Bolthole Index

Solano County, California

Building permits, zoning and land rules in Solano County, California

22Index Score / 100
#56 of 58 in California

Unincorporated Solano County, California requires building permits for most construction, with specific minor-work exemptions1. County zoning governs unincorporated land; inside Vallejo, the city handles building permits and zoning234. Solano County Environmental Health remains the onsite-sewage contact in Vallejo and surrounding unincorporated areas56.

At a glance

Building permit
Required for most construction in unincorporated Solano County1
Zoning
County zoning applies throughout the unincorporated area2
Septic
Environmental Health handles onsite sewage; septic repair or replacement requires a permit67
Owner-builder
Available under California's conditional owner-builder exemption8
RV living
Private-land occupancy was not confirmed; county-park stays are temporary only910
Tiny home
Allowed when approved under a recognized California structure or vehicle standard and local zoning11
Minimum home size
Room-area minimums apply, but they do not establish a total dwelling-size minimum12
Well
A local permit is required before construction, modification or destruction13

Who to call

Building permits

Solano County Resource Management - Building & Safety Services

Building permits and online applications

707-784-6765

building@solanocounty.gov

675 Texas St., Suite 5500, Fairfield, CA 94533

Online permits →

Zoning

Solano County Resource Management - Planning Services

Zoning lookups and development review

707-784-6765

planning@solanocounty.gov

675 Texas Street, Suite 5500, Fairfield, CA 94533

Online permits →

Septic permits

Solano County Environmental Health Division - Technical Services

Onsite sewage disposal program questions

707-784-1636

ehtechnical@solanocounty.gov

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 12, 2026.

Off-grid gear

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Do you need a building permit in Solano County, California?

Most construction in unincorporated Solano County requires a building permit1. A one-story detached shed, playhouse or similar structure no larger than 120 square feet can be exempt when it has no utilities1. Shade-cloth structures for nursery or agricultural use are exempt from the building permit, but service systems are excluded and need separate plumbing, electrical or mechanical permits1415. Plans must use the 2025 California codes, and each separate structure needs a separate application16. A licensed contractor, owner or certified agent may receive the permit1. Every permit issued by Solano County requires inspections, which the permit holder must schedule17.

Who issues Solano County building permits, and how do you apply?

Solano County Building & Safety Services handles building permits for unincorporated land118. Vallejo and Dixon handle their own building permits; onsite-sewage matters remain with Solano County Environmental Health3196. Call 707-784-6765, email building@solanocounty.gov or visit 675 Texas St., Suite 5500, Fairfield, CA 9453318. Apply through the online portal18. The published process is to determine requirements, register online, submit, complete plan review, pay fees and obtain inspections; details vary by permit type20. Plan-check fees are due at submittal and final permit fees at issuance16. Building, plumbing, electrical and mechanical permit fees vary with project valuation and square footage rather than a single flat price21.

Does Solano County have zoning?

Chapter 28 governs zoning in unincorporated Solano County; city property goes to the city's planning department222. City zoning applies in Vallejo, Fairfield, Vacaville, Benicia, Dixon and Rio Vista42324252627. Solano County Environmental Health remains the onsite-sewage authority in those cities6. Planning Services can identify the district at 707-784-6765 or planning@solanocounty.gov28. Allowed uses, setbacks and maximum building height depend on the zoning district and proposed development222930. The zoning district sets minimum parcel size; rural residential districts generally require at least 5 acres unless the property has public water and each new parcel has 50 feet of public-road frontage3132. Short-term rentals in unincorporated Solano County require the appropriate permit, a business license and transient-occupancy-tax registration before listing33. County room-area standards do not establish a confirmed minimum size for an entire dwelling34.

How do septic and well permits work in Solano County?

Solano County Environmental Health administers onsite-sewage permitting and inspection in Benicia, Dixon, Fairfield, Rio Vista, Suisun City, Vacaville, Vallejo and surrounding unincorporated areas6. Contact Technical Services at 707-784-1636 or ehtechnical@solanocounty.gov35. Septic repair or replacement is identified as work requiring a permit; before a related building permit can issue, Environmental Health may require percolation results, a site evaluation, a septic permit application and fee, and well tests7. We could not confirm a septic inspection schedule; ask Solano County Environmental Health Technical Services35. Only 3.3% of Solano County soils are rated “not limited” for conventional septic drain fields; a site evaluation is essential, and an engineered system may be needed36. Remodeled or new waterfowl hunting clubs in the Suisun Marsh within BCDC planning jurisdiction must use sewage holding tanks pumped by an approved service agent instead of septic systems37. A permit from the applicable local environmental health agency or water district is required before constructing, modifying or destroying a well13. For development projects, Environmental Health may require well-flow and water-potability tests before a building permit is issued; ask Technical Services which well requirements apply to the parcel3835.

Can you live in an RV, tiny home or ADU in Solano County?

We could not confirm a private-land RV occupancy rule for unincorporated Solano County, so ask Planning Services about the parcel28. Solano County parks cap camping at 14 days, require 30 days out and prohibit resident camping; these are park rules, not authorization to camp on private land910. Lake Solano campground prohibits arrivals after 9 pm, without exceptions10. A Solano County tiny home must be approved under a recognized California residential, building, manufactured-housing, factory-built-housing, recreational-vehicle, park-trailer or camping-cabin standard before occupancy; county zoning and development review still apply in unincorporated Solano County11. Manufactured homes require zoning approval and a building permit; septic, well, grading or temporary-use permits may also apply39. In unincorporated Solano County, ADUs and junior ADUs are allowed only on residential lots; similar housing on agricultural lots is classified as secondary dwellings under different criteria40.

What are the steps to build a home in Solano County?

