Bolthole Index

Santa Clara County, California

Building permits, zoning and septic rules in Monte Sereno, California

Building work inside Monte Sereno, California city limits needs a permit from the City's Building Department, and larger projects go through online plan check1. Monte Sereno sets its own zoning, with R-1-8, R-1-20 and R-1-44 single-family districts2. Septic permits for unsewered property anywhere in Santa Clara County come from the county Department of Environmental Health, and most city lots must connect to sewer34.

At a glance

Building permit
City permit required; minor permits online, larger work through plan check1
Zoning
City zoning: R-1-8, R-1-20 and R-1-44 residential districts2
Minimum lot
8,000, 21,780 or 43,560 square feet depending on district567
Sewer and septic
Sewer required where available; septic permits from Santa Clara County Environmental Health43
Plan check
About three weeks for the first review8
Owner-builder
Allowed with an owner-builder declaration for applicants exempt from contractor licensing9
Floodplain
Development in special flood hazard areas has added requirements10

Who to call

Building permits

City of Monte Sereno Building Department

Building permits, plan checking and inspections inside Monte Sereno city limits (phone is the City Hall main line shown on the page); the Planning Department at [email protected] handles land use applications

(408) 354-7635

[email protected]

18041 Saratoga-Los Gatos Road, Monte Sereno, CA 95030

Septic permits

Santa Clara County Department of Environmental Health, Land Use Program

Onsite wastewater treatment system (septic) permits for new construction and repairs in Santa Clara County where public sewer is not available

Contact details are copied from each office’s official page and were checked against it on October 10, 2026.

Off-grid gear

Going off-grid in Monte Sereno means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in Monte Sereno, California?

Yes. Building work inside Monte Sereno city limits needs a City permit, and the City separates minor permits from permits that need plan checking1. Minor permits are available online for work such as electrical panels, EV chargers, reroofs, sewer line replacement, water heaters and water pipes1. Since January 3, 2024, every new application that needs plan check must be submitted online with plans, an application and a plan-check deposit1. Construction is then inspected on site, and inspections can be scheduled online11. A property owner can apply as owner-builder by declaring an exemption from the Contractors' State License Law on the application9. The City has not published a certificate-of-occupancy rule that we could find, so ask the Building Department12.

Who issues building permits in Monte Sereno, and how do you reach them?

The City of Monte Sereno Building Department issues building permits, does plan checking and inspects work inside city limits12. Its front counter and Planning Department share City Hall at 18041 Saratoga-Los Gatos Road; the main line is (408) 354-763512. Inside city limits, Santa Clara County's building department does not issue building permits, because the county's permit rules cover unincorporated land only13. Septic permits are a separate matter and stay with the county3.

What do plan check and permit deposits involve in Monte Sereno?

Plan-check deposits are paid by credit card at submittal, are not refundable, and are credited toward the final permit fees14. The City's 2025 submittal document lists deposits from $150 to $10,000 depending on project scope, including $4,000 for an accessory dwelling unit and $6,000 for a new house of up to 2,000 square feet14. Submittals may require plans, structural calculations, Title 24 energy calculations, hydrology calculations, geotechnical reports and a stormwater form8. The initial plan check takes approximately 3 weeks, and resubmittals approximately 2 weeks8.

Does Monte Sereno have zoning, and what does it mean for lot size and setbacks?

Monte Sereno publishes its own zoning districts, including the R-1-8, R-1-20 and R-1-44 Residential Districts2. Minimum lot area is 8,000 square feet in R-1-8, 21,780 square feet in R-1-20 and 43,560 square feet in R-1-44, each unless the slope density formula in the Subdivision Title requires more567. In R-1-8, a single-story house needs a 25-foot front setback and 6-foot interior side setbacks15. In R-1-20 the single-story front setback is 30 feet and the interior side setback is 15 feet16. In R-1-44 the single-story interior side setback is 20 feet17. Setbacks grow with lot area above each district's minimum, and both allowed and proposed structural and impervious coverage must be shown on permit plans18. We could not confirm a minimum dwelling size or a tiny-home rule for Monte Sereno; ask the Planning Department12.

