptions with Los Altos Hills Building before construction because the Town’s published building-permit guidance differs on new small buildings.1
  • Budget using a current Town Building fee estimate rather than assuming the published FY 2023/24 schedule is the price for a new application.14
  • A new Los Altos Hills residence or major addition may trigger septic abandonment and public sewer connection.4
  • California’s owner-builder contractor-license exemption has conditions and does not remove the Los Altos Hills building-permit requirement.101

Sources

  1. 2019 Residential Building Guide (Town of Los Altos Hills), quoted and re-checked
  2. Municipal Code (Town of Los Altos Hills), quoted and re-checked
  3. Septic System/OWTS (Town of Los Altos Hills), quoted and re-checked
  4. Septic System/OWTS (Town of Los Altos Hills), quoted and re-checked
  5. 2019 Residential Building Guide (Town of Los Altos Hills), quoted and re-checked
  6. losaltoshills.ca.gov (Town of Los Altos Hills), quoted and re-checked
  7. Subdivision Application Packet (Town of Los Altos Hills), quoted and re-checked
  8. 2019 Residential Building Guide (Town of Los Altos Hills), quoted and re-checked
  9. 2019 Residential Building Guide (Town of Los Altos Hills), quoted and re-checked
  10. California Business and Professions Code Section 7044 (California statewide rule), quoted and re-checked
  11. Reach Codes (Town of Los Altos Hills), quoted and re-checked
  12. Town of Los Altos Hills Building Department (losaltoshills.ca.gov)
  13. Town of Los Altos Hills Planning Department (losaltoshills.ca.gov)
  14. Building Fee Schedule FY 2023/24 (Town of Los Altos Hills), quoted and re-checked
  15. Subdivision Application Packet (Town of Los Altos Hills), quoted and re-checked
  16. Subdivision Application Packet (Town of Los Altos Hills), quoted and re-checked
  17. Santa Clara County Department of Environmental Health — Land Use (deh.santaclaracounty.gov)
  18. losaltoshills.ca.gov (Town of Los Altos Hills), quoted and re-checked
  19. Apply for a Building Permit, quoted and re-checked
  20. Town of Los Altos Hills Public Works Department (losaltoshills.ca.gov)
  21. Well Standards (California statewide rule), quoted and re-checked

Written October 11, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for Town of Los Altos Hills

Town of Los Altos Hills’s own rules

  • Building permitRequired

    Construction, alteration, repair, relocation, demolition, occupancy changes, and regulated electrical, gas, mechanical, or plumbing work inside Los Altos Hills town limits.

    • The guide lists limited residential exemptions, including certain detached accessory structures not exceeding 120 square feet, fences not over 7 feet, certain retaining walls, water tanks, finish work, shallow prefabricated pools, and playground equipment.
    • The Town's permit-project list separately states that a new building of any type or size requires a permit.

    detached accessory structure exemption floor area: <= 120 sq ft (one-story detached accessory structures only)

    “shall first make application to the Building Official and obtain the required permit.”
  • Building code adoptedPartial

    Building work inside Los Altos Hills town limits; the Town has local building-regulation amendments and enforces applicable California building standards.

    • The Town's reach-code page describes amendments to the Building Regulations in the Municipal Code; the older residential guide states that the Building Department enforces California Building Standards Codes.
    “During the 2019 code cycle, the Council adopted the Town’s first local building energy reach code”
  • InspectionsRequired

    Permitted building work inside Los Altos Hills town limits.

    • Required inspections include foundation, slab/under-floor, rough plumbing/mechanical/gas/electrical, framing and masonry, lath and gypsum board, other inspections as required, special inspections, fire-resistance-rated construction inspections, and final inspection.
    • Final inspection is required before occupancy.
    “Final inspection shall be made after the permitted work is complete and prior to occupancy.”
  • Certificate of occupancyRequired

    Use or occupancy of buildings and changes in occupancy classification inside Los Altos Hills town limits.

    • The certificate is issued after the Building Official inspects the building or structure and finds no violations.
    • The certificate includes the permit number, address, owner, inspected portion, code edition, sprinkler information, and special stipulations or conditions.
    “No building or structure shall be used or occupied [...] until the building official has issued a certificate of occupancy therefore as provided herein.”
  • Local zoningPresent

    Land inside Los Altos Hills town limits; the Town maintains and publishes its own Municipal Code and zoning-related development standards.

    • The Town directs applicants to its Municipal Code and local planning process.
    “One ADU and/or one JADU are allowed on any property, regardless of lot size, in the R-A (Residential Agricultural) District”
  • Minimum lot sizeSpecified

    Residential lots created through subdivision inside Los Altos Hills town limits.

    • Each lot must contain at least one net acre within a circle no greater than 350 feet in diameter.
    • The subdivision packet also requires a building site within a 160-foot-diameter circle and slope-density calculations.

    minimum net area within qualifying circle: >= 1 acre (applies to each lot in the subdivision map requirements)

    “Each lot shall contain an area of at least one net acre within a circle no greater than three hundred fifty (350) feet in diameter;”
  • SetbacksSpecified

    New ADUs in the R-A Residential Agricultural District inside Los Altos Hills town limits.