  1. Confirm the parcel's jurisdiction, zoning, allowed use, setbacks and height limit with Planning Services412930.
  2. Establish septic and water feasibility with Environmental Health; septic repair or replacement requires a permit, and a well permit is required before construction, modification or destruction713.
  3. If the site is in a flood zone, have a registered surveyor or engineer prepare the required pre-construction elevation certificate42.
  4. Prepare separate code-compliant plans for each structure, apply online and complete plan review1620.
  5. Pay the valuation- and square-footage-based permit fees, then schedule every required inspection after work begins2117.
  6. Submit the post-construction elevation certificate before completion when the flood-zone rule applies42. California's owner-builder exemption can excuse a qualifying owner from contractor licensing, but it does not remove permit or inspection duties4317.

What should you check before buying land in Solano County?

Confirm jurisdiction, zoning, allowed use, setbacks, height limits224430. Subdividing unincorporated Solano County land for sale, lease or financing requires a tentative map and double the applicable zoning minimum parcel size; agricultural property under a Williamson Act contract must also meet that contract’s requirements4531. County subdivision rules also cover lot-line adjustments, mergers and reversions to acreage on land wholly or partly in the unincorporated area, subject to listed exemptions46. Agricultural leases are exempt from the subdivision chapter, not from zoning, building, septic or floodplain rules47. Determine whether the homesite is in a flood zone because new construction and substantial improvements there must elevate the lowest floor above base flood depth and require elevation certificates42.

Watch-outs

  • We could not confirm private-land RV occupancy or temporary-camping rules in unincorporated Solano County; ask Planning Services before relying on either during construction28.
  • Only 3.3% of Solano County soils are rated “not limited” for conventional septic drain fields; resolve site feasibility with Environmental Health before choosing a homesite3635.
  • Minimum parcel size, setbacks and building height vary by zoning district322930.
  • Flood-zone construction may require the lowest floor above base flood depth plus pre- and post-construction elevation certificates42.

Sources

  1. When is a Building Permit Required?, quoted and re-checked
  2. Planning Services, quoted and re-checked
  3. Vallejo: New Construction (Solano County), quoted and re-checked
  4. Vallejo: Vallejo Municipal Code § 16.202.02 — Development regulations, RR and RLD districts (Solano County), quoted and re-checked
  5. Vallejo: Environmental Health (Solano County), quoted and re-checked
  6. Environmental Health, quoted and re-checked
  7. Solano County - Permit Process, quoted and re-checked
  8. California Business and Professions Code Section 7044 (California statewide rule), quoted and re-checked
  9. Rules & Regulations, quoted and re-checked
  10. solanocounty.gov, quoted and re-checked
  11. Information Bulletin 2016-01 Tiny Homes, quoted and re-checked
  12. Room Additions, quoted and re-checked
  13. Wells, quoted and re-checked
  14. When is a Building Permit Required?, quoted and re-checked
  15. When is a Building Permit Required?, quoted and re-checked
  16. General Permitting Requirements, quoted and re-checked
  17. Inspections | Solano County, California, quoted and re-checked
  18. Solano County Resource Management - Building & Safety Services (solanocounty.gov)
  19. Dixon: official source (Solano County), quoted and re-checked
  20. About Building & Safety Services, quoted and re-checked
  21. Permit Process, quoted and re-checked
  22. Solano County - FAQs, quoted and re-checked
  23. Fairfield: City of Fairfield, CA Code of Ordinances (Solano County), quoted and re-checked
  24. Vacaville: City of Vacaville development conditions (Solano County), quoted and re-checked
  25. Benicia: Title 17 Zoning (Solano County), quoted and re-checked
  26. Dixon: Chapter 18.03: Zoning Districts and Zoning Map (Solano County), quoted and re-checked
  27. Rio Vista: Title 17 Zoning (Solano County), quoted and re-checked
  28. Solano County Resource Management - Planning Services (solanocounty.gov)
  29. solanocounty.gov, quoted and re-checked
  30. solanocounty.gov, quoted and re-checked
  31. Solano County Planning and Zoning FAQs, quoted and re-checked
  32. Solano County Planning FAQs, quoted and re-checked
  33. Short Term Rental, quoted and re-checked
  34. Room Additions, quoted and re-checked
  35. Solano County Environmental Health Division - Technical Services (solanocounty.gov)
  36. 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
  37. Suisun Marsh Protection Plan, quoted and re-checked
  38. Building & Safety Services FAQ, quoted and re-checked
  39. Mobile Modular Manufactured Homes, quoted and re-checked
  40. Accessory Dwelling Units (ADUs), quoted and re-checked
  41. Development Planning, quoted and re-checked
  42. Flood Zone Determination, quoted and re-checked
  43. California Business and Professions Code Section 7044, quoted and re-checked
  44. Room Additions, quoted and re-checked
  45. Solano County Planning FAQs, quoted and re-checked
  46. Chapter 26 Subdivisions, quoted and re-checked
  47. Chapter 26 Subdivisions, quoted and re-checked

Written October 12, 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.

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Compared with neighboring counties

Like all 6 of its neighbors, Solano County has countywide zoning.

RuleSolano CountyContra Costa CountyYolo CountyNapa CountySacramento CountyAlameda CountySan Joaquin County
Building permitRequiredRequiredRequiredLimitedRequiredRequiredRequired
County zoningYesYesYesYesYesYesYes
Septic permitsCounty Env. Health Div.Contra Costa HealthCounty Env. Health Div.County Env. Health Div.EMDCounty Dept. of Env. HealthCounty Env. Health Dept.

County locator

Solano County in California

22
County map
Solano County highlighted among the California counties · colored by Index score

How Solano County scores

Seclusion7100% ev.
Self-Sufficiency4096% ev.
Admin Boringness40100% ev.
Durability34100% ev.
Property Autonomy56100% ev.
Carry Cost45100% ev.

