Chicago property owners can now build coach houses or legalize basement apartments in more areas of the city, following an expansion of the Additional Dwelling Units (ADU) program, according to an April 1 announcement. The new ordinance allows these units to be constructed citywide without requiring a zoning change, with certain restrictions based on location and ward participation.
The expansion is intended to address housing needs by increasing density in residential neighborhoods while providing clear rules for property owners. About 60 percent of Chicago’s residential and mixed-use areas are now eligible for additional dwelling units, up from around 20 percent under the previous pilot program.
Steven Vance, co-lead of Abundant Housing Illinois, said, “Going from pilot to permanent is huge. That’s probably the best part of this. The geographic expansion … that’s great, but now we actually can rely on this going forward, that we’ve established the rules.”
The Department of Housing will oversee eligibility and has launched a dedicated website and online map to help property owners determine if they qualify. Commissioner Lissette Castañeda said, “Stop No. 1 is with us, coming in, checking, ‘Am I able to build an ADU?’ And then from there, getting the pre-certification from [the housing department] that you are able to take over to the Department of Buildings.”
Since its start as a limited pilot in 2021—which permitted about 350 units—interest has grown: as of March 18 this year, over 800 additional dwelling units had been pre-certified by the department. Most approvals have been concentrated on Chicago’s North or Northwest Side.
A compromise between Aldermen Marty Quinn and Bennett Lawson allowed alderpeople across wards outside original pilot zones to opt their areas into eligibility with varying restrictions such as annual limits per block or requirements for homeowners to live onsite.
Contractors building new coach houses must participate in a U.S. Department of Labor apprenticeship program; however, this rule does not apply when converting existing basements or attics into living spaces.
Some residents have created resources like aduchecker.com—a site built by Logan Square neighbor Gaurang Telang—to help others navigate eligibility before applying through official channels.
Castañeda said her department aims “to make sure that all interested neighbors are be able to navigate the process successfully.” She added: “This is gentle density; we’re not completely changing the character of a neighborhood… This just gives [us] that ability to build more housing in a way that is not overwhelming in neighborhoods and communities.”
