Chicago’s Additional Dwelling Units Ordinance changed beyond its original pilot. The City says the City Council expanded the ordinance beyond the five pilot areas in September 2025. Start with the address lookup on the City’s ADU program page, then check the current eligibility map and Municipal Code §2-44-106 for the parcel and proposed form.
Match the project to the local form
The City distinguishes a conversion unit connected to an existing building, such as an attic or basement, from a coach house in a separate detached structure. Those labels identify different project forms; they do not establish that a property is eligible. Use the City’s current address map and code rather than an old pilot-area list.
Keep pre-certification separate from permission to build
The Department of Housing’s pre-certification is an early eligibility step. The City expressly warns that a pre-certification letter does not guarantee that a project is permissible. After it is issued, required permits from the Department of Buildings are still needed before construction.
A citywide expansion does not make every lot eligible. Check the current map, code conditions, property and project facts, and any later amendments with the City. The City page provides a screening and process route, not a parcel approval.