Evidence strength: 99%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →

$580kTypical home
0.7%Property tax
$12,901Land / acre
20.8"Annual rain
40.4% of yrsSevere drought
26.8 / yr (+15.2)Mid-century 100°F days
96.9 daysMid-century dry spell
1.57" (+6.6%)Mid-century 1-day rain
1.07×Wildfire change factor
100%Forward climate coverage
$1,364Home insurance / yr
5.8% / yrInsurance growth
0.71%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
426,899People within 30 min
12,240,589People within 2 hr
257,634Radius comparison (15 mi)
546.6People / sq mi
4%Federal land
78.2%Land at 15% slope or less
3.3%Soils rated "not limited" for septic (strict USDA rating)
13,411 acWorkable land screen
13.5%Wooded land
30.5 tonsBiomass / forest ac
61.3°FAvg temp

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Cities and towns in Solano County

Inside a city or town, that city usually issues building permits and sets zoning; the county’s rules above cover unincorporated land. Septic, wells and floodplain rules usually stay with the county or state everywhere.

Not yet researched: Suisun City

Answers from the rulebook for Solano County

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

Solano County rules

  • Building permitRequired

    Most construction in the Solano County Building & Safety Services jurisdiction, including construction in unincorporated Solano County.

    • A building permit is required unless the work is specifically exempted under CBC section 105.2.
    • Exemptions include one-story detached accessory structures used as tool or storage sheds, playhouses, or similar uses when no more than 120 square feet and without electrical, mechanical, or plumbing utilities.
    • Other listed exemptions include fences not over 6 feet high; oil derricks; retaining walls not over 4 feet measured from the bottom of the footing to the top of the wall unless supporting a surcharge or impounding Class I, II, or III-A liquids; grade-supported water tanks of no more than 5,000 gallons with height-to-diameter-or-width ratio no more than 2:1, although piping or electrical requires a permit; sidewalks and driveways no more than 30 inches above adjacent grade and not over a basement or story below and not part of an accessible route; painting, papering, tiling, carpeting, cabinets, countertops and similar finish work; temporary motion-picture, television and theater stage sets and scenery; certain above-ground prefabricated swimming pools less than 24 inches deep and no more than 5,000 gallons; nursery or agricultural shade-cloth structures excluding service systems; swings and playground equipment accessory to detached one- and two-family dwellings; certain wall-supported window awnings projecting no more than 54 inches; and nonfixed movable fixtures, cases, racks, counters and partitions no more than 5 feet 9 inches high.
    • Counters for commercial or industrial operations require permits.
    • If an emergency repair impacts safety, the permit application must be submitted within the following business day.
    • Permits may only be issued to a licensed contractor, the property owner, or the property owner's certified agent; contractor license and workers compensation insurance verification is required.

    detached accessory structure exemption floor area: <= 120 square feet (Must be one-story, detached, similar to a tool/storage shed or playhouse, and have no electrical, mechanical, or plumbing utilities.) · fence exemption height: <= 6 feet · retaining wall exemption height: <= 4 feet (Measured from bottom of footing to top of wall; no surcharge or Class I, II, or III-A liquid impoundment.) · water tank exemption capacity: <= 5000 gallons (Height-to-diameter-or-width ratio must not exceed 2:1; piping and electrical require permits.) · swimming pool exemption depth: < 24 inches (Must not exceed 5,000 gallons and must be entirely above ground; accessory to Group R-3 occupancy.) · window awning exemption projection: <= 54 inches (Must be supported by an exterior wall and not require additional support for Group R-3 or U occupancies.) · movable fixture exemption height: <= 5.75 feet (Commercial or industrial counters require permits.)

    “Building permits are required for most types of construction”
  • Building code adoptedAdopted (with conditions)

    Building plans submitted to Solano County Building & Safety Services under the county-administered building-permit process.

    • Plans must use the 2025 California Building Code based on the 2024 IBC.
    • Residential work uses the 2025 California Residential Code based on the 2024 IRC.
    • Mechanical, electrical, plumbing, fire, energy, green-building, wildland-urban-interface, and existing-building codes listed by the County are also the 2025 editions.
    • Each separate building or structure requires a separate building permit application.
    • Plan-check fees are due at submittal and final permit fees at permit issuance.

    building code edition: 2025 California Building Code (based on the 2024 IBC) · residential code edition: 2025 CRC (based on the 2024 IRC)

    “Plans shall be drawn using the 2025 California Building Code (based on the 2024 IBC)”
  • InspectionsRequired

    Construction performed under a building permit issued by Solano County Building & Safety Services.

    • All issued permits require building inspections.
    • Scheduling inspections is the responsibility of the permittee.
    • Requests received before 3:00pm are scheduled for the following business day; requests received after 3:00pm are scheduled 2 business days later.
    • The page states that not every inspection type applies to every job; the applicable inspection types must be requested through the county inspection line.
    “All issued permits require building inspections. Scheduling inspections is the responsibility of the permittee.”
  • County-wide zoningPresent (with conditions)

    County zoning regulations administered under Chapter 28 for property in unincorporated Solano County.

    • Chapter 28 is the Solano County zoning code.
    • The zoning ordinances apply to construction, alteration, moving, repair, and use of buildings, parcels of land, and signs.
    • Allowed uses and development standards vary by proposal and location.
    • The official county FAQ separately directs persons whose property is within a city to consult that city for city-specific matters.
    “The Solano County Code Compliance program has been empowered to investigate housing code violations, zoning code violations, and vehicle abatement issues.”
  • Local zoningVaries (with conditions)

    Aggregate conclusion for local zoning in Solano County: county zoning governs the unincorporated area, while incorporated city areas may be subject to city-specific zoning administration.

    • The County has adopted a General Plan and Zoning Ordinance.
    • Standards vary depending on the proposed use and location.
    • The zoning district determines whether a use is allowed and establishes applicable standards.
    • Some uses require a use permit.
    • A rezone requires a public hearing and County Board of Supervisors approval.
    • For property within city limits, the county FAQ states that the applicable city should be contacted for city matters.
    “County zoning regulations or General Plan policies are applicable in the unincorporated area only. [...] please contact the respective city’s planning department for planning inquiries.”
  • Zoning districtsPublished (with conditions)

    Zoning districts and parcel-level zoning information in unincorporated Solano County.

