Bolthole Index

Contra Costa County, California

Building permits, zoning and land rules in Martinez, California

Martinez, California issues building permits through the city Building Division and administers zoning through city Planning.12 Inside Martinez in Contra Costa County, septic systems and wells also require review by Contra Costa Environmental Health.3 New city building permit applications go through the online portal; RV living remains unconfirmed, so ask Planning before relying on it.12

At a glance

Building permits
City Building Division issues building permits inside city limits1
Zoning
City zoning districts; Planning is the zoning administrator42
Septic systems
Contra Costa Environmental Health review and OWTS construction permits35
RV living
Not confirmed; ask city Planning about the proposed parcel and occupancy2
ADU/JADU minimum size
150 square feet or the size needed for an efficiency unit, whichever is greater6
Private wells
County water-well permit application and licensed driller required7

Who to call

Building permits

City of Martinez Building Division — Permit Center

City building permit applications, plan review and inspection questions

(925) 372-3515

[email protected]

525 Henrietta Street

Online permits →

Zoning

City of Martinez Planning Division

City zoning administration and development proposal review

(925) 372-3515

525 Henrietta Street

Septic permits

Contra Costa Health — Environmental Health Land Use Program

County septic design review, construction inspection and well permits

925-608-5500

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 Martinez means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in Martinez, CA?

The Martinez Building Division issues building permits to homeowners and licensed contractors for construction inside city limits; ask the Permit Center which building approvals your proposed work requires.1 Martinez has adopted the 2025 California Building Code.8 A single-parcel residential development also needs a site development permit for non-building improvements such as grading, drainage, driveways and walkways.9 Improvements within public rights-of-way still require an encroachment permit.9 Martinez permit fees for work covered by its building-code chapter are set by City Council resolution, rather than a single fixed amount.10

Who handles building permits and zoning in Martinez?

For Martinez building permit questions, contact the city Permit Center at (925) 372-3515 or [email protected]; the counter is at 525 Henrietta Street.1 Martinez Planning serves as the city zoning administrator and reviews development proposals.2 City building permit applications must be submitted electronically through the online portal; solar applications continue through SolarAPP+ only.1 The Building Division email is for questions, and building permit applications sent there are not accepted.1 Ask the Permit Center about owner-builder paperwork and the inspections required for your specific project before submitting a building permit application.1

Does Martinez have zoning, and what are the lot and ADU rules?

Martinez publishes its own zoning districts, including residential and rural residential districts.4 In Martinez’s R-1.5 district, the minimum site area is 5,000 square feet; in RR-20.0, the minimum is 20,000 square feet.1112 Martinez subdivision maps must conform to city zoning requirements for land use, lot dimensions, parking and other applicable standards.13 Martinez ADUs and JADUs must be at least 150 square feet or large enough for an efficiency unit, whichever is greater; that rule does not establish the minimum size of a primary house.6 Newly constructed Martinez ADUs are exempt from the zoning or overlay district’s maximum lot coverage and floor-area ratio.14

How do septic permits and well permits work inside Martinez?

Contra Costa Environmental Health serves properties with septic systems and wells, including properties inside Martinez; projects involving those systems need Environmental Health-approved plans at application submittal.3 County OWTS construction permits cover new systems, alterations, replacements, abandonment and tank replacement.5 Permitted septic work requires inspections, approved plans kept at the job site, and written authorization before placing the system in service.15 The county water-well application requires a plot plan and a licensed well driller’s signature.7 Ask Environmental Health to evaluate sewage disposal early, and ask city Planning and the serving sewer agency about sewer connection requirements before treating septic as an option for a Martinez parcel.162

Can you live in an RV or tiny home on your land in Martinez?

We could not confirm a Martinez rule allowing long-term RV occupancy, temporary camping or a tiny home on wheels on private land; ask city Planning about the exact parcel, vehicle and intended use before buying.2 For a small permanent accessory dwelling instead, Martinez’s ADU/JADU minimum-size provision requires 150 square feet or the space needed for an efficiency unit, whichever is greater.6 That ADU provision does not answer RV occupancy or establish a minimum size for every primary dwelling.6 For land outside city limits, use the Contra Costa County guide: the county’s RV habitation restrictions cited there apply to unincorporated land.17

Building a home in Martinez: what are the steps, in order?

