Chicago, IL Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Chicago, IL, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Ordinance
- SO2024-0008918 (passed 9/25/2025)
- Effective Citywide
- April 1, 2026
- Coach House Height
- 22 ft max; rear 50% of lot
- Parking
- No additional spaces required
- Labor Standard
- Reg. Apprenticeship Program (coach houses)
Summary
Chicago authorizes garage conversions to coach houses (detached ADUs) and conversion units (attic/basement ADUs) under the Additional Dwelling Unit Ordinance. The pilot ordinance (effective May 2021) was made permanent and city-wide by Ordinance SO2024-0008918, which the City Council passed 46-0 on September 25, 2025, with permits accepted starting April 1, 2026. ADUs are now allowed in single-family zones within the original pilot areas plus all multifamily zones citywide (except downtown).
The Additional Dwelling Units (ADU) Ordinance was first approved by Chicago City Council in 2020, resulting in the creation of five ADU Pilot Areas. In September 2025, City Council voted to expand the ADU ordinance beyond the pilot program allowing for ADU access more broadly across Chicago. The City of Chicago Municipal Code distinguishes ADUs between "conversion" and "coach house" units. A conversion unit is connected to the existing building such as within an attic or basement while a coach house is a separate, detached structure.
Full Breakdown
Under Chicago's Additional Dwelling Unit Ordinance (Municipal Code Title 17, Zoning), the City distinguishes between Conversion Units (created within an existing building such as an attic or basement) and Coach Houses (detached structures, often above a converted garage). A garage may be converted into or replaced by a coach house in the rear 50% of the lot, subject to a 22-foot height limit. The ordinance does not require additional off-street parking when an ADU is added. The new city-wide ordinance (SO2024-0008918, effective April 1, 2026) expands the eligible area by approximately 135% beyond the original five pilot zones, and applies a Registered Apprenticeship Program labor standard for general contractors and subcontractors performing coach house work. All ADU projects require a pre-certification approval from the Department of Housing and a building permit from the Chicago Department of Buildings (DOB). Existing two-flat and multifamily buildings may also add basement/attic conversion units citywide outside downtown.
Violations & Fines
Converting a garage to habitable space or constructing a coach house without DOB permits is a violation of the Chicago Building Code (Title 14X) and Zoning Code (Title 17), with stop-work orders, fines from $200 to $1,000 per day under Municipal Code §1-4-090, and required after-the-fact permits or restoration. Failure to comply with the apprenticeship labor standard on a coach house permit can result in permit revocation.
Frequently Asked Questions
Can I legally convert my Chicago garage to a coach house?
Do I need a permit to remodel or convert my Chicago garage to living space?
Do I need additional parking after converting my Chicago garage?
Sources & Official References
Other rules in Chicago
Compare Chicago to another location·View the Illinois accessory structures overview
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Garage Conversions in Nearby Cities
How other cities in Cook County handle garage conversions.