    • The county directs users to the Solano County GIS Parcel Viewer to look up General Plan land-use designations and zoning districts and view parcel zoning.
    • The county's Development Planning page states that county zoning regulations or General Plan policies apply to the unincorporated area.
    • Projects within city limits must be handled by the applicable city planning or zoning department.
    “This data displays the Zoning Districts of the unincorporated lands of Solano County, California.”
  • Minimum dwelling sizeSpecified

    Dwelling units covered by the County's room-addition guidance in the unincorporated area.

    • At least one habitable room in every dwelling unit must have at least 120 square feet of gross floor area.
    • Kitchens are excepted from the 120-square-foot requirement.
    • Other habitable rooms must have at least 70 square feet.
    • The cited page presents these as room-size requirements, not a total minimum floor area for the entire dwelling.

    minimum gross floor area for at least one habitable room: >= 120 sq ft (Kitchens) · minimum floor area for other habitable rooms: >= 70 sq ft (Kitchens)

    “Every dwelling unit shall have at least one habitable room that shall have not less than 120 square feet of gross floor area.”
    One more reviewed finding on this topic
    • Specified — Dwelling units in unincorporated Solano County, as addressed by the County room-addition building requirements.
      “one habitable room [...] not less than 120 square feet [...] Other habitable rooms [...] not less than 70 square feet.”
  • Minimum lot sizeDistrict specific (with conditions)

    Parcel-size requirements for properties in unincorporated Solano County zoning districts

    • The property’s zoning determines the minimum parcel size.
    • A subdivision generally requires double the minimum parcel size.
    • In rural residential zoning districts, the minimum parcel size is 5 acres unless the property is on public water and each parcel created has 50 feet of frontage on a public road.
    • Agricultural property in a Williamson Act contract must also comply with Williamson Act requirements.

    minimum parcel size in rural residential zoning districts: >= 5 acre (Unless the property is on public water and each parcel created has 50-feet of frontage on a public road.) · public-road frontage for each parcel created in rural residential zoning districts: >= 50 feet (Applies to the public-water exception.) · minimum parcel size for subdivision: double the applicable zoning minimum

    “For most zoning and planning inquiries about specific pieces of property in the unincorporated area of Solano County, the key piece of information we need is your Assessor Parcel Number (APN). [...] First, you must check the zoning for your property to determine your minimum parcel size. You must have double the minimum parcel site to subdivide. Please note in rural residential zoning districts you must meet the following conditions: minimum 5-acre parcel size unless you are on public water and each parcel to be created must have 50-feet of frontage on a public road.”
    One more reviewed finding on this topic
    • District specific (with conditions) — Subdivision and parcel-size requirements for property in unincorporated Solano County.
      “check the zoning [...] minimum parcel size. You must have double the minimum parcel site [...] minimum 5-acre parcel size unless [...] public water [...] 50-feet of frontage”
  • SetbacksDistrict specific (with conditions)

    Building, accessory-structure, and fence setbacks in unincorporated Solano County.

    • The applicable zoning district determines the minimum distances or setbacks.
    • A building permit application is routed to the Planning Division for zoning review.
    • Additional site-specific requirements may apply for easements and side, front, or rear yard areas.
    “Each property within the County is part of a designated zoning district. The zoning district specifies the permitted land uses, such as residential, commercial, or industrial and the minimum distances or set back from the property lines for buildings, accessory structures, and fences, as well as maximum height restrictions.”
    One more reviewed finding on this topic
    • District specific (with conditions) — Buildings, accessory structures, and fences on properties in unincorporated Solano County.
      “The zoning district specifies the permitted land uses, such as residential, commercial, or industrial and the minimum distances or set back from the property lines for buildings, accessory structures, and fences, as well as maximum height restrictions.”
  • Building heightDistrict specific (with conditions)

    Maximum building heights in unincorporated Solano County.

    • The applicable zoning district determines maximum height restrictions.
    • A building permit application is routed to the Planning Division for zoning review.
    • A variance may be available for additional height where the applicable zoning ordinance permits that process.
    “Each property within the County is part of a designated zoning district. The zoning district specifies the permitted land uses, such as residential, commercial, or industrial and the minimum distances or set back from the property lines for buildings, accessory structures, and fences, as well as maximum height restrictions.”
  • Living in an RVLimited

    Recreational-vehicle occupancy at Solano County parks and campgrounds.

    • A limit of 14 days applies with a mandatory 30-day out period.
    • Resident camping is prohibited.
    • Campers must place a recreational vehicle, tent, or trailer at the site to prove occupancy.
    • The source is a county-parks rule and does not establish a countywide rule for private land outside county parks.

    maximum stay: 14 days · mandatory out period: 30 days

    “A limit of 14 days with a mandatory 30-day out period enforced. No resident camping.”
  • Camping on your landLimited

    Temporary camping at Solano County parks and campgrounds.

    • A limit of 14 days applies with a mandatory 30-day out period.
    • Resident camping is prohibited.
    • No person under 18 may camp in a county park unless accompanied by a parent or legal guardian.
    • No camp arrivals are permitted after 9 pm at Lake Solano campground; the source states no exceptions.
    • Campers must place a recreational vehicle, tent, or trailer at the site to prove occupancy.

    maximum stay: 14 days · mandatory out period: 30 days · Lake Solano campground arrival cutoff: <= 9 pm (The source states no exceptions.)

    “No camp arrivals are permitted after 9 pm at Lake Solano campground. No exceptions.”
  • Manufactured homesLimited

    Placement and occupancy of manufactured homes in unincorporated Solano County.

