Building permits, zoning and land rules in Grundy County, Illinois

Grundy County expressly requires a building permit when a flood-damaged home in unincorporated Grundy County needs renovation work¹. The available county rule does not establish that every other type of construction requires a permit, so ask the Building Office about the exact project before ordering plans or materials². For those flood-damage renovations, the county reviews plans for compliance with the 2018 International Residential Code and 2017 National Electric Code¹. Qualifying farm residences and agricultural buildings or structures are exempt from the county building-code title only when they sit on a farm that is a farm in fact and their use fits the statutory agricultural definition⁵. We could not confirm a general owner-builder exemption from local building permits, inspections or codes⁹.

Inside municipal limits, Morris¹², Mazon¹³ issue their own building permits. Braidwood¹⁴, Godley¹⁵ also issue their own building permits and extend into Grundy County from Will County. Where a private septic system is allowed on land in Grundy County, septic approval stays with the Grundy County Health Department⁴.

The Grundy County Land Use Department's Building Office handles building permits and plan review for unincorporated Grundy County². The office is at 1320 Union Street, Morris, IL 60450, and the shared Land Use Department number is (815) 941-3120². Office hours are Monday through Friday, 8 a.m. to 4:30 p.m².. For flood-damage renovation permits, the county completes a full plan review and checks that the contractor is properly licensed with Grundy County before issuing the permit¹. The county publishes a 2026 fee-resolution link, but the available record does not establish the amount for a particular project¹. Ask the Building Office for the current fee, required plans, inspections and closeout documents; we could not confirm a general inspection schedule or certificate-of-occupancy requirement⁹.

The county Unified Development Code applies to all development in unincorporated Grundy County³. The Agricultural, Agricultural Residential, Planned Residential, Residential, Commercial General, Commercial Interchange and Industrial districts have an official map maintained at the County Administrative Building¹⁶. Minimum lot size, setbacks and building height vary by district; ask Planning and Zoning for the parcel’s district and dimensional standards^17,18. The UDO includes concept-plan, minor- and major-subdivision, certificate and recording procedures; the planning office also evaluates preliminary and final plats against the Comprehensive Plan and Stormwater Ordinance^19,20.

Morris²¹, Minooka²², Coal City²³, Diamond²⁴, Gardner²⁵ set their own municipal zoning. Braidwood¹⁴, Dwight²⁶, Seneca²⁷, Godley²⁸ also set their own zoning and reach into Grundy County from neighboring counties. Municipal zoning does not replace Grundy County Health Department approval for private septic systems on land in Grundy County⁴.

The Grundy County Health Department's Environmental Health Division administers private sewage disposal systems countywide⁴. A permit is required for a compliant new system and for repairs, and the county says to allow up to 72 hours for review⁴. An approved water and sewage system permit must be in hand before the county will issue a building permit⁴. The Health Department inspects installation work on every private sewage disposal system to confirm correct installation, but the reviewed rule does not establish a universal recurring-inspection interval⁴. USDA rates 0% of Grundy County soils as free of severe limits for a conventional drain field, so do not assume a simple conventional layout will fit without site-specific review²⁹.

In unincorporated Grundy County, camping and travel trailers, excluding mobile homes, may provide temporary housing during construction of a permanent home for no more than 24 months, subject to the UDO’s residential-parcel trailer provisions⁶. County-regulated campgrounds and RV parks may operate as a special use in the Agricultural district, but prohibit permanent residence in an RV or tent⁷. We could not confirm a tiny-home occupancy or minimum dwelling-size rule; ask Planning and Zoning before choosing a dwelling¹⁸. Illinois allows compost toilets and other approved human-waste systems subject to construction and maintenance rules, but other household wastewater still requires a conventional private sewage disposal system³⁰.

1. Confirm that the parcel is unincorporated, then ask Planning and Zoning to identify its zoning district, allowed use, setbacks and any subdivision review^3,16,19.
2. Ask the Building Office whether the proposed work requires a building permit, which application applies and what the current fee is; the county publishes a fee-resolution link¹.
3. Apply to the Health Department for septic approval and any required well permit; septic review may take up to 72 hours^4,8.
4. If the work is a flood-damage renovation, submit plans for county review under the 2018 International Residential Code and 2017 National Electric Code¹.
5. Arrange the required septic installation inspection with the Health Department⁴.
6. For state-road access, obtain an IDOT permit before work; for a county road, ask the Highway Department what approval applies^31,32.

Before closing, confirm whether the parcel is in unincorporated Grundy County and have Planning and Zoning identify its mapped district, allowed use, setbacks and any subdivision constraints^3,16,20. Check septic feasibility early because 0% of county soils are rated free of severe limits for a conventional drain field²⁹. A new, modified or abandoned well requires a permit before work begins, and Grundy County says well applications may take up to 72 hours to process^4,8. Check flood exposure before choosing a homesite: when flood damage reaches 50% or more of pre-flood market value, repairs cannot begin until the structure complies with the floodplain ordinance, potentially through elevation or flood-proofing¹. Property taxes average about 2%, with a median annual bill near $5,260²⁹.