Building permits, zoning and septic rules in Macon County, Illinois

Yes. Unincorporated Macon County, Illinois requires a building permit for new construction and remodeling outside incorporated cities, villages and towns¹. The zoning code specifically requires a permit for any building or structure longer than 10 feet on any side and for any addition¹. The county reviews applications, issues permits and enforces the International Building Code². Illinois also sets a statewide building-code baseline that took effect in 2025, including for jurisdictions without a locally adopted code⁸. Apply before work starts: unpermitted work is illegal, and a late application doubles the permit fee¹. Land and structures used solely for agriculture have a conditional permit exemption, but agricultural structures must still follow building or setback lines⁵.

Macon County Planning & Zoning reviews applications and issues building permits for new construction and remodeling in unincorporated Macon County². Reach the department at (217) 424-1466, or visit 141 South Main Street, Suite 501, Decatur, Illinois². The county publishes a fee schedule and a required-inspections document, but the available material does not provide the project fees or inspection stages; ask the department for both when applying^2,6. A local inspector oversees permitted work, and unpermitted work can cause trouble when the property is sold². We could not confirm an owner-builder exemption, so ask whether the owner may pull the permit and perform the proposed work⁹.

Yes. Macon County Planning & Zoning administers zoning, subdivision, floodplain and stormwater ordinances in unincorporated Macon County². The county also regulates subdivision plats and development, including approval and filing steps and private-sewage planning for proposed subdivisions². Lot size and building height depend on the zoning district^10,11. In the A1 Agricultural District, permitted uses generally require at least 10 acres, with limited routes for certain single-family homes on qualifying tracts of at least 1 acre¹⁰. Ask Planning & Zoning to identify the parcel's district and confirm allowed uses, setbacks and height limits before designing. Incorporated cities, villages and towns have separate jurisdiction².

The property owner must obtain a Macon County Health Department permit before constructing or repairing a private sewage system³. A permit may go to an Illinois-licensed installer or a homeowner installing the homeowner's own residential system, and the county acts on applications within 14 days³. The permit lasts 6 months if construction has not begun³. Environmental Health inspects septic-system construction and installation, and Illinois requires plan approval from IDPH or the local authority before a new system is built, with at least 48 hours' notice before work begins^4,12. The county's ordinance expressly requires inspection of septage disposal sites; the reviewed text does not state that every private system installation must be inspected¹³. These septic rules apply to every address in Macon County, including lots inside incorporated places³. Only about 2.6% of Macon County soils rate free of severe limits for a conventional drain field, so establish wastewater feasibility before fixing the house site¹⁴. Reach Environmental Health at (217) 423-6988, extension 1134, or 1221 E. Condit St., Decatur, Illinois⁴.

Macon County allows manufactured homes as residential dwellings in the RMH1 Single Family Residential District, alongside site-built and modular homes, subject to district height, area and parking rules⁷. That does not establish permission on every parcel, so have Planning & Zoning verify the zoning district before buying or placing a manufactured home. We could not confirm a separate county rule for tiny-home occupancy or a minimum dwelling size; ask Planning & Zoning how the proposed unit would be classified and which district standards apply. Illinois campground licensing rules govern campgrounds, not living in an RV on one's own parcel¹⁵. We also could not confirm whether an RV may serve as a residence on private rural land in unincorporated Macon County; ask Planning & Zoning before relying on an RV for temporary or long-term housing².

1. Confirm the parcel's zoning district, allowed use, lot standard and height limit with Planning & Zoning^2,10,11.
2. Check floodplain constraints before fixing the building site because regulated development needs a county permit¹⁶.
3. Apply to Environmental Health for the septic permit and, if needed, the private-well permit before either system is built^3,4.
4. Submit building and zoning applications before construction begins; applying late doubles the building-permit fee².
5. Schedule the county's required building inspections and Environmental Health's septic installation inspection^2,4.
6. Obtain the certificate of occupancy before occupying a new building or addition¹.

Confirm the parcel's zoning district, lot standard and allowed use with Macon County Planning & Zoning before buying^2,10. Ask whether the building area is affected by the county floodplain ordinance¹⁶. Have Environmental Health evaluate wastewater feasibility because only about 2.6% of Macon County soils rate free of severe limits for a conventional drain field¹⁴. A private water well requires county plan review and a permit⁴. If the parcel touches a state-maintained highway, IDOT requires a permit before right-of-way work, including an access driveway¹⁷. The median property-tax bill is about $2,560 a year at an effective rate near 2.1%¹⁴.