    • A manufactured dwelling is designed for, or occupied exclusively by, one family.
    • It must be installed on a foundation system as a fixture or improvement to real property unless installed as a temporary dwelling or in a mobilehome park.
    • A temporary dwelling is limited to a fixed term and must serve a purpose specified by the applicable zoning district.
    • A building permit is required for temporary or permanent mobile/manufactured homes.
    • A temporary-use permit may be required for a temporary mobile/manufactured home.
    • Well/septic and grading permits may be required.
    • Planning Division zoning approval is required, and a Temporary or Conditional Use Permit may be required.
    • Manufactured homes proposed for installation must have been manufactured after February 1975, subject to the stated exception for certain older homes and required HCD certification.

    occupancy: one family · manufacture date: after February 1975 (The source provides an exception for specified older mobile homes or commercial coaches with written California-licensed architect or professional-engineer certification.) · permit validity: 2 years (The permittee has 180 days to commence work.)

    “A Building Permit is required for temporary or permanent mobile/manufactured homes.”
  • Accessory dwellingsLimited

    Attached and detached accessory dwelling units and junior accessory dwelling units on residential lots governed by Solano County.

    • ADUs and JADUs are allowed only on residential lots.
    • Agricultural lots are treated differently: similar housing is classified as secondary dwellings and must meet different criteria.
    • The Solano County Planning Division regulates attached and detached ADUs under Chapter 28 of the Solano County Code.
    • ADUs are subject to the California Residential Code and the Solano County Code.
    • Building permit fees depend on ADU size, location, and project valuation.
    • Public facilities fees are waived for ADUs 749 square feet or smaller and prorated for ADUs 750 square feet or larger based on primary dwelling size.
    • Fire sprinklers are required for all detached ADUs unless all listed conditions are met: the dwelling meets the ADU definition, the existing primary dwelling does not have automatic fire sprinklers, the detached ADU does not exceed 1,200 square feet, and the ADU is on the same parcel as the primary dwelling.
    • The county page states that building permit applications for ADUs must be submitted online.

    public facilities fee waiver threshold: <= 749 square feet (Public facilities fees are prorated for ADUs 750 square feet or larger based on primary dwelling size.) · public facilities fee proration threshold: >= 750 square feet (Proration is based on primary dwelling size.) · detached ADU sprinkler exemption size limit: <= 1200 square feet (All other listed exemption conditions must also be met.)

    “ADUs and JADUs are allowed only on residential lots.”
  • Who permits septicCounty

    Onsite sewage disposal permitting and inspection within Solano County cities identified by the county and surrounding unincorporated areas.

    • The county page states that Environmental Health has jurisdiction in Benicia, Dixon, Fairfield, Rio Vista, Suisun City, Vacaville, Vallejo, and surrounding unincorporated areas.
    • The page describes Environmental Health jurisdiction generally; it does not itself provide the detailed septic-specific allocation of authority.
    “EH has jurisdiction in the cities of Benicia, Dixon, Fairfield, Rio Vista, Suisun City, Vacaville, Vallejo, and surrounding unincorporated areas to issue permits, inspect facilities, investigate complaints, perform enforcement as necessary, and assists both the business community and the public.”
    One more reviewed finding on this topic
    • County — Onsite sewage disposal permitting and inspection by Solano County Environmental Health in the incorporated cities listed by the county and surrounding unincorporated areas.
      “EH has jurisdiction in the cities of Benicia, Dixon, Fairfield, Rio Vista, Suisun City, Vacaville, Vallejo, and surrounding unincorporated areas to issue permits, inspect facilities”
  • Septic permitLimited

    Sewer or septic repair or replacement projects subject to the Solano County Building & Safety Division permit process.

    • The source describes sewer or septic repair or replacement as an example of a project requiring a permit; it does not establish that every septic-related activity requires a permit.
    • Before a building permit can be issued, Environmental Health may require percolation test results, a site evaluation, a complete septic system permit application on file, payment of the appropriate septic system permit application fee, and well flow and water potability testing.
    • The source directs applicants to contact Environmental Health if they are unsure whether these conditions apply.
    “Some examples of projects requiring permits are as follows: Sewer or Septic Repair or Replacement”
  • Off-grid sanitationLimited

    Remodeled or newly constructed waterfowl hunting clubs in the Suisun Marsh portion of Solano County within the BCDC planning jurisdiction.

    • Sewage holding tanks are required instead of septic systems for remodeled and newly constructed waterfowl hunting clubs.
    • Tanks must be pumped out by an approved service agent.
    • The rule is described as administered by the Solano County Department of Resource Management.
    “install sewage holding tanks only and to have the tanks pumped out by an approved service agent.”
  • Well permitRequired

    Water-well construction, modification, or destruction in Solano County.

    • A permit must be obtained from the applicable local environmental health agency or local water district before construction, modification, or destruction.
    • Water-well construction must be performed by a licensed C-57 Well Drilling Contractor.
    • Applicable local and state well standards apply.
    • Local enforcing agencies may inspect wells during and after construction, modification, or destruction.
    • Public-supply wells have additional State Water Resources Control Board Division of Drinking Water requirements.
    “Well owners need to obtain permits from local environmental health agencies or local water districts before construction, modification, or destruction takes place.”
    One more reviewed finding on this topic
    • Limited — Water wells associated with development or construction projects in Solano County.
      “The following permits may also be applicable: [...] Env. Health: Well Permit Septic Tank Permit Other Agencies: Depending upon the location and type of structure, permits from other agencies may be required such as water/sewer districts, Air Quality Management Districts, etc.”
  • Agricultural exemptionConditional

    Building permit requirements for shade cloth structures constructed for nursery or agricultural purposes in Solano County.

