The Department of Buildings

Illegal Conversions

A Certificate of Zoning Compliance certifies the number of residential dwelling units for a property that are legal under the Chicago Zoning Ordinance.

An Illegal Conversion is the addition of a separate dwelling unit above the number of residential units designated for that residential property in the Certificate of Zoning Compliance.

Illegal conversions may pose a serious life-safety threat to all residents of the property. It is highly probable that the illegal unit may lack adequate ventilation, ceiling height and natural lighting as well as lack adequate exiting in the event of a fire or other emergency.

Most illegal conversions are basements or attics which have been turned into separate rented apartment units or an existing single dwelling unit which is partitioned into two dwelling units.

Buildings with over 4 residential dwelling units require private garbage containers and pick-up. Illegal conversions may result in the building forfeiting City garbage pick-up.

You may need to obtain a permit for the de-conversion of basement or attic units.

If you know of or suspect an illegal conversion in your neighborhood, you may contact 311 City Services, who will route your call to the appropriate City department(s) for inspection and enforcement action.