Illinois Building Codes

LOCAL ADOPTION with state minimums. No mandatory statewide residential building code. Individual municipalities and counties choose whether to adopt codes and which editions. Chicago uses entirely separate Chicago Building Code (NOT ICC). Illinois Energy Conservation Code (IECC-based) applies statewide. Illinois Roofing Industry Licensing Act requires statewide roofing contractor license (IDFPR). Home-rule municipalities (pop >25,000) have significant autonomy. Many rural/unincorporated areas have limited or no building code requirements. Climate Zones 4A (south) and 5A (north/central). Ice barrier required statewide. Frost depth 30-48 inches.