Building permits, zoning and septic rules in St. Clair County, Illinois

Yes. In unincorporated St. Clair County, an owner or authorized agent must obtain a permit before constructing, enlarging, altering, repairing, moving or demolishing a regulated building, changing its occupancy, or doing regulated electrical, gas, mechanical or plumbing work¹. Listed exemptions include sidewalks, driveways, concrete patios, siding and replacement windows or doors, but the exemptions do not cover every repair¹. St. Clair County has partly adopted the 2012 International Building Code and 2012 International Residential Code with local changes¹. Permitted work must remain accessible, and the permit holder must request inspection before work advances past each inspection point¹. A new building cannot be used or occupied until the building official issues a certificate of occupancy; a temporary certificate may be available for a safe portion of an unfinished project¹.

St. Clair County Building & Zoning Department is on the 5th floor of the county building at 10 Public Square in Belleville⁸. The department handles building, electrical and occupancy permits, zoning, flood-zone determinations, and building and occupancy inspections⁸. Before applying, obtain an assigned property address from the 9-1-1 Coordinating Office⁵. Apply to the building official with any required construction documents, pay the applicable fees before issuance, post the permit, and request inspections before successive work is covered¹. East Carondelet, Fayetteville, Freeburg, Lenzburg, Marissa, Millstadt, New Athens and St. Libory contract with St. Clair County for building inspections⁵. Inside another municipality, ask that municipality which office issues permits because the county requirement described here applies to unincorporated St. Clair County¹.

Yes. St. Clair County zoning applies to unincorporated land and municipalities without their own zoning, but excludes property occupied by Scott Air Force Base². The published districts carry their own use, lot, yard, coverage and height standards, so identify the parcel's district before choosing a house site⁹. Minimum lot area ranges from examples such as 40 acres in A to 10,000 square feet in SR-3⁹. Front, side and rear setbacks vary by district and include exceptions in the table notes⁹. The general principal-building height limit is 35 feet, although governmental structures may reach 100 feet and other special rules may apply⁹. Qualifying agricultural buildings remain subject to setback lines, and a residence or building not used exclusively for agriculture still needs a building permit⁶. The county's published zoning-compliance letter fee is $30⁸.

St. Clair County Health Department administers the private-sewage program, and the county code incorporates Illinois licensing and disposal rules³. Obtain a county permit before constructing, altering or extending an individual domestic sewage system; the fee is $300, and routine tank-cover replacement, cleaning and inlet or outlet rodding are exempt from that construction permit⁴. The permit may be issued to a homeowner or a St. Clair County-licensed private-sewage installer⁴. State rules also require plan approval before construction and at least 48 hours' notice before installation, repair or modification begins¹⁰. Only 10.1% of St. Clair County soils rate without severe limits for a conventional drain field, making site and soil evaluation especially important⁷. The Health Department must refuse a private-system permit when a sanitary sewer is available within 300 feet for a single-family property or 1,000 feet for specified commercial, multifamily or subdivision projects⁴.

We could not confirm that St. Clair County allows long-term RV living or tiny-home occupancy on private land; ask Building & Zoning about the parcel's district and proposed use before buying⁸. County zoning treats a private recreational area or nonprofit camp as a special use where that provision applies, so temporary camping is not automatically allowed by that rule⁶. Manufactured homes are limited by zoning district and local siting rules: the MHP district is intended for permanent occupancy in manufactured-home parks, and manufactured housing is prohibited in the AO-3 Installation Buffer⁶. A county permit for a manufactured or modular home is $150, or $300 when placed over a basement¹. Illinois permits certain privies and specialized toilets for human waste, but other household wastewater must still go to a conventional private sewage system¹¹. In county-zoned areas using individual water or sewage, the Health Department must approve facility locations³.

1. Obtain the parcel's assigned address from the county's 9-1-1 Coordinating Office⁵.
2. Confirm the zoning district, allowed use, lot area, setbacks, lot coverage and height rules with Building & Zoning^6,9.
3. If public water or sewer is unavailable, obtain Health Department approval for private facilities; a septic permit is $300 and a new or renovated well permit is $200⁴.
4. Submit the building application and required construction documents, then pay the applicable fees before issuance¹.
5. Post the permit and request inspections before covering each successive stage of work¹.
6. Obtain the building official's release before connecting utility, energy, fuel or power service; the official may authorize a temporary connection¹².
7. Complete final inspection and obtain a certificate of occupancy before using the building¹.

First confirm whether the parcel is unincorporated or inside a municipality, because the county building and zoning rules described here apply to the county jurisdiction^1,2. Check the zoning district, legal access and flood status before choosing a building site^1,6,9. Land abutting a designated Major Area Service Highway needs written Special Highway Access Permit approval from the County Highway Engineer before grading or building-permit issuance⁶. Work in a flood-hazard area requires lowest-floor elevation documentation before final inspection¹. Dividing unincorporated land requires an approved plat before recording; preliminary review costs $40 per lot or tract with a $300 minimum, and final review costs $25 per lot or tract with a $100 minimum¹³. The nearest city of 100,000 or more is about 19 miles from the county center⁷. Test soils before assuming a standard septic field will work because only 10.1% of county soils rate without severe limits for a conventional drain field⁷.