How do septic permits and sewer work in Monte Sereno?

Most Monte Sereno property is expected to use sewer. Where sewer is available within 300 feet, septic is not the stated alternative, and a property already connected to sewer must show proof of connection before the building permit is issued4. Projects with plumbing work typically also need a permit from the West Valley Sanitation District, with a copy included in the building permit submittal4. Where public sewer is not available, Santa Clara County's Department of Environmental Health permits onsite wastewater systems1920. Soils are a poor match for drain fields: about 1% of Santa Clara County soils lack severe limits for a conventional drain field, so expect an engineered system21.

Building a home in Monte Sereno: the steps, in order

  1. Confirm the lot's zoning district and its lot-size, setback and coverage standards2.
  2. Confirm sewer service; if the lot is unsewered, start a septic application with Santa Clara County Environmental Health1920.
  3. Prepare plans and any geotechnical, hydrology and energy reports the City's submittal checklist requires8.
  4. Submit the application and plan-check deposit online to the Building Department112.
  5. Get a West Valley Sanitation District permit if the project includes plumbing work4.
  6. Schedule inspections online as work proceeds11.

What stays with Santa Clara County, and what to check before you buy

The City decides building permits and zoning inside Monte Sereno, while septic permits for unsewered property stay with Santa Clara County Environmental Health3. Development in special flood hazard areas must minimize flood damage and provide adequate drainage, and manufactured homes and recreational vehicles have extra zone-specific requirements10. County rules on RVs, accessory dwellings and wells apply to unincorporated land, so confirm Monte Sereno's own rules before relying on them13. Typical home values are county-level and high: about $1,624,356 in Santa Clara County22.

Watch-outs

  • Plan-check applications must be submitted online, with a nonrefundable deposit credited to final permit fees14.
  • We could not confirm Monte Sereno rules for certificate of occupancy, wells, tiny homes, RV or camping use, or short-term rentals; ask the Building Department or Planning Department12.

Sources

  1. Building and Planning Departments (Monte Sereno), quoted and re-checked
  2. R-1-8 Residential District (Monte Sereno), quoted and re-checked
  3. Onsite Wastewater Treatment System (OWTS), quoted and re-checked
  4. Other approvals that may be needed for construction (Monte Sereno), quoted and re-checked
  5. R-1-8 Residential District (Monte Sereno), quoted and re-checked
  6. R-1-20 Residential District (Monte Sereno), quoted and re-checked
  7. R-1-44 Residential District (Monte Sereno), quoted and re-checked
  8. Building Permit Submittal Requirements (Monte Sereno), quoted and re-checked
  9. Building Permit Application (Monte Sereno), quoted and re-checked
  10. Standards for subdivisions and other proposed development (Monte Sereno), quoted and re-checked
  11. Building and Planning Departments (Monte Sereno), quoted and re-checked
  12. City of Monte Sereno Building Department (montesereno.org)
  13. Apply for a Building Permit, quoted and re-checked
  14. Building Permit Submittal Requirements (Monte Sereno), quoted and re-checked
  15. R-1-8 Residential District (Monte Sereno), quoted and re-checked
  16. R-1-20 Residential District (Monte Sereno), quoted and re-checked
  17. R-1-44 Residential District (Monte Sereno), quoted and re-checked
  18. Building Permit Submittal Requirements (Monte Sereno), quoted and re-checked
  19. Other approvals that may be needed for construction, quoted and re-checked
  20. Santa Clara County Department of Environmental Health, Land Use Program (deh.santaclaracounty.gov)
  21. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  22. Typical home value (Zillow): Bolthole Index county data

Written October 10, 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 Monte Sereno

Monte Sereno’s own rules

  • Building permitLimited

    Building work inside Monte Sereno city limits; the City distinguishes minor permits from permits requiring plan checking.

    • Minor permits are available online for listed work such as electrical panels, EV chargers, reroofs, sewer line replacement, temporary power, water heaters, and water pipes.
    • New applications requiring plan checking must be submitted online effective January 3, 2024, with plans, a completed application, and a plan-check deposit fee.
    “Effective January 3, 2024, all new applications for building permits that require a plan check shall be submitted online.”
  • Owner-builder exemptionConditional

    Property-owner applicants for construction permits inside Monte Sereno city limits.

