Bolthole Index

Solano County, California

Building permits, zoning and septic rules in Fairfield, California

Fairfield, California requires building permits for regulated construction, with applications handled by the city’s Building Safety Division.12 Fairfield administers its own zoning, while Solano County Environmental Health handles septic review for septic-dependent properties inside the city.34 Before planning an RV stay or tiny home, ask Fairfield Planning to confirm the proposed residential use; we could not confirm a general city rule allowing either on private land.5

At a glance

Building permits
Required for regulated construction; apply through Fairfield Building Safety12
Zoning
Fairfield has its own zoning ordinance and Planning Division35
Septic permits
Solano County Environmental Health reviews septic-dependent projects4
Minimum lot area
RVL districts have district-specific minimums; RL:10 requires 10,000 square feet67
Tiny homes
California requires an approved structure classification and an approved location8
Owner-builder
A conditional contractor-licensing exemption; building permits still apply9
Wells
California requires local approval before well construction, modification or destruction10

Who to call

Building permits

Fairfield Building Safety Division

City building permit applications, construction review and inspections

707.428.7451

[email protected]

1000 Webster St, 2nd Floor Fairfield, CA 94533

Zoning

Fairfield Planning Division

City zoning, development applications and land-use questions

707.428.7461

[email protected]

1000 Webster Street Second Floor Fairfield, CA 94533

Septic permits

Solano County Environmental Health Division - Technical Services

Sewage disposal permit applications and septic program questions

707-784-1636

[email protected]

675 Texas Street, Suite 5500 Fairfield, CA 94533

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

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Do you need a building permit in Fairfield, CA?

Fairfield construction subject to California’s building code requires a building permit before work begins, and the city’s Building Safety Division reviews new construction, improvements and alterations inside Fairfield.12 Fairfield has adopted the 2025 California Building Standards Code with local amendments.11 Ask Building Safety which building, electrical, plumbing or mechanical approvals your exact project needs before ordering materials.2

California’s owner-builder exemption concerns contractor licensing and does not waive building permits.9 Owners using the personal-work pathway must meet its conditions, including that improvements are not intended or offered for sale and that employees receive wages as their sole compensation.9

Who issues Fairfield building permits, and where do you apply?

Fairfield Building Safety is the city office for construction review; contact the division at 707.428.7451 or [email protected].2 The city directs applicants to create an account in BUILD and attach plans and supporting documentation, with PDFs that are not secured or password protected.2

Fairfield Planning administers zoning and processes development applications; contact Planning at 707.428.7461 or [email protected] for land-use questions.5 Start with Planning when the proposed use or development layout is uncertain, then ask Building Safety for the construction application requirements.52 Septic review stays with Solano County Environmental Health for septic-dependent Fairfield projects.4

Does Fairfield have zoning, minimum lot sizes and home-size rules?

Fairfield has a city zoning ordinance, so the parcel’s district matters when planning a home or dividing land.312 Minimum lot areas in RVL:40, RVL:20 and RVL:15 are 40,000, 20,000 and 15,000 square feet respectively; RL:10 has a 10,000-square-foot minimum.67 Fairfield’s residential table identifies a 960-square-foot dwelling-unit size requirement for RVL:40, RVL:20, RVL:15 and RL:10.13

Ask Fairfield Planning to identify the parcel’s zoning and applicable development standards before treating a small home or a lot split as feasible.5 Fairfield regulates subdivisions separately, so meeting a lot-area minimum does not by itself establish subdivision approval.12

How do septic permits work inside Fairfield?

Solano County Environmental Health reviews septic-dependent construction and septic repair or replacement serving Fairfield property; the review may require percolation results, a site evaluation, a complete application, fees and well-flow or potability testing.4 The county’s sewage disposal program requires a permit for installation, modification, repair and abandonment of onsite sewage disposal systems.14 A complete sewage disposal permit application and fee must reach Environmental Health for review and approval before work begins.14

Contact Environmental Health Technical Services at 707-784-1636 or [email protected] about the sewage disposal application.14 We could not confirm a general Fairfield sewer-connection mandate or the full septic inspection requirements; ask city Planning about utility service and Environmental Health about the proposed septic project.514

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

California says RVs are not intended as permanent dwellings and generally limits RV occupancy to mobilehome or special occupancy parks unless a local ordinance allows otherwise.15 We could not confirm Fairfield’s general private-land RV occupancy or temporary camping rule; ask Fairfield Planning about the proposed address, duration and use before relying on an RV while building.5

California requires a tiny home to meet an approved structure classification and have a location approved for that classification.8 Fairfield also requires city approval before a structure is used or occupied.16 For an ADU or JADU in Fairfield, rentals must be residential and last at least 30 consecutive days; that rule does not establish permission to live in an RV or settle every tiny-home proposal.17

Building a home in Fairfield: what are the steps?

