Chicago legalised ADUs citywide; your declaration may still say no
Chicago legalised ADUs citywide; your declaration may still say no
2026-09-10 · Illinois · Regulation
What happened. Chicago's Additional Dwelling Unit pilot became permanent and citywide by amendment to Section 17-7 of the Chicago Zoning Ordinance, effective April 1, 2026. The City Council passed the expansion unanimously on September 25, 2025, and a December 2025 follow-on vote added further single-family districts.1
A note on the record: the ordinance is identified as SO2024-0008918. We could not open the enacted text — chicago.gov refused automated retrieval — so the ordinance number is unverified.
The scale
Eligible parcels rise from roughly 116,000 to over 320,000 — about 60% of the city, an increase of about 135% in eligible area, ending a nearly seventy-year prohibition on coach houses, basement apartments and attic conversions in most neighbourhoods.
What is permitted where
ADUs are permitted by right in RT, RM, B and C districts (downtown excluded), and in RS-zoned areas within aldermanic opt-in areas; they are allowed in single-family zones in 34 of 50 wards, with single-family construction eligibility now reaching 28 wards.
Two forms: coach houses (accessory structure, code cite 17-9-0201-F) and conversion units (attic or basement, cite 17-9-0131).
- Properties with 1–4 units: one coach house or one conversion unit.
- Properties with 5 or more units: no coach house, but conversion units up to 33% of the existing legal unit count.
Adding two or more ADUs triggers affordability: 50% of the ADU units must be rented at or below 60% AMI for 30 years.
The sentence boards need
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