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

PBZ’s Building Division issues building permits for new construction in unincorporated Kendall County and in the villages of Millbrook and Plattville¹. Inside Oswego the Village issues building permits², and inside Yorkville the City does³. The parts of Joliet¹² and Sandwich¹³ that reach into Kendall County also issue their own. Septic permits do not move to any city: unsewered Kendall County addresses stay with the Kendall County Health Department⁴. The county’s updated codes began taking effect May 11, 2026 and include the 2024 International Residential Code, 2024 International Building Code and 2023 National Electrical Code¹⁴.

Start with the Kendall County Planning, Building & Zoning Department at its Yorkville office for building permits and zoning questions on unincorporated land^1,6. PBZ also handles building permits inside Millbrook and Plattville¹. Kendall County does not accept emailed building-permit applications or supporting paperwork¹. Building-inspection requests must be submitted by 4:00 p.m. at least one business day before the requested inspection; no specific inspection time is promised¹. Kendall County does not register, bond or license contractors working in unincorporated areas¹.

Kendall County publishes zoning districts for county areas, Millbrook and Plattville; county rules below concern unincorporated land⁶. Oswego¹⁵, Yorkville¹⁶, Montgomery¹⁷, Plano¹⁸, Newark¹⁹ administer their own zoning. Aurora²⁰, Joliet²¹, Plainfield²², Minooka²³, Sandwich²⁴ also have their own zoning and reach into Kendall County from neighboring counties. Septic permits in unsewered Kendall County remain with the Kendall County Health Department⁴. County accessory-building standards generally require 5 feet from side and rear property lines and 10 feet from the primary structure, with exceptions for attached buildings; ask PBZ about front-yard setbacks¹¹. In the A-1 Agricultural District, accessory structures need 150 feet from adjacent road centers or 100 feet from dedicated road rights-of-way, whichever is greater, and 10 feet from separately owned property lines¹¹. Accessory structures cannot occupy recorded easements or encroach on private septic systems or wells¹¹.

The Kendall County Health Department regulates the design, construction, operation, maintenance and service of onsite wastewater systems, and a permit is required before installation, repair or renovation^4,25. Before applying, obtain a soil evaluation from a state-certified soil classifier, then submit the soil analysis, detailed site drawing, completed forms and required fees⁷. The department reports a review period of 10 to 14 working days after receiving complete paperwork and fees²⁵. Health Department approval must come before PBZ begins building-permit review, and septic inspections require at least 24 hours' notice⁷. Only 0.1% of county soils are rated “not limited” for a conventional drain field, so make the soil evaluation an early feasibility test rather than assuming a standard field will fit²⁶.

We could not confirm permission for long-term RV occupancy or tiny-home living on private land in unincorporated Kendall County; ask PBZ about the parcel’s zoning district and proposed dwelling before buying^1,6. Illinois campground rules do not establish permission for residential RV use on a private parcel²⁷. Small houses still fall under Kendall County’s new-construction building-permit requirement¹. The A-1 Agricultural District ECHO conditional-use provision allows one manufactured home on a separate ground area of at least 5 acres, subject to health codes, setbacks, occupancy eligibility and annual affidavits; that provision does not establish general manufactured-home permission²⁸.

1. Ask PBZ whether the parcel is under county or municipal jurisdiction; use the applicable office to confirm zoning approval and building-permit requirements^6,29.

1. Confirm every setback before ordering plans; accessory-building standards include separate general and A-1 Agricultural District measurements¹¹.

1. If the site needs septic, obtain the certified soil evaluation and submit the septic-permit package to Environmental Health⁷.

1. If the home needs a private well, obtain the Health Department well permit before construction or repair begins⁸.

1. Identify the road authority before changing access; Kendall County Highway handles right-of-way work permits for county highways³⁰.

1. Obtain Health Department well and septic approval before PBZ begins building-permit review, then schedule the required inspections^1,7.

Confirm jurisdiction and the published zoning district first because zoning approval and building-permit authority vary among county and municipal areas^6,29. If an accessory building is planned, map easements, the septic system and the well before siting it, then confirm whether the general or A-1 Agricultural District setbacks apply¹¹. Test septic feasibility early: only 0.1% of soils are rated “not limited” for a conventional drain field²⁶. A Kendall County Health Department permit is required for well construction, repair, capping or sealing in its service area⁸. Verify legal road access with the authority that owns the road before planning right-of-way work³⁰. Most county land is relatively gentle, with 98.9% at a slope of 15% or less, but site-level drainage and flood conditions still need parcel review²⁶. The effective property-tax rate is about 2.5%, and the median annual bill is about $7,556²⁶.