    • The exemption applies to shade cloth structures constructed for nursery or agricultural purposes.
    • Service systems are excluded from the exemption.
    • Separate plumbing, electrical, and mechanical permits are required for otherwise exempted items.
    • The source frames the exemption under CBC section 105.2 permit exemptions.
    “A building permit is required unless it is specifically exempted in the following list (CBC section 105.2). These items do not require building permits: [...] 10. Shade cloth structures constructed for nursery or agricultural purposes, not including service systems.”
    2 more reviewed findings on this topic
    • Available — Mineral, oil, gas, or agricultural leases under the Solano County Subdivision Ordinance.
      “Mineral, oil, gas or agricultural leases;”
    • Available (with conditions) — Shade-cloth structures constructed for nursery or agricultural purposes in Solano County.
      “Shade cloth structures constructed for nursery or agricultural purposes, not including service systems.”
  • Subdividing landRegulated (with conditions)

    Subdivision of land in unincorporated Solano County

    • A tentative map is required whenever an owner wishes to subdivide property for sale, lease, or financing.
    • The General Plan, Subdivision Ordinance, and Zoning Ordinance govern subdivision design.
    • A map creating 4 or fewer new parcels is a Parcel Map; a map creating more than 4 new parcels is a Subdivision Map.
    • A tentative map must be finaled within two years or it expires.
    • Typical conditions may include rights-of-way, easements, and street improvements.
    • Williamson Act requirements also apply to agricultural property under contract.

    tentative-map finalization period: 2 years (The county FAQ states the tentative map must be finaled within two years or the map expires.) · parcel-map threshold: <= 4 new parcels

    “A Tentative Map is required whenever a property owner wishes to subdivide a property for sale, lease or financing. The General Plan, Subdivision Ordinance and Zoning Ordinance govern the design of the subdivision. The Tentative Map must be finaled within two years or the map expires. In order to final a map, the conditions of a map must be satisfied. A Map which creates 4 or fewer new parcels is a Parcel Map. A Map which creates more than 4 new parcels is a Subdivision Map.”
    One more reviewed finding on this topic
    • Regulated (with conditions) — Divisions, reversions to acreage, lot-line adjustments, and mergers involving real property wholly or partially within unincorporated Solano County.
      “all divisions, reversions to acreage, lot line adjustments, and mergers respecting real property located wholly or partially within the unincorporated areas of Solano County.”
  • Building in a floodplainRequired

    New construction and substantial improvements of structures in a flood zone under the Solano County Building Division's jurisdiction.

    • The requirement applies to construction in a flood zone.
    • The lowest floor, including the basement, must be elevated above base flood depth.
    • Elevation must comply with State and Federal requirements.
    • A pre-construction elevation certificate prepared by a registered land surveyor or engineer documents the planned elevation.
    • A post-construction elevation certificate must be submitted before project completion.
    • Detailed requirements are in Solano County Code Chapter 12.2.

    lowest floor elevation: above base flood depth (according to State and Federal requirements)

    “New construction and substantial improvements of any structure shall have the lowest floor, including the basement, elevated above base flood depth”
  • Short-term rentalsLimited

    Short-term rental facilities in the unincorporated areas of Solano County.

    • A short-term rental is temporary occupancy for 30 consecutive calendar days or less, including portions of calendar days as full days.
    • The occupant is any person other than the resident family.
    • The lodging right may be granted by money exchange, concession, permit, right of access, license, gift, or other agreement.
    • Time-share or co-ownership occupancy is included when limited to 30 consecutive days or less.
    • An occasional home exchange of a dwelling used as the property owner's primary residence is excluded.
    • Before listing, the operator must apply for the appropriate permit, obtain a Business License, and register for a Transient Occupancy Tax Certificate.

    maximum stay: <= 30 consecutive calendar days (portions of calendar days count as full days)

    “Stay is for a time period of 30 consecutive calendar days or less, includes portions of calendar days as full days.”
  • Permit feesVariable (with conditions)

    Building, plumbing, electrical, and mechanical permit fees administered by the Solano County Building & Safety Division.

    • Fees are charged for each type of permit.
    • The permit fee is based on project valuation and square footage.
    • Fees are calculated from fee tables established in the code.
    • The page does not provide specific fee amounts.

    fee basis: project valuation and square footage

    “The permit fee is based on the valuation and square footage of the project, and calculated from fee tables established in the code.”
  • Permit processPublished (with conditions)

    County building permit applications in unincorporated Solano County.

    • The general process is to determine project requirements, register in the online permit system and submit the application, have plans reviewed by the county, pay permit fees, and obtain required inspections after construction starts.
    • The page states that the process varies depending on the type of permit.
    “Although the process varies depending on the type of permit, these are the general steps to get started on your building permit:”

California rules that apply here

  • Owner-builder exemptionAvailable (with conditions)

    Exemption from California contractor-licensing chapter for an owner-builder who builds or improves a structure on the owner’s property; this does not itself establish exemption from local building permits, inspections, or other code requirements.

    • For work personally performed by the owner or performed by the owner’s employees, none of the improvements may be intended or offered for sale, and employee compensation must be wages as their sole compensation.
    • For work directly contracted to licensed trade contractors, the owner must directly contract with licensees duly licensed for the respective trades.
    • For single-family residential structures under the licensed-contractor arrangement, no more than four structures may be intended or offered for sale in a calendar year; this limitation does not apply if the owner contracts with a general contractor for construction.
    • For a homeowner improving a principal residence or its appurtenances, the work must be performed before sale, the homeowner must have actually resided in the residence for the 12 months before completion, and the homeowner must not have used this exemption on more than two structures more than once during any three-year period.
    • A nonprofit corporation may qualify when assisting an owner-builder participating in a mutual self-help housing program.
    • Sale or offering for sale within one year after completion creates a rebuttable presumption that the structure was undertaken for sale; sale or offering for sale of five or more structures within one year creates a conclusive presumption.
    • This is a contractor-licensing exemption and should not be treated as a building-permit exemption.

    single-family structures intended or offered for sale: <= 4 structures per calendar year (Does not apply if the owner contracts with a general contractor for construction.) · prior residence occupancy: >= 12 months before completion (Applies to the principal-residence homeowner exemption.) · owner-builder exemption use: <= 2 structures during any three-year period (The statute states the homeowner has not availed himself or herself of the exemption on more than two structures more than once during any three-year period.) · sale presumption period: 1 year after completion (Sale or offering for sale creates a rebuttable presumption; five or more structures creates a conclusive presumption.) · conclusive-presumption threshold: >= 5 structures within one year after completion (Structures sold or offered for sale by the owner-builder.)