  1. Ask Fairfield Planning to confirm zoning, the proposed residential use and the development review needed for the parcel.5
  2. Resolve wastewater design before construction: for a septic-dependent Fairfield project, ask Solano County Environmental Health what site evaluation, application and testing are required.4
  3. Create a BUILD account and submit the building permit application with plans and supporting documents as directed by Fairfield Building Safety.2
  4. Obtain the required building permit before starting regulated construction.1
  5. Complete the city’s occupancy approval requirements before moving in; Fairfield’s certificate requires compliance with city requirements and applicable agency approvals.16

What stays with Solano County, and what should Fairfield buyers check?

Solano County Environmental Health has jurisdiction inside Fairfield, including review of septic-dependent projects; Fairfield’s own offices administer city zoning and building applications.18452 For land outside city limits, consult the Solano County guide for the county’s unincorporated-area building and zoning requirements.1920

California requires local well permits before construction, modification or destruction; we could not confirm the precise Fairfield domestic-well procedure, so ask Environmental Health Technical Services to identify the correct application route.1014 Ask Fairfield Planning about sewer availability and the proposed off-grid sanitation arrangement before buying a parcel on the assumption that utility connections can be avoided.5

Watch-outs

  • Fairfield’s owner-builder pathway does not remove the building-permit requirement.9
  • Fairfield prohibits use or occupancy of a structure without the required city approval, even after construction is physically complete.16
  • We could not confirm general private-land RV, camping or off-grid sanitation permission in Fairfield; ask Fairfield Planning before committing to that use.5
  • Fairfield’s ADU and JADU rental rule requires at least 30 consecutive days and does not establish the rule for renting a primary dwelling.17

Sources

  1. Do I need a building permit for my project? (California statewide rule), quoted and re-checked
  2. Fairfield Building Safety Division (fairfield.ca.gov)
  3. City of Fairfield, CA Code of Ordinances (Fairfield), quoted and re-checked
  4. Solano County Permit Process (Fairfield), quoted and re-checked
  5. Fairfield Planning Division (fairfield.ca.gov)
  6. Section 25.20 Residential Zoning Districts (Fairfield), quoted and re-checked
  7. Section 25.20 Residential Zoning Districts (Fairfield), quoted and re-checked
  8. Information Bulletin 2016-01: Tiny Homes (California statewide rule), quoted and re-checked
  9. California Business and Professions Code Section 7044 (California statewide rule), quoted and re-checked
  10. Well Standards (California statewide rule), quoted and re-checked
  11. Chapter 5.2 Codes Adopted and Amended (Fairfield), quoted and re-checked
  12. Article III Subdivision Rules and Regulations (Fairfield), quoted and re-checked
  13. Section 25.20 Residential Zoning Districts (Fairfield), quoted and re-checked
  14. Solano County Environmental Health Division - Technical Services (solanocounty.gov)
  15. hcd.ca.gov (California statewide rule), quoted and re-checked
  16. ecode360.com (Fairfield), quoted and re-checked
  17. Section 25.20 Residential Zoning Districts (Fairfield), quoted and re-checked
  18. Environmental Health, quoted and re-checked
  19. When is a Building Permit Required? (2026 county census)
  20. Planning Services (2026 county census)

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 Fairfield

Fairfield’s own rules

  • Building code adoptedAdopted

    Building work inside Fairfield city limits where the city is the enforcing authority or has delegated authority.

    • The city adopts the 2025 California Building Standards Codes and related California codes, subject to Fairfield amendments.
    • The adoption is under Ordinance No. 2025-10.

    building code edition: 2025 (subject to Fairfield amendments)

    “The purpose of this article is to adopt by reference the 2025 edition of the California Building Standards Code, Title 24 of the California Code of Regulations, subject to the definitions, clarifications, and amendments set forth in this chapter.”
  • Certificate of occupancyRequired

    Use or occupancy of structures inside Fairfield city limits.

    • Approval of all applicable agencies, the city fire department, and other city departments with permit conditions is required.
    • The certificate must be posted conspicuously, except in Group R-3 occupancies and associated accessory structures.
    “Such a certificate shall not be issued until compliance with all city requirements has been met. Occupying or using a structure without this approval shall constitute a violation of this code and will be deemed a safety hazard and or a public nuisance.”
  • Local zoningPresent

    Land inside Fairfield city limits.

