ADU Rules in Chicago, Illinois

Chicago's current zoning code treats Additional Dwelling Units (ADUs) as either conversion units or coach houses. The old 2020 "five pilot areas" description is no longer sufficient as a current summary because the present code now contains zoning-district-specific ADU permissions and restrictions.

Conversion Units

A conversion unit is a dwelling unit created or rehabilitated inside a principal residential building that has lawfully existed for at least 20 years and is established under the current zoning-code provisions.

Current use tables allow conversion units in multiple residential, business, commercial, and downtown contexts, subject to the applicable zoning provisions.

Coach Houses

A coach house is an ADU located in an accessory building.

Current §17-9-0201-F includes important standards such as:

• one dwelling unit per coach house;
• maximum building height of 22 ft;
• at least 3 ft of open space along at least one side property line, unless the side abuts an alley or street;
• normally 15 ft separation from the principal building, with a possible administrative reduction to 10 ft on qualifying shallow lots;
• no accessory parking is required for the coach house itself.

RS Zoning Districts

RS districts have a separate framework.

Current §17-7-0570 establishes Additional Dwelling Unit-Allowed RS Areas and can impose:

• annual limits by RS district;
• owner occupancy for the detached house at pre-certification; and
• administrative-adjustment requirements.

Therefore, a Chicago address should be checked against its exact zoning district and, for RS zoning, the current ADU-Allowed RS Area provisions.

Short-Term Rentals

Chicago's licensing code restricts conversion units and coach houses from short-term-rental use in the circumstances stated in the current Municipal Code.

Official Sources

Chicago Municipal Code §2-44-106 — Additional Dwelling Units

Chicago Zoning Ordinance §17-9-0201-F — Coach Houses

Chicago Zoning Ordinance §17-7-0570 — ADU-Allowed RS Areas

Disclaimer: Confirm the current zoning district and ADU eligibility before preparing permit drawings.