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Zoning Guide

ADU Rules in Chicago, Illinois

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ADU Rules in Chicago, Illinois

Chicago is the third-largest city in the United States and one of America's great urban centers. In December 2020, Chicago passed the ADU Ordinance — a major housing policy reform allowing accessory dwelling units (coach houses, garden apartments) in residential zones. Illinois has no statewide ADU preemption law — Chicago's local ordinance governs.

Chicago ADU Ordinance (2020)

Chicago's ADU Ordinance (effective 2021) allows:

  • Coach houses (detached ADUs in rear yards of 2-flat, 3-flat, and single-family lots)
  • Garden apartments (basement/ground-floor units with separate entrance)
  • Conversion ADUs (converting existing attic or basement space)

The ordinance initially applied to five pilot area zones — verify current coverage at chicago.gov/adu.

Permitted ADU Types

ADU Type Description
Coach House New or existing detached structure in rear yard
Garden Apartment Below-grade or ground-floor unit with separate entrance
Attic Conversion Converting existing attic space to a dwelling
Basement Conversion Converting basement to a separate unit

Pilot Area Eligibility

Chicago's ADU Ordinance initially applied to specific pilot areas. As of 2023, the program was expanding. Verify your address is in an eligible zone at the Chicago Department of Planning and Development's ADU portal.

Size Limits

  • Coach House: Maximum 1,000 sq ft (2 floors allowed)
  • Garden Apartment: Per existing building footprint
  • Coach house height: Maximum 2 stories

Setbacks (Coach Houses)

  • Rear: Minimum 2 feet from rear property line
  • Side: Per base zone
  • Must be at least 10 feet from primary dwelling

Affordability Requirement

Properties with 3+ units that add an ADU must keep at least one unit at affordable rent rates. Verify current affordability requirements with Chicago DPD.

Flood Zone Considerations

Parts of Chicago near the Chicago River and lakefront may have flood zone considerations. Verify FEMA flood map status.

Permit Process

  1. Verify pilot area: Confirm your address is in an eligible ADU zone at chicago.gov/adu
  2. Pre-application: Chicago DPD provides pre-application guidance
  3. Submit plans: Chicago Building Department
  4. Zoning compliance: Verify compliance with ADU Ordinance
  5. Building permit and inspections
  6. CO: Required before occupancy

Contact

Chicago Department of Planning and Development 121 North LaSalle Street, Room 1000, Chicago, IL 60602 Phone: (312) 744-5777 Website: chicago.gov/city/en/depts/dcd/supp_info/adu.html

Disclaimer: Chicago's ADU program has been evolving since 2021. Verify current pilot area coverage and ADU standards with Chicago DPD before starting any project.

More about Chicago Zoning

Sources

  1. Chicago ADU Ordinance (2020) — Zoning Code Amendment·codelibrary.amlegal.com·Accessed 2026-05-24·Direct link
  2. Chicago Zoning Ordinance (Title 17)·codelibrary.amlegal.com·Accessed 2026-05-24·Direct link

FAQ

Are ADUs allowed in Chicago, Illinois?
Yes. Chicago passed the ADU Ordinance in December 2020, which allows additional dwelling units in residential zones within designated pilot area zones. The ordinance has been expanding to cover more of the city.
What is Chicago's ADU pilot program?
Chicago's 2020 ADU Ordinance initially applied to five pilot area zones covering approximately one-third of the city. The program was designed to expand to citywide coverage. Verify current pilot area boundaries with the Chicago Department of Planning and Development or the Department of Housing.
What types of ADUs does Chicago allow?
Chicago allows coach houses (detached ADUs in rear yards, historically legal before being banned in 1957), conversion units (basement, cellar, and attic conversions in existing 2-7 unit buildings), and additional attic/cellar units in eligible zones within pilot areas.