    • The applicant must qualify for an exemption from the Contractors’ State License Law and complete the owner-builder declaration.
    • The application also states that the applicant agrees to comply with applicable city and county ordinances and state laws and authorizes inspection access.
    “I hereby affirm under penalty of perjury that I am exempt from the Contractors’ State License Law for the reason(s) indicated below by the checkmark(s) I have placed next to the applicable item(s)”
  • InspectionsRequired

    Construction subject to Monte Sereno building permitting.

    • The City administers the California Building Code through on-site inspections; inspection scheduling is available online.
    “The Building Department is responsible for administering the California Building Code requirements through plan checking, building permits, and on-site inspections.”
  • Zoning districtsPublished

    Monte Sereno city zoning districts.

    • The fetched official code sections publish at least R-1-8, R-1-20, and R-1-44 Residential District regulations.
    • The fetched selection does not establish that these are the only districts.
    “R-1-8 Residential District. [...] The following development standards shall apply in R-1-8 Districts:”
  • Lot coverageDistrict specific (with conditions)

    Development inside Monte Sereno city limits; structural and impervious coverage are governed by the applicable zoning district.

    • The fetched permit submittal form requires both allowed and proposed impervious and structural coverage to be shown.
    • Numeric coverage limits were not present in the fetched district excerpts.
    “Show total lot area, allowed impervious coverage, proposed impervious coverage, allowed structural coverage, and proposed structural coverage (See Development Standards handout)”
  • Mandatory utility hookupSewer (with conditions)

    New construction and applicable plumbing work inside Monte Sereno city limits.

    • Where sewer is available within 300 feet, septic is not the stated alternative; where a property is already connected to sewer, proof of sewer connection is required before building-permit issuance.
    • Monte Sereno permit submittal requirements state that, when required, a West Valley Sanitation District permit must be obtained, typically for plumbing work.

    sewer availability threshold: < 300 feet (County page states septic is required where sewer is not available within 300 feet.)

    “When required (typically, any project that includes plumbing work), a permit from the West Valley Sanitation District shall be obtained and a copy included with the building permit submittal.”
  • Building in a floodplainRequired

    Development, subdivisions, manufactured homes, and recreational vehicles in Monte Sereno special flood hazard areas.

    • Development proposals greater than 50 lots or five acres, whichever is lesser, must identify special flood hazard areas and base flood elevations and provide required elevation and certification information.
    • All development must minimize flood damage, provide adequate drainage, and construct public utilities to minimize flood damage.
    • Manufactured homes and recreational vehicles have additional zone-specific requirements.

    large-development threshold: 50 lots or 5 acres, whichever is lesser (Section 10.21.190(A).)

    “All new subdivision proposals and other proposed development, including proposals for manufactured home parks and subdivisions, greater than fifty (50) lots or five (5) acres, whichever is the lesser, shall: 1. Identify the special flood hazard areas (SFHA) and base flood elevations (BFE).”
  • Permit feesPublished (with conditions)

    Monte Sereno building permit plan-check submissions.

    • Deposits are paid by credit card at submittal, are nonrefundable, and are credited toward final permit fees.
    • The 2025 submittal document lists deposits from $150 to $10,000 depending on project scope.

    plan-check deposit range: 150-10000 USD (Project-scope dependent.) · ADU or 801-2,000 sq. ft. remodel / 401-1,000 sq. ft. addition deposit: 4000 USD (As listed in the revised 9/2025 schedule.) · new house up to 2,000 sq. ft. deposit: 6000 USD (As listed in the revised 9/2025 schedule.)

    “The following deposits shall be paid by credit card at the time of submittal. Deposit fees are not refundable but are credited toward the final permit fees.”
  • Permit processPublished (with conditions)

    Monte Sereno building permit applications requiring plan checking.