    “This chapter does not apply to any of the following: (1) An owner who builds or improves a structure on his or her property”
    3 more reviewed findings on this topic
    • Available (with conditions) — Owners who build or improve a structure on their own California property, including qualifying principal-residence improvements; this is a California contractor-licensing exemption and does not eliminate applicable building-permit or inspection requirements.
      “(a) This chapter does not apply to any of the following: (1) An owner who builds or improves a structure on his or her property”
    • Conditional — Owners who build or improve structures on their own property, and homeowners improving their principal residence or appurtenances, subject to Business and Professions Code section 7044.
      “(a) This chapter does not apply to any of the following: (1) An owner who builds or improves a structure on his or her property”
    • Available (with conditions) — California contractor-licensing requirements for an owner who builds or improves a structure on the owner’s property; this is not stated as an exemption from building permits, inspections, or other code requirements.
      “This chapter does not apply to any of the following: (1) An owner who builds or improves a structure on his or her property”
  • Certificate of occupancyRequired

    Completed construction projects within HCAI jurisdiction involving California health facilities.

    • The HCAI Compliance Officer issues the project-completion Substantial Compliance or Certificate of Occupancy once required conditions are met.
    • The stated examples include delivery of all test reports to the Inspector of Record, clearance of outstanding items, and completion of the Testing, Inspection and Observation Program.
    • Once construction is completed, the certificate of occupancy allows the owner to apply to the Department of Health Services for a license to operate the health facility.
    “Issues the certificate of occupancy and/or construction final.”
  • Tiny homesAllowed (with conditions)

    Occupancy of a structure marketed or described as a tiny home in California.

    • The tiny home must comply with applicable standards and be approved as a HUD-Code manufactured home, California Residential or Building Code home, factory-built housing, recreational vehicle, park trailer, or camping cabin.
    • The location must be approved for the applicable classification.
    • A tiny home that does not fit one of those classifications and does not comply with the California Building Standards Code is a noncomplying structure whose occupancy is illegal.
    • Approving and enforcing agencies vary depending on whether the unit is inside or outside a mobilehome or special occupancy park.

    park trailer or RV gross area limit: <= 400 square feet (Applicable classification-specific exclusions and standards apply.)

    “In order to be occupied, a tiny home must comply with the standards of, and be approved as one of the following types of structures: a HUD-Code manufactured home (MH), California Residential Code or California Building Code home, factory-built housing (FBH), recreational vehicle (RV), park trailer (PT) or camping cabin (CC).”
    One more reviewed finding on this topic
    • Allowed (with conditions) — Occupancy of a tiny home in Solano County, including the unincorporated area, when the structure is approved under an applicable California residential, building, manufactured-housing, recreational-vehicle, park-trailer, factory-built-housing, or camping-cabin standard.
      “In order to be occupied, a tiny home must comply with the standards of, and be approved as one of the following types of structures:”
  • Septic inspectionLimited

    OWTS in a Tier 3 Advanced Protection Management Program with supplemental treatment components, including systems in specified impaired-water-body areas statewide.

    • The requirement applies to OWTS in an Advanced Protection Management Program with supplemental treatment components.
    • Ongoing monitoring must follow the OWTS operation and maintenance manual or occur more frequently if required by the local agency or Regional Water Board.
    • Where telemetry is not possible, the owner or owner's agent must inspect at least monthly while the system is in use and notify the service provider at least quarterly of observed operating parameters.
    • For systems designed to meet disinfection requirements, a service provider must inspect proper operation quarterly while the system is in use unless continuous telemetric monitoring is capable of assessing operation.
    • Quarterly effluent sampling and certified-laboratory requirements apply to systems subject to the disinfection provisions.

    inspection frequency where telemetry is not possible: per monthly (While the system is in use.) · inspection frequency for disinfection systems: per quarterly (While the system is in use, unless continuous telemetric monitoring is capable of assessing operation.)

    “Where telemetry is not possible, the owner or owner’s agent shall inspect the system at least monthly while the system is in use as directed and instructed by a service provider and notify the service provider not less than quarterly of the observed operating parameters of the OWTS. [...] OWTS in an Advanced Protection Management Program designed to meet the disinfection requirements in Section 10.10 shall be inspected for proper operation quarterly while the system is in use by a service provider unless a telemetric monitoring system is capable of continuously assessing the operation of the disinfection system.”
  • Mandatory utility hookupSewer (with conditions)

    Certain existing OWTS in California Tier 3 impaired-water-body areas that commit to connect to a centralized wastewater collection and treatment system regulated through waste discharge requirements.

    • The OWTS must have been constructed and operating, or permitted, on or before the date the nearby water body was added to OWTS Policy Attachment 2.
    • The owner must commit by legally binding document to connect to a centralized wastewater collection and treatment system regulated through waste discharge requirements.
    • The owner must sign the legally binding document within 48 months after the nearby water body's initial listing on Attachment 2.
    • The specified connection date may not extend beyond nine years after the date the nearby water body is added to Attachment 2.
    • The rule is an exception to Section 10 requirements for qualifying existing or permitted systems; it is not a general statewide requirement that every property connect to public sewer.

    deadline to sign connection commitment: 48 months (Measured from the date the nearby water body is initially listed on Attachment 2.) · maximum time to complete connection: <= 9 years (Measured from the date the nearby water body is added to Attachment 2.)

    “The owner must sign the document within forty-eight months of the date that the nearby water body is initially listed on Attachment 2. The specified date for the connection to the centralized community wastewater collection and treatment system shall not extend beyond nine years following the date that the nearby water body is added to Attachment 2.”
  • Driveway accessRequired

    Driveways and driveway connections involving proposed encroachments within, under, or over State highway rights of way.

    • The requirement applies to proposed activities related to placement of encroachments within, under, or over State highway rights of way.
    • Applications are submitted to the appropriate District Encroachment Permits Office having jurisdictional authority over the site.
    • Local or other agency requirements may also apply outside State highway rights of way.
    “An encroachment permit must be obtained for all proposed activities related to the placement of encroachments within, under, or over the State highway rights of way.”
  • Campground & park staysLimited

    Occupancy and use of manufactured homes and mobilehomes in California mobilehome parks and other locations subject to HCD jurisdiction.

