Illinois ADU Laws & Rules (2026)

Compare ADU zoning rules across 2 Illinois cities. Average ADU score: 7.0/10.

Avg Score: 7.0/102 Cities

Key Illinois ADU Laws

Illinois ADU Overview

  • 2 cities currently covered with detailed ADU zoning data
  • Average ADU-friendliness score: 7.0/10
  • Rules vary by city — check individual city pages for details
  • We're actively expanding coverage in Illinois

Illinois Cities ADU Comparison

CityMax SizeSetbacksPermit FeesBuild Cost1BR RentScore
Chicago Detached coach houses governed by bulk/setback standards rather than a flat sq-ft cap (limited to 60% of the required rear setback area); Confirm buildable size with Chicago Dept. of Housing for your lot Detached ADU must sit within the rear 50% of the lot; Confirm with Chicago Dept. of Housing $2,800-$4,500 $150,000-$300,000 $1,450-$1,950/mo 7/10
Evanston 1,000 sq ft 12 feet $2,500-$4,000 $140,000-$280,000 $1,500-$2,000/mo 7/10

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