    • Applications and deposits are submitted online.
    • Submittals may require plans, structural calculations, Title 24 energy calculations, hydrology calculations, geotechnical reports, a geotechnical conformance letter, and a C3 stormwater form.
    • Initial plan check is approximately three weeks; resubmittals approximately two weeks.

    initial plan check: 3 weeks (Approximate.) · resubmittal review: 2 weeks (Approximate.)

    “The initial building plan check process is approximately three weeks from the date of the initial submittal. Resubmittals are reviewed within approximately two weeks from the date of re-submittal.”

Rules another office applies inside Monte Sereno

Monte Sereno does not set these itself; the county, a health district or the state does, and they apply to every address inside its limits.

  • Minimum lot sizeSpecified

    R-1-20 Residential District inside Monte Sereno city limits.

    • The slope density formula in the Subdivision Title may require a different minimum.
    • Minimum frontage is 100 feet on a public or private street.

    minimum lot area: >= 21780 square feet (Or the minimum required by the slope density formula.)

    “The minimum lot area shall be twenty-one thousand seven hundred eighty (21,780) square feet or the minimum as required by the slope density formula as set forth in the Subdivision Title of this Code.”
    2 more reviewed findings on this topic
    • Specified — R-1-8 Residential District inside Monte Sereno city limits.
      “The minimum lot area shall be eight thousand (8,000) square feet or the minimum as required by the slope density formula as set forth in the Subdivision Title of this Code.”
    • Specified — R-1-44 Residential District inside Monte Sereno city limits.
      “The minimum lot area shall be forty-three thousand five hundred sixty (43,560) square feet or the minimum as required by the slope density formula as set forth in the Subdivision Title of this Code.”
  • SetbacksSpecified

    R-1-20 Residential District, single-family buildings inside Monte Sereno city limits.

    • Setbacks increase by five feet for each 10,000 square feet above the minimum lot area.

    front single-story: >= 30 feet · front second-story: >= 40 feet · side interior single-story: >= 15 feet · side interior second-story: >= 20 feet · rear single-story: >= 30 feet · rear second-story: >= 40 feet

    “The minimum front setback shall be as follows: a. Single-story building: Thirty (30) feet. b. Second-story portion of building: Forty (40) feet. [...] The minimum side interior setback shall be as follows: a. Single-story building: Fifteen (15) feet. b. Second-story portion of building: Twenty (20) feet. [...] The minimum rear setback shall be as follows: a. Single-story building: Thirty (30) feet. b. Second-story portion of building: Forty (40) feet.”
    2 more reviewed findings on this topic
    • Specified — R-1-8 Residential District, single-family buildings inside Monte Sereno city limits.
      “The minimum front setback shall be as follows: a. Single-story building: Twenty-five (25) feet. b. Second-story portion of building: Thirty (30) feet. [...] The minimum side setback shall be as follows: a. Single-story building: Six (6) feet. b. Second-story portion of building: Ten (10) feet. [...] The minimum rear yard shall be as follows: a. Single-story building: Thirty (30) feet. b. Second-story portion of building: Thirty (30) feet.”
    • Specified — R-1-44 Residential District, single-family buildings inside Monte Sereno city limits.
      “The minimum front setback shall be as follows: a. Single-story building: Thirty (30) feet. b. Second-story portion of building: Forty-five (45) feet. [...] The minimum side interior setback shall be as follows: a. Single-story building: Twenty (20) feet. b. Second-story portion of building: Forty (40) feet. [...] The minimum rear setback shall be as follows: a. Single-story building: Thirty (30) feet. b. Second-story portion of building: Forty (40) feet.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Monte Sereno or Santa Clara County directly.

  • Certificate of occupancy — Certificate-of-occupancy requirements for buildings inside Monte Sereno city limits.
  • Minimum dwelling size — Minimum dwelling size inside Monte Sereno city limits.
  • Camping on your land — Temporary camping on private land inside Monte Sereno city limits.
  • Tiny homes — Tiny-home occupancy inside Monte Sereno city limits.
  • Septic inspection — Inspection requirements for individual septic systems inside Monte Sereno city limits.
5 more unanswered
  • Off-grid sanitation
  • Well permit
  • Agricultural exemption
  • Driveway access
  • 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 Monte Sereno 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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