    • HCD administers titling and registration for manufactured homes and mobilehomes.
    • HCD-inspected mobilehome parks are subject to health and safety enforcement where local government has not assumed enforcement.
    • Manufactured/mobilehome park regulations address construction, use, maintenance, and occupancy.
    • Separate local land-use, building, fire, health, and utility requirements may apply.
    “MHs may be occupied outside or inside of mobilehome parks and installation and approval for occupancy is governed by the Mobilehome Parks Act (MPA), HSC Sections 18200, et seq., and Title 25, CCR Sections 1000, et seq.”
    One more reviewed finding on this topic
    • Limited — Occupancy and use of recreational vehicles in California special occupancy parks and designated RV sections of mobilehome parks.
      “Unless otherwise allowed by a local ordinance, RVs generally may be occupied only in mobilehome parks or special occupancy parks governed by the Mobilehome Parks Act”
  • county zoning authorityGeneral

    California county legislative bodies' authority to adopt zoning ordinances regulating buildings, structures, land uses, lots, yards, open space, lot coverage, intensity of use, parking, loading, and setbacks within county jurisdiction, including unincorporated areas.

    • The authority is exercised pursuant to Government Code Chapter 4, Zoning Regulations.
    • The statute separately authorizes city legislative bodies; incorporated municipalities may exercise their own zoning authority.
    • Government Code Section 65850 also lists authority to regulate signs and billboards, building and structure location, height, bulk, number of stories, and size, lot and open-space size and use, lot coverage, intensity of land use, offstreet parking and loading, and building setback lines.
    • The cited section states it was amended by Stats. 2017, Ch. 376, Sec. 1, effective January 1, 2018.
    “The legislative body of any county or city may, pursuant to this chapter, adopt ordinances that do any of the following:”
  • county building authorityGeneral

    California counties administering and enforcing state building standards through county building departments, including residential construction in unincorporated areas.

    • Each county must maintain building standards and state building regulations in the office of the building official responsible for administration and enforcement of state building standards.
    • The statewide Title 24 standards apply subject to statutory exceptions and any authorized local amendments or local requirements.
    • The cited HCD bulletin concerns the 2019 California Building Standards Code and its July 1, 2021 supplement; later code editions may supersede those particular edition dates.
    “These codes shall be maintained in the office of the building official responsible for the administration and enforcement of state building standards”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

  • Lot coverage — Lot-coverage limits in unincorporated Solano County.

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.

Water rights & wells in Solano County

Whether a new home can legally get its own water here — the sub-state groundwater regime, from California’s water agency.

Actively managed

This basin is under active state management — new water use is scrutinized, though a domestic well is usually still allowed.

Household wellPermit required — restricted

California requires no STATE permit for a domestic well — wells are permitted by the county — but under SGMA a Groundwater Sustainability Agency can meter or restrict new wells in medium/high-priority and critically overdrafted basins, and Executive Order N-7-22 requires counties in those basins to get GSA verification that a new well is consistent with the Groundwater Sustainability Plan before permitting.

Limit: 2 acre-feet/year de minimis under SGMA (Water Code §10721(e)) — largely exempt from GSA metering/fees

California DWR / State Water Board — SGMA de minimis & EO N-7-22 Action 9 FAQ ↗
  • Sacramento Valley high-priority subbasinspartial of county

    High-priority SGMA subbasins (Corning, Colusa, Vina, Antelope-Tehama, South Yuba, North & South American, Solano, Yolo) with adopted GSPs; a new well is subject to GSA/EO N-7-22 consistency review.

    California DWR — SGMA Basin Prioritization ↗

Hybrid state (appropriation + riparian). Groundwater rules change and basin boundaries follow the aquifer, not the county line — confirm current well and appropriation rules with the California state water agency before you buy or drill.Groundwater governance as of Jul 2026, cited to each administering agency.

Living off-grid in Solano County, California

Is Solano County a good place to live off-grid or homestead?

Solano County scores 22/100 on the Bolthole Index, a weak county profile. Watch-outs: about 426,899 people within a 30-minute drive and elevated mid-century heat, water, rain, or wildfire exposure.

Do you need a building permit in Solano County, California?

Solano County generally requires a residential building permit, and it enforces county zoning. Onsite septic is permitted by Solano County Environmental Health Division (Onsite Sewage Disposal Program). Owner-builders may act as their own contractor to build their home. These answers are quoted from official sources and independently re-checked. Rules change and cities within the county differ — always confirm with the county before you buy or build.

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

Living in an RV on your own land in Solano County is allowed on a temporary basis only: Statewide rule. Occupancy of recreational vehicles as residential units in California. RVs are not intended for occupancy as permanent dwellings. Unless a local ordinance allows otherwise, RV occupancy generally is limited to mobilehome parks or special occupancy parks governed by the Mobilehome Parks Act or Special Occupancy Parks Act. A tiny home is allowed. Confirm with the county before relying on it.

How much does land cost in Solano County, California?

Land in Solano County runs about $12,901 per acre, based on the latest county data.

What is the water situation in Solano County?

Solano County gets about 20.8" of rain a year, with severe drought in roughly 40.4% of years. On water rights, Solano County lies in the Sacramento Valley high-priority subbasins — High-priority SGMA subbasins (Corning, Colusa, Vina, Antelope-Tehama, South Yuba, North & South American, Solano, Yolo) with adopted GSPs; a new well is subject to GSA/EO N-7-22 consistency review..

How remote is Solano County?

A representative private-land location has about 426,899 people within a 30-minute drive and 12,240,589 within two hours. The road-network catchments count population across county lines and clusters of smaller cities; straight-line radius values remain available as a comparison.

How Solano compares in California

Compare side-by-side →See all 58 California counties ranked →