Illinois ADU Rules

ADU Rules in Illinois (2026)

ADU rules in Illinois — no statewide ADU law. Regulation is entirely local. Key provisions and city-specific frameworks for accessory dwelling units.

Preempts Local Ordinances

No — local rules may be stricter

Has State Law

No — regulation is local

Official Source Could Not Be Reached

Source unreachable

The official government source for this jurisdiction could not be reached to confirm or deny a statewide preemption statute. Regulation is local until otherwise confirmed.

Local Control Framework

  • No statewide ADU preemption or mandate law exists in Illinois as of 2026 · Source

  • ADU regulation is left entirely to local municipalities under Illinois Municipal Code (65 ILCS 5) · Source

  • Chicago enacted its own ADU Ordinance (2020, expanded 2022) allowing both attached and detached ADUs citywide · Source

  • Evanston, Oak Park, and other suburban municipalities have adopted their own ADU-permissive ordinances · Source

  • Illinois has no statewide housing compact or state-mandated zoning reform · Source

Legislative History

2020 — Chicago ADU Ordinance O2020-5816 · Source

Chicago (local, not state law) enacted ADU Ordinance allowing coach houses and basement apartments in 5 pilot areas · Source

2022 — Chicago ADU Ordinance Expansion O2022-1679 · Source

Chicago (local, not state law) expanded ADU Ordinance to all city neighborhoods, allowing both attached and detached ADUs citywide with owner-occupancy requirement · Source

Source: Illinois Local Zoning Authority. Last verified April 3, 2026. View source

Last updated: April 3, 2026
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Illinois ADU Rules (2026) — Local Control & City Frameworks | PropertyZoned