Bolthole Index

LaSalle County, Illinois

Building permits, zoning and septic rules in Ottawa, Illinois

Ottawa, Illinois requires building permits for all new homes, issued through the city Building Department.1 Ottawa sets its own zoning inside city limits; the county zoning rules apply to unincorporated LaSalle County.23 Private sewage disposal inside Ottawa requires a permit signed by the city plumbing inspector, so contact the city before arranging a septic installation.4

At a glance

Building permits
City building permits required for all new homes and structural work1
Zoning
Ottawa zoning districts govern land inside city limits2
Septic permits
City plumbing inspector signs the private-disposal permit where public sewer is unavailable4
RV living
Floodplain protection applies to RVs installed longer than 180 days per year; general private-lot occupancy remains unconfirmed5
Residential lot size
A-1 interior lots: at least 9,600 square feet, with separate width and depth requirements6
Owner-builder
Conditional owner-occupant electrical permit exception; ask the city for full conditions7

Who to call

Building permits

Ottawa Building Department

City building permits, construction inspections, floodplain-development applications and routing to the plumbing inspector

815-433-0161 Ext. 230

301 West Madison Street Ottawa , IL 61350

Planning & zoning

Ottawa Community Development Department — Planning and Zoning

City zoning, land use and subdivision questions

815-433-0161 Ext. 242

301 W. Madison St. Ottawa , IL 61350

Health department

LaSalle County Health Department

County health contact for coordinating private sewage questions with Ottawa’s plumbing inspector

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 11, 2026.

Off-grid gear

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

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Do you need a building permit in Ottawa, IL?

Ottawa requires building permits for all new homes, structural work, room additions, basements, decks, and sheds or garages larger than 120 square feet.1 Ottawa has adopted the 2024 International Building Code and International Residential Code, with additional city requirements for residential construction.8

For a lot in an approved subdivision or replat, Ottawa cannot issue a building permit until the subdivision chapter’s requirements have been satisfied.9 Ask the Building Department to review the proposed work and subdivision status before setting a construction date.19

Who issues building permits and handles zoning in Ottawa?

Ottawa’s Building Department reviews plans, issues building permits and conducts construction inspections within the city.1 Call the Building Official at 815-433-0161 Ext. 230 for the application requirements for your project.1 Ottawa’s Community Development Department handles zoning, land use and development; the City Planner and Zoning Official administer municipal zoning and subdivision regulations.10

A building application must include a drawing locating the proposed building with dimensions from all lot lines.1 Ottawa generally takes 5 to 10 days to review a permit application, with longer review possible when changes are needed.1

Does Ottawa have zoning, lot-size rules and setbacks?

Ottawa has municipal zoning, including residence districts and a rural district with district-specific uses and dimensions.211 Ask Ottawa Community Development to identify the parcel’s district and applicable yards before choosing a house footprint.10

In Ottawa’s A-1 single-family residence district, interior lots must be at least 80 feet wide, 120 feet deep and 9,600 square feet in area.6 The A-1 corner-lot standards include a 10,000-square-foot minimum, subject to the provision for previously lawfully created lots.6 A-1 buildings and accessories cannot cover more than 40 percent of the lot.12 Lot area alone therefore does not establish the allowable building footprint: confirm the district’s yards with the city as well.1210

How do septic permits work inside Ottawa?

Where public sewer is unavailable, constructing a private sewage disposal system inside Ottawa requires a permit signed by the city plumbing inspector on city forms.4 Ottawa’s plumbing inspector may inspect during construction, and the applicant must request final inspection before covering underground portions.13

Ottawa requires qualifying properties abutting a street, alley or right-of-way with an available public sanitary sewer to connect at the owner’s expense within 120 days after official notice.14 An off-grid plan does not bypass sanitation rules: Ottawa prohibits privies, septic tanks and other disposal facilities except under its private-system provisions.15 Contact the city plumbing inspector first, then coordinate any county health requirements with LaSalle County Health Department, whose private sewage program requires installation and repair permits and inspections.161718

Can you live in an RV or tiny home in Ottawa?