    • Front setback from street frontages must be at least 40 feet.
    • Side and rear setbacks must be at least 4 feet.
    • Side and rear setbacks of at least 30 feet may qualify the ADU for additional floor area and height.

    front setback: >= 40 ft (street frontages) · side/rear setback: >= 4 ft (30 feet may qualify for additional floor area and height)

    “A new ADU shall have a front setback (street frontages) of at least 40 feet and side/rear setbacks of at least four (4) feet.”
  • Building heightSpecified

    New ADUs in the R-A Residential Agricultural District inside Los Altos Hills town limits.

    • Base ADU height limit is 16 feet.
    • Up to 19 feet is allowed when an onsite parking space and side/rear yard setbacks of at least 30 feet are provided.

    ADU height limit: 16 ft (up to 19 feet with onsite parking and 30-foot side/rear setbacks) · conditional ADU height: <= 19 ft (onsite parking and 30-foot side/rear setbacks required)

    “A new ADU has a height limit of 16 feet.”
  • Who permits septicCounty (with conditions)

    Onsite wastewater treatment systems serving property inside Los Altos Hills town limits; the Town identifies Santa Clara County DEH as the permitting authority.

    • The Town advises applicants to inquire with Santa Clara County Department of Environmental Health regarding permit-process duration and feasibility.
    • The Town Building Department separately handles questions about whether a building permit is required.
    “All Onsite Wastewater Treatment System (Septic System) permitting is processed by the County of Santa Clara Department of Environmental Health (DEH).”
  • Mandatory utility hookupSewer (with conditions)

    New residences and major additions on property inside Los Altos Hills town limits that are served by or can connect to the public sewer system.

    • The Town states that new residence and major addition projects may require abandonment of an existing septic tank and connection to public sewer.
    • The Town page does not state a universal distance threshold in the opened material.
    • A major addition is generally defined as an increase of 900 square feet or more to an existing single-family residence.

    major addition threshold: >= 900 sq ft (generally defined by the Town)

    “New Residence and Major Addition Projects may require abandonment of septic tank and connection to public sewer.”
  • Subdividing landRegulated (with conditions)

    Minor and major subdivisions inside Los Altos Hills town limits.

    • A tentative map is required for minor subdivisions of 4 lots or fewer and major subdivisions of 5 or more lots.
    • Maps must comply with the California Subdivision Map Act and Title 9 of the Town Municipal Code.
    • The process includes completeness review, CEQA review as required, distribution to staff and committees, and Planning Commission public hearing.

    minor subdivision threshold: <= 4 lots (tentative map required) · major subdivision threshold: >= 5 lots (tentative map required)

    “A tentative map is required for minor subdivisions (4 lots or fewer) and major subdivision (5 or more lots).”
  • Driveway accessRequired

    Residential lots created through subdivision inside Los Altos Hills town limits.

    • Each residential lot must be capable of safe vehicular access from a public or private road by a private or common driveway conforming to Town standards.
    “it shall be possible to provide safe vehicular access via a private or common driveway, conforming to the City standards”
  • Permit feesPublished (with conditions)

    Building permits and related planning/engineering review inside Los Altos Hills town limits.

    • The fee schedule is FY 2023/24 and was adopted via Resolution No. 77-23 effective October 21, 2023.
    • Multiple actions require cumulative fees.
    • Deposits must be replenished when exhausted and unused portions are refunded after final project review.
    • Building permit fees include a $240 base fee plus 0.9% of project valuation; plan review is 65% of permit fee.
    • Temporary certificate of occupancy fee is $500 and requires Planning and Building Director approval plus special circumstances.

    building permit base fee: 240 USD (plus 0.9% of project valuation) · building permit valuation modifier: 0.9 percent (project valuation provided by applicant and confirmed during initial plan review) · plan review fee: 65 percent of permit fee · temporary certificate of occupancy fee: 500 USD (Planning and Building Director approval and special circumstances required)

    “Building Fee Schedule FY 2023/24 Adopted via Resolution No. 77-23 – Effective Date: October 21, 2023”
  • Permit processPublished (with conditions)

    New residential construction and other building-permit work inside Los Altos Hills town limits.

    • Applicants must confirm necessary Planning and Engineering approvals.
    • Separate permits are required for each dwelling unit and/or structure.
    • Submittals include working drawings, structural calculations, energy calculations, and soils reports.
    • Plan-check comments may be issued; applicable fees and a final deposit are paid when the permit is ready for issuance.
    • Inspections must be called during construction and a final inspection must be scheduled before occupancy.
    • Beginning July 1, 2024, building permits must be submitted electronically through the Town eTrakit portal, except smaller permits that may be submitted by email as described by the Building Department.

    inspection advance notice: >= 24 hours (older residential guide procedure)

    “Beginning July 1st, 2024 All building permits must be submitted electronically through the Los Altos Hills eTrakit portal.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Town of Los Altos Hills or Santa Clara County directly.

  • Owner-builder exemption — Owner-builders performing construction inside Los Altos Hills town limits.
  • Zoning districts — Zoning districts inside Los Altos Hills town limits.
  • Minimum dwelling size — Primary dwellings inside Los Altos Hills town limits.
  • Lot coverage — Primary residential development inside Los Altos Hills town limits.
  • Living in an RV — Long-term or residential RV occupancy on private land inside Los Altos Hills town limits.
9 more unanswered
  • Camping on your land
  • Tiny homes
  • Manufactured homes
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Agricultural exemption
  • Building in a floodplain
  • Short-term rentals

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Town of Los Altos Hills publishes no rule on the point, not that none exists. Santa Clara County’s page lists the county offices to call.

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