    • Fairfield's code contains a Zoning Ordinance in Chapter 25, Article I.
    “This Section provides land use and development regulations applicable to the residential zoning districts established by Section 25.12.2 (Zoning Districts Established).”
  • Subdividing landRegulated (with conditions)

    Subdivision and parcel-map activity inside Fairfield city limits.

    • The code contains minor subdivision, major subdivision, tentative map, final map, development-standard, reversion-to-acreage, compliance, fee, vesting-tentative-map, disclosure, park-land-dedication, and merger divisions.
    • The source identifies Ordinance No. 75-8 as the subdivision rules and regulations ordinance.
    “This article consists of the subdivision rules and regulations ordinance (Ord. No. 75-8).”
  • Driveway accessLimited

    Driveway frontage associated with ADU development inside Fairfield city limits.

    • The standard applies to ADUs and may be modified for cul-de-sac lots, flag lots, or expanded corners with narrow frontage.

    maximum parcel frontage devoted to driveways: <= 40 percent (cul-de-sac, flag lot, or expanded corner with narrow frontage)

    “No more than 40 percent of the frontage of a parcel shall be devoted to driveways. This standard may be modified for lots in a cul-de-sac, flag lot, or at an expanded corner with narrow frontage”
  • Short-term rentalsLimited

    Short-term rental use of an ADU or JADU inside Fairfield city limits.

    • An ADU or JADU may be rented only for residential purposes and not for fewer than 30 consecutive days.
    • This claim does not establish the general short-term-rental rule for primary dwellings.

    minimum rental period for ADU or JADU: >= 30 consecutive days

    “An ADU or JADU may only be rented, leased, and/or occupied for residential purposes. If an ADU or JADU is rented, it shall not be rented for a period of less than 30 consecutive days.”

Rules another office applies inside Fairfield

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

  • Minimum dwelling sizeSpecified

    Single-family residential districts RVL:40, RVL:20, RVL:15, and RL:10 inside Fairfield city limits.

    • The table identifies a 960-square-foot dwelling-unit size requirement for these residential district regulations.
    • Residential occupancy must also meet the Uniform Housing Code space and occupancy standards.

    dwelling unit size: 960 square feet

    “Buildings Dwelling Unit Size (square feet) 960 Maximum Floor Area Ratio 0.5 0.5 0.5 0.5”
  • Minimum lot sizeSpecified

    RVL:40, RVL:20, and RVL:15 residential districts inside Fairfield city limits.

    • The table states that figures are minimums measured from property lines and in linear feet unless otherwise indicated.
    • Average-for-new-subdivision requirements are 15% above minimum lot area and apply only to subdivisions of 20 or more lots.

    minimum lot area RVL:40: 40000 square feet · minimum lot area RVL:20: 20000 square feet · minimum lot area RVL:15: 15000 square feet

    “Lot Area (square feet) Minimum 40,000 20,000 15,000 10,000 Average for new subdivision (15% above min. lot area) 40,000 23,000 17,250 11,500”
    One more reviewed finding on this topic
    • Specified — RL:10 residential district inside Fairfield city limits.
      “RL (Residential, Low Density) District. The RL zoning district is intended for areas of single family detached homes on minimum lot sizes of 8,000 and 10,000 square feet (RL:8, RL:10).”
  • Septic permitRequired

    Septic-dependent construction and septic repair or replacement serving property inside Fairfield city.

    • Environmental Health signoff may require percolation results, a site evaluation, a complete septic system permit application, payment of the application fee, and well-flow and potability testing.
    • The official permit-process page identifies sewer or septic repair or replacement as permit work.
    “Some examples of projects requiring permits are as follows: Decks Room Additions Swimming Pools Water Heater Replacement Heater/Air Conditioners (New and Replacements) Sewer or Septic Repair or Replacement”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Fairfield or Solano County directly.

  • Lot coverage — Residential lots inside Fairfield city limits.
  • Living in an RV — Long-term or residential RV occupancy on private land inside Fairfield city limits.
  • Camping on your land — Temporary camping on private land inside Fairfield city limits.
  • Tiny homes — Tiny-home occupancy inside Fairfield city limits.
  • Septic inspection — Septic systems inside Fairfield city limits.
5 more unanswered
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Permit fees

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 Fairfield publishes no rule on the point, not that none exists. Solano County’s page lists the county offices to call.

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