Ottawa’s floodplain rules apply building-protection requirements to travel trailers and recreational vehicles installed on a site for more than 180 days per year.5 That floodplain provision does not establish permission to live in an RV on an ordinary private lot; ask Ottawa Community Development for the parcel’s permitted use and any temporary-occupancy approval.510

Ottawa permits camping areas among public recreational facilities in the POS park and open space district, a rule that does not authorize private-lot camping generally.19 We could not confirm Ottawa’s tiny-home occupancy rules or a general minimum dwelling floor area; ask the City Planner about the proposed use and the Building Official about the dwelling design.101

Building a home in Ottawa: what are the steps?

  1. Ask Ottawa Community Development to confirm the zoning district, permitted dwelling use and subdivision status for the address.10
  2. Submit the applicable site-development plans; Ottawa requires site-plan approval before issuing a building permit.1
  3. Establish sewer availability; if a private disposal system is needed, obtain the city plumbing-inspector permit and arrange the required inspection before underground work is covered.413
  4. Submit the building application with a drawing dimensioned from all lot lines, and arrange construction inspections through Ottawa’s Building Department.1
  5. Ask the city which utility-connection and street permits apply: water and sewer services need a connection permit, and work within the street right-of-way needs a street permit.1

What should you check before buying land in Ottawa?

Ask Ottawa’s Building and Zoning Official whether the proposed work is in a floodplain: the city requires a special flood hazard development permit and elevation certificate for proposed floodplain work.1 For an owner-built project, Ottawa has a conditional owner-occupant exception for electrical permits, but the full conditions need confirmation with the city.7

We could not confirm a private-well permit requirement or a general certificate-of-occupancy requirement inside Ottawa; ask the Building Official before finalizing a water supply or move-in date.1 Outside city limits, use the LaSalle County guide for the county’s building and zoning requirements, which govern unincorporated land.320

Watch-outs

  • Ottawa building permits expire if work has not started within 6 months, and the maximum permit length is 2 years.1
  • Ottawa’s floodplain RV duration rule does not establish a general right to occupy an RV on private land; ask Community Development about the proposed use.510
  • Private sewage systems inside Ottawa require the city plumbing inspector’s permit; do not treat a county septic application as the complete city approval.4

Sources

  1. Ottawa Building Department (cityofottawa.org)
  2. Chapter 118, Sec. 118-4: A residence districts (Ottawa), quoted and re-checked
  3. Land Use Department | LaSalle County, IL, quoted and re-checked
  4. Chapter 106, Sec. 106-331: Regulations for constructing (Ottawa), quoted and re-checked
  5. Chapter 74, Sec. 74-207: Protecting buildings (Ottawa), quoted and re-checked
  6. Chapter 118, Sec. 118-4: A residence districts (Ottawa), quoted and re-checked
  7. Chapter 22, Sec. 22-162.1: Application, issuance, transferability, and expiration of permit (Ottawa), quoted and re-checked
  8. Chapter 22, Sec. 22-125: Additional requirements (Ottawa), quoted and re-checked
  9. Chapter 90, Sec. 90-19: Building permit (Ottawa), quoted and re-checked
  10. Ottawa Community Development Department — Planning and Zoning (cityofottawa.org)
  11. Chapter 118, Sec. 118-4: A residence districts (Ottawa), quoted and re-checked
  12. Chapter 118, Sec. 118-4: A residence districts (Ottawa), quoted and re-checked
  13. library.municode.com (Ottawa), quoted and re-checked
  14. Chapter 106, Sec. 106-332: Sewer connection required (Ottawa), quoted and re-checked
  15. Chapter 106, Sec. 106-331: Regulations for constructing (Ottawa), quoted and re-checked
  16. library.municode.com (Ottawa), quoted and re-checked
  17. Sewage Disposal, quoted and re-checked
  18. LaSalle County Health Department (lasallecountyil.gov)
  19. Chapter 118, Sec. 118-11: POS park and open space district (Ottawa), quoted and re-checked
  20. LaSalle County Building Permit Ordinance, 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 Ottawa

Ottawa’s own rules

  • Building permitLimited

    Construction of a building, structure, or improvement on a lot within an Ottawa subdivision approved for platting or replatting.