  1. Ask Martinez Planning to identify the parcel’s zoning and review the proposed development before finalizing a design.2
  2. For septic or well property, obtain Contra Costa Environmental Health plan approval for application submittal.3
  3. Discuss site development and any public-right-of-way improvements with the city; a site development permit covers non-building site improvements, while an encroachment permit remains separate.9
  4. Submit the city building permit application electronically through the online portal.1
  5. Arrange city building inspections through the Building Inspection Request Recorder, and obtain the separate required septic inspections when applicable.115

Before committing to a Martinez project in a flood zone, ask the city Building Division to review flood status and construction costs; the city evaluates those questions case by case.1

Watch-outs

  • Martinez building permit applications moved to electronic submission in September 2026; paper applications require an exceptional-circumstances approval from the Chief Building Official.1
  • We could not confirm Martinez’s general occupancy-certificate or owner-builder requirements; ask the city Building Division before planning move-in or self-managed construction.1
  • Contra Costa County zoning and building rules for unincorporated land do not answer a parcel inside Martinez city limits; city Planning administers Martinez zoning.182

Sources

  1. City of Martinez Building Division — Permit Center (cityofmartinez.org)
  2. City of Martinez Planning Division (cityofmartinez.org)
  3. contracosta.ca.gov, quoted and re-checked
  4. Title 22: Zoning - City of Martinez, CA (Martinez), quoted and re-checked
  5. OWTS Construction Permit Application, quoted and re-checked
  6. Chapter 22.43: Accessory Dwelling Units and Junior Accessory Dwelling Units (Martinez), quoted and re-checked
  7. Water Well Permit Application, quoted and re-checked
  8. Chapter 15.04: Building Code (Martinez), quoted and re-checked
  9. Chapter 15.04: Building Code (Martinez), quoted and re-checked
  10. Chapter 15.04: Building Code (Martinez), quoted and re-checked
  11. Chapter 22.12: Residential Districts (R and RR) (Martinez), quoted and re-checked
  12. Chapter 22.12: Residential Districts (R and RR) (Martinez), quoted and re-checked
  13. Chapter 21.02: General Provisions (Martinez), quoted and re-checked
  14. ecode360.com (Martinez), quoted and re-checked
  15. OWTS Construction Permit Application, quoted and re-checked
  16. Contra Costa Health — Environmental Health Land Use Program (cchealth.org)
  17. Contra Costa County Ordinance Code, Chapter 84-68, T-1 Mobile Home/Manufactured Home Park District, quoted and re-checked
  18. Planning and Zoning, 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 Martinez

Martinez’s own rules

  • Building code adoptedAdopted

    Construction inside Martinez city limits.

    • The City adopts the 2025 California Building Code by reference.
    • The adopted code is Part 2 of Title 24 and incorporates a California version of the 2024 International Building Code.
    • The section history lists Ordinance No. 1479 adopted November 19, 2025.

    building code edition: 2025 California Building Code (Volumes 1 and 2)

    “The City hereby adopts by reference the 2025 Edition of the California Building Code, Volumes 1 and 2, also known as Part 2 of Title 24 of the California Code of Regulations, which incorporates a California version of the 2024 International Building Code published by the International Code Council.”
  • InspectionsLimited

    Single-parcel residential and nonresidential development inside Martinez city limits, for non-building site improvements.

    • The cited requirement concerns plan checking and inspection of non-building site improvements, including grading, drainage, streets, driveways, parking lots, and walkways.
    • It does not by itself establish every building inspection requirement.
    “A site development permit shall be required for each single parcel residential and non-residential development for the plan checking and inspection of all non-building site improvements including grading, drainage, streets, driveways, parking lots, walkways, and other related improvements.”
  • Zoning districtsPublished

    Zoning districts inside Martinez city limits.

