Bolthole Index

LaSalle County, Illinois

Building permits, zoning and land rules in Mendota, Illinois

Mendota, Illinois requires city building permits for construction and other regulated work, with specific exemptions.1 Mendota has municipal zoning; LaSalle County zoning applies outside incorporated areas.23 Buildings with plumbing intended for habitation or occupancy must connect to public water and sewer where available, and private wells are prohibited inside Mendota city limits.4 For private sewage proposals, ask the city and LaSalle County Health Department to confirm the approval route.56

At a glance

Building permits
City building permits required for regulated work; listed exemptions apply1
Zoning
Municipal zoning applies inside Mendota2
Water and sewer
Public connections required where available for buildings with plumbing intended for habitation or occupancy4
Private wells
Not allowed inside city limits4
Floodplain development
Development permit from the Building Inspector required before floodplain development7
Owner-builder
State plumbing provisions do not establish a general exemption from city building permits81

Who to call

Building permits

Mendota Building Department / City Clerk’s Office

Building applications, permit payment, inspection scheduling and referrals for city utility and zoning questions

815-539-7459

[email protected]

800 Washington St Mendota, IL 61342

Planning & zoning

Mendota Zoning Office

City zoning questions and zoning map

815-539-7459

[email protected]

800 Washington St Mendota, IL 61342

Septic permits

LaSalle County Health Department

Environmental Health referral for private sewage questions; confirm jurisdiction for a Mendota address

815-433-3366

717 E Etna Road Ottawa , IL 61350

Contact details are copied from each office’s official page and were checked against it on October 12, 2026.

Off-grid gear

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

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Do you need a building permit in Mendota, IL?

Mendota requires an application to the building official before construction, enlargement, alteration, repair, moving, demolition, occupancy changes or regulated electrical, gas, mechanical and plumbing work.1 Mendota’s listed exemptions include certain finish work and one-story detached tool sheds, storage sheds, playhouses and similar accessory structures up to 120 square feet.1 Ask the Building Department to classify your exact project before relying on an exemption.5 A principal-building permit cannot issue until the Water and Sewer Department certifies serviceability and required zoning and other agency approvals have been received.1

Who issues building permits in Mendota, and where do you apply?

Start with Mendota’s City Clerk’s Office for building application forms, then deliver the application there or email the application files to [email protected].5 The Building and Property Safety Director reviews completed application materials.5 After approval, the applicant obtains and pays for the building permit at the City Clerk’s Office.5 Mendota tells applicants at permit pickup whether inspections are required, and inspections are included in the permit fee.5 Use the city’s building counter for work inside Mendota; the county zoning rules address unincorporated land.13

Does Mendota have zoning, and can you live in an RV or tiny home?

Mendota has its own zoning regulations, and required zoning approvals must reach the Building Department before a building permit can issue.21 Ask the Mendota Zoning Office to identify the parcel’s district and the permitted residential use before buying land for an unconventional home.9 We could not confirm Mendota’s rules for RV occupancy, temporary camping, tiny homes, manufactured homes or accessory dwellings; ask the Zoning Office about the proposed use.9 We also could not confirm district-specific minimum lot sizes, dwelling sizes or setbacks; request the applicable district requirements from that office.9

How do septic permits and water connections work inside Mendota?

Mendota requires public water and sewer connections for buildings with installed plumbing intended for habitation or occupancy when those services are adjacent to or abut the property.4 Private water well supplies are prohibited within Mendota’s corporate limits.4 A water connection requires a permit issued to a licensed plumber, advance payment and notice before excavation.4 We could not confirm the local private-sewage approval route inside Mendota; ask the city and LaSalle County Health Department before planning septic.56 Illinois requires plan approval from the Department or applicable local authority before construction of a new private sewage disposal system.10

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

  1. Ask Mendota’s Zoning Office to identify the zoning district and review your intended residential use.9
  2. Obtain the required zoning approvals and Water and Sewer Department serviceability certification before the city issues a principal-building permit.1
  3. Submit the building application through the City Clerk’s Office for review by the Building and Property Safety Director.5
  4. Obtain and pay for the approved building permit at the City Clerk’s Office.5
  5. Arrange the inspections specified at permit pickup, and ask the Building Department what is required before occupancy; we could not confirm Mendota’s certificate-of-occupancy procedure.5

What should you check before buying land in Mendota or LaSalle County?