    • No building permit may issue until all Chapter 90 subdivision requirements are satisfied.
    “No building permit shall be issued by any governing official for the construction of any building, structure or improvement to the land or any lot within a subdivision as defined herein, which has been approved for platting or replatting, until all requirements of this chapter have been fully complied with.”
  • Owner-builder exemptionConditional

    Electrical permits for an owner-occupant's dwelling or accessory structure inside Ottawa city limits.

    • The cited provision cross-references Section 22-161.8 for the owner-occupant exception; the full conditions of that cross-reference were not included in the opened excerpt.
    “No electrical permit will be issued to any person other than someone appropriately licensed under this article unless the permit is issued to the owner-occupant for his/her dwelling or accessory structure as provided in section 22-161.8.”
  • Building code adoptedAdopted (with conditions)

    Residential construction inside Ottawa city limits.

    • The city states that the 2024 International Building Code and 2024 International Residential Code are adopted; additional Ottawa-specific requirements also apply to all residential construction.
    “Notwithstanding the adoption of the 2024 International Building Code and the 2024 International Residential Code, or any provision of this article III to the contrary, the following building requirements and regulations shall apply to all residential construction:”
  • InspectionsLimited

    Work covered by the facade improvement program inside Ottawa city limits.

    • A city building permit must be obtained before construction; all work is inspected by the building official.
    “A building permit shall be obtained from the city prior to construction, and all work shall be inspected by the building official.”
  • Local zoningPresent

    Land inside Ottawa city limits.

    • Ottawa City Code Chapter 118 establishes municipal zoning districts and permitted uses.
    “"A-1" single-family residence district. The "A-1" single-family residence district is principally for detached single-family dwellings and related educational, religious and recreational facilities.”
  • Zoning districtsPublished

    Zoning districts inside Ottawa city limits.

    • Opened code sections identify A-1, A-2, B, R, and POS districts, with district-specific uses and dimensional standards.
    “The "R" Rural District is intended for agricultural uses and those single-family residential uses that are exempt by law from county or city subdivision ordinances.”
  • Minimum lot sizeSpecified

    Single-family dwellings in Ottawa's A-1 single-family residence district.

    • Interior lots must be at least 80 feet wide, 120 feet deep, and 9,600 square feet; corner lots must be at least 96 feet wide, 120 feet deep, and 10,000 square feet unless lawfully created before the chapter.

    interior lot width: >= 80 feet · interior lot depth: >= 120 feet · interior lot area: >= 9600 square feet · corner lot area: >= 10000 square feet (unless lawfully created before passage of the chapter)

    “No single-family home shall be erected on an interior lot less than 80 feet wide nor less than 120 feet deep nor less than 9,600 square feet in area. Corner lots less than 96 feet wide nor less than 120 feet deep nor less than 10,000 square feet in area shall be used for any dwelling unless such lot was lawfully created prior to the passage of this chapter.”
  • Lot coverageSpecified

    Buildings and accessories on lots in Ottawa's A-1 district.

    • Building coverage may not exceed 40 percent of the lot area.

    maximum building coverage: <= 40 percent of lot area

    “No building, with its accessories, shall occupy in excess of 40 percent of the area of any lot.”
  • Building heightSpecified

    Buildings in Ottawa's A-1 and A-2 residence districts.

    • Buildings may not exceed 35 feet or two and one-half stories.

    maximum height: <= 35 feet (or two and one-half stories)

    “No buildings shall exceed 35 feet or two and one-half stories in height.”
    One more reviewed finding on this topic
  • Living in an RVLimited

    Travel trailers and recreational vehicles installed on a site inside an Ottawa floodplain for more than 180 days per year.