    • The municipal code publishes district designations and residential district provisions, including R, RR, and multiple district-specific chapters.
    “Chapter 22.08 DISTRICT DESIGNATIONS [...] Chapter 22.12 RESIDENTIAL DISTRICTS (R AND RR)”
  • Minimum dwelling sizeSpecified

    ADUs and JADUs inside Martinez city limits under Chapter 22.43.

    • This quoted minimum applies to ADUs/JADUs, not necessarily to every primary dwelling.
    • The alternative standard is the size necessary to accommodate an efficiency unit, whichever is greater.

    minimum ADU/JADU floor area: >= 150 square feet (or the size necessary to accommodate an efficiency unit, whichever is greater)

    “Minimum Size. An ADU/JADU shall be a minimum of 150 square feet or the size necessary to accommodate an efficiency unit as defined by Cal. Health & Safety Code § 17958.1, whichever is greater.”
  • Minimum lot sizeSpecified

    R-1.5 Residential District inside Martinez city limits.

    • The table note states that existing R-3.5 and R-2.5 sites below the required minimum are handled under § 22.12.120; that note does not expressly create the same exception for R-1.5.

    minimum site area: >= 5000 square feet

    “R-1.5* 5,000 square feet R-2.5 3,500 square feet R-3.5 4,000 square feet”
    One more reviewed finding on this topic
  • Lot coverageSpecified

    Newly constructed ADUs inside Martinez city limits.

    • The exemption applies to newly constructed ADUs and concerns the maximum lot coverage or floor-area-ratio otherwise allowed in the zoning or overlay district.
    “Lot Coverage and Floor Area Ratio. Newly constructed ADUs shall be exempt from the maximum lot coverage or floor area ratio allowed in the zoning or overlay district.”
  • Subdividing landRegulated (with conditions)

    Subdivision maps and land division inside Martinez city limits.

    • Subdivision maps must conform to the City's General Plan, precise plans and official plan lines, and Title 22 zoning provisions.
    • The zoning-conformity rule expressly covers land use, lot size and dimensions, parking and loading areas, and other applicable regulations.
    “A subdivision map shall conform with the zoning provisions of the City, as found in Title 22 of this code, hereinafter simply referred to as the zoning provisions, with respect to use of land, lot size and dimensions, space for off-street parking and off-street loading areas and other applicable regulations.”
  • Driveway accessRequired

    Development involving driveways inside Martinez city limits.

    • The requirement is part of the site-development permit process for plan checking and inspection of non-building site improvements.
    • An encroachment permit remains required for improvements within public rights-of-way.
    “A site development permit shall be required for each single parcel residential and non-residential development for the plan checking and inspection of all non-building site improvements including grading, drainage, streets, driveways, parking lots, walkways, and other related improvements.”
  • Permit feesVariable (with conditions)

    Work regulated by Martinez Municipal Code Chapter 15.04.

    • Permit fees are set from time to time by City Council resolution; the opened code section does not state a fixed fee amount.
    “Permit fees for work regulated by this Chapter shall be as adopted from time to time by resolution of the City Council of the City of Martinez.”
  • Permit processPartial

    Single-parcel residential and nonresidential development inside Martinez city limits.

    • A site development permit is required for plan checking and inspection of non-building site improvements.
    • An encroachment permit is still required for improvements within public rights-of-way.
    • The section does not provide the complete building-permit application process.
    “A site development permit shall be required for each single parcel residential and non-residential development for the plan checking and inspection of all non-building site improvements including grading, drainage, streets, driveways, parking lots, walkways, and other related improvements. The site development permit shall serve as a grading permit and permit for all other non-building on-site improvements. An encroachment permit for improvements within the public rights-of-way is still required.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Martinez or Contra Costa County directly.

  • Building permit — Building permits for construction inside Martinez city limits.
  • Owner-builder exemption — Owner-builders performing construction inside Martinez city limits.
  • Certificate of occupancy — Certificates of occupancy inside Martinez city limits.
  • Building height — Primary residential buildings inside Martinez city limits.
  • Living in an RV — Long-term recreational-vehicle occupancy on private land inside Martinez city limits.
11 more unanswered
  • Camping on your land
  • Tiny homes
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • 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 Martinez publishes no rule on the point, not that none exists. Contra Costa County’s page lists the county offices to call.

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