For land outside Mendota city limits, use the LaSalle County guide: county zoning applies to unincorporated areas.3 Inside Mendota, floodplain development requires a development permit from the Building Inspector before work begins.7 Work in Illinois waterways, floodplains and wetlands can also require state and federal authorizations.11 For an access driveway involving a state-maintained roadway’s right-of-way, obtain IDOT authorization before work begins.12 An owner-built home still falls under Mendota’s building-permit requirements; Illinois’s qualifying owner-occupant plumbing exemption does not establish a general construction exemption.18

Watch-outs

  • Mendota’s private-well prohibition and public utility connection requirements matter before designing an off-grid home.4
  • We could not confirm private-sewage administration inside Mendota; ask the city and LaSalle County Health Department to identify the required approvals for the address.56
  • We could not confirm RV or tiny-home occupancy permission inside Mendota; ask the Mendota Zoning Office before using a parcel that way.9

Sources

  1. Chapter 129, Article I: Scope; Applicability; Administration (Mendota), quoted and re-checked
  2. City of Mendota, IL Code of Ordinances (Mendota), quoted and re-checked
  3. Land Use Department, quoted and re-checked
  4. Chapter 318, Article I: Connections (Mendota), quoted and re-checked
  5. Mendota Building Department / City Clerk’s Office (mendota.il.us)
  6. LaSalle County Health Department (lasallecountyil.gov)
  7. ecode360.com (Mendota), quoted and re-checked
  8. HB5913 Enrolled — Illinois Plumbing License Law amendment (Illinois statewide rule), quoted and re-checked
  9. Mendota Zoning Office (mendota.il.us)
  10. 77 Ill. Adm. Code 905.190 Installation Approval (Illinois statewide rule), quoted and re-checked
  11. Permit Application and Instructions (Illinois statewide rule), quoted and re-checked
  12. Highway Permits (Illinois statewide rule), 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.

Answers from the rulebook for Mendota

Mendota’s own rules

  • Building permitRequired

    Construction, enlargement, alteration, repair, moving, demolition, occupancy changes, and regulated electrical, gas, mechanical, or plumbing work inside Mendota city limits.

    • Permit exemptions include listed finish work, unchanged-size windows and doors, fences not over four feet, one-story detached accessory structures up to 120 square feet, and other specifically listed work.
    • No principal-building permit issues until the Water and Sewer Department certifies serviceability.
    • Required zoning and other agency approvals must be received first.

    accessory structure exemption floor area: <= 120 square feet (one-story detached accessory structures used as tool and storage sheds, playhouses and similar uses)

    “Required. Any owner or owner's authorized agent who intends to construct, enlarge, alter, repair, move, demolish or change the occupancy of a building or structure, or to erect, install, enlarge, alter, repair, remove, convert or replace any electrical, gas, mechanical or plumbing system, the installation of which is regulated by this chapter or adopted codes, or to cause any such work to be performed, shall first make application to the building official and obtain the required permit.”
  • Local zoningPresent

    Land inside Mendota city limits; the municipal code contains Chapter 340, Zoning.

    “Consistent with the City's zoning regulations, set forth in Chapter 340 of this Code, the legal use and occupancy of any building or structure existing on the date of adoption of this chapter or for which building permits have been applied and which meet all provisions of previous regulations may be continued without change, except as may be specifically covered in this chapter or as may be deemed necessary by the building official, or their authorized agent, for the general safety and welfare of the occupants and the public.”
  • Mandatory utility hookupWater and sewer (with conditions)

    Every building inside Mendota city limits with installed plumbing intended for human habitation or occupancy when public water and sewer service is adjacent to or abuts the property.

    • The code also states that no private water well supply is allowed within the corporate city limits.
    • A water connection permit issued to a licensed plumber and advance payment are required.
    • The service-installation notice must be given at least two days before excavation.

    advance excavation notice: >= 2 days

    “Use of public water and sewer required where available. Every building with an installed plumbing system and intended for human habitation or occupancy and located adjacent to or abutting property where there is a public water supply and sewer service shall have a connection to that public water supply and sewer system.”
  • Building in a floodplainRequired

    Reconstruction, rehabilitation, repair, alteration, additions, or other improvements to buildings or structures in flood hazard areas inside Mendota city limits.

    • The building official determines whether work constitutes substantial improvement or repair of substantial damage.
    • Where required, the adopted International Building Code and International Residential Code requirements apply.
    • Flood-hazard modifications require the specific findings and written notices stated in § 129-5(J).
    “No person, firm, corporation, or governmental body not exempted by law shall commence any development in the floodplain without first obtaining a development permit from the Building Inspector.”

Still unanswered

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

  • Owner-builder exemption — Owner-builders performing regulated construction inside Mendota city limits.
  • Certificate of occupancy — Certificates of occupancy for buildings inside Mendota city limits.
  • Minimum dwelling size — Minimum dwelling size requirements inside Mendota city limits.
  • Minimum lot size — Minimum lot sizes inside Mendota city limits.
  • Setbacks — Setbacks inside Mendota city limits.
17 more unanswered
  • Lot coverage
  • Building height
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Manufactured homes
  • Accessory dwellings
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Agricultural exemption
  • Subdividing land
  • Driveway access
  • Short-term rentals
  • 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 Mendota publishes no rule on the point, not that none exists. LaSalle County’s page lists the county offices to call.

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