    • Floodplain building-protection requirements apply; the cited section provides exceptions and additional elevation and anchoring requirements.

    site duration threshold: > 180 days per year

    “Installing a travel trailer or recreational vehicle on a site for more than 180 days per year.”
  • Camping on your landAllowed (with conditions)

    Camping areas operated as public recreational facilities in Ottawa's POS park and open space district.

    • The use is listed among permitted public recreational facilities in the POS district; the provision does not establish unrestricted private-lot camping.
    “Public recreational facilities including playgrounds, public swimming pools, playing fields, trails, sports activities, outdoor amphitheaters, camping areas, picnicking areas, shelters, field house, boating areas, fishing activities, golf courses and accessory uses such as related parking, washrooms, storage, and other similar uses.”
  • Who permits septicMixed (with conditions)

    Private sewage disposal inside Ottawa city limits.

    • The city plumbing inspector issues the city permit and may inspect; private systems must comply with state licensing and Illinois EPA requirements; availability is defined by the Illinois Department of Public Health Private Sewage Disposal Code.
    “Persons desiring to construct a private disposal system within the city must first obtain a permit signed by the plumbing inspector on forms furnished by the city.”
  • Septic permitRequired

    Construction of a private disposal system inside Ottawa city limits where public sewer is unavailable.

    • The permit must be signed by the city plumbing inspector; private systems must comply with state and Illinois EPA requirements.
    “Persons desiring to construct a private disposal system within the city must first obtain a permit signed by the plumbing inspector on forms furnished by the city.”
  • Septic inspectionRequired

    Private disposal systems constructed inside Ottawa city limits.

    • The plumbing inspector may inspect at any stage; the applicant must notify the inspector for final inspection before underground portions are covered.
    “The plumbing inspector will be allowed to inspect the work at any stage of construction, and the applicant must notify the plumbing inspector when the work is ready for final inspection and before any underground portions are covered.”
  • Off-grid sanitationLimited

    Off-grid/private sewage disposal inside Ottawa city limits.

    • Privies, privy vaults, septic tanks, cesspools, and other sewage-disposal facilities are unlawful except as provided; a private system may be used where public sewer is unavailable and after obtaining a city permit.
    “Except as provided in this section, it is unlawful to construct or maintain any privy, privy vault, septic tank, cesspool or other facility intended or used for the disposal of sewage. Where a public sanitary or combined sewer is not available for connection, as defined by the Illinois Department of Public Health Private Sewage Disposal Code, the building sewer may be connected to a private disposal system”
  • Mandatory utility hookupSewer (with conditions)

    Properties used for human occupancy, employment, recreation, or another purpose inside Ottawa city limits that abut a street, alley, or right-of-way where a public sanitary sewer is or becomes located.

    • Connection is at the owner's expense; connection is required within 120 days after official notice; the public sewer must be available under the Illinois Department of Public Health Private Sewage Disposal Code.

    connection deadline: 120 days after official notice

    “The owners of all houses, buildings, or properties used for human occupancy, employment, recreation, or other purpose, situated within the city and abutting on any street, alley, or right-of-way in which there is now located or may in the future be located a public sanitary sewer of the city is required at his expense to install suitable toilet facilities therein, and to connect such facilities directly with the proper public sewer in accordance with the provisions of this article within 120 days after the date of official notice to do so, given by the superintendent of water and sewer at the request of the council, provided that the public sewer is available for connection as defined by the Illinois Department of Public Health Private Sewage Disposal Code.”
  • Driveway accessRequired

    New residential driveways inside Ottawa city limits.

    • A concrete driveway apron must meet all City Code requirements on the publicly owned right-of-way.
    “New driveways shall provide for a concrete driveway apron that meets all City Code requirements on the publicly owned right-of-way.”

Still unanswered

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

  • Certificate of occupancy — Occupancy of buildings inside Ottawa city limits.
  • Minimum dwelling size — Dwellings inside Ottawa city limits.
  • Tiny homes — Tiny-home occupancy inside Ottawa city limits.
  • Well permit — Private wells inside Ottawa city limits.

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

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