After a series of delays and contentious debates, Chicago City Council passed a citywide ordinance allowing accessory dwelling units — also known as granny flats — with more restrictions than housing advocates would have liked.
An original version of the ordinance would have allowed ADUs throughout most of the city with few barriers to the approval process. But a debate about aldermanic control over individual ADU proposals turned into a year-long stalemate.
As a compromise, the ordinance approved Thursday bans detached units in low-density districts unless a local alderman opts in. Even then, construction will be capped at one to three ADUs per block, depending on zoning. Detached houses that add an ADU must be owner-occupied. For multi-unit districts, ADUs will be allowed by right.
Still aldermen, industry groups and the mayor celebrated the outcome.
“This ordinance offers a practical, balanced solution that supports both renters and the long-term health of Chicago’s housing market,” said Michael Mini of the Chicagoland Apartment Association. “Our collective efforts should prioritize developing more housing options, particularly housing that is affordable to local residents who need them most.”
Aldermen Marty Quinn’s union-backed amendment requiring contractors to hire through certified apprentice programs for new construction also remained attached to the new ordinance. The Chicago Federation of Labor and building trades had pressed hard for the measure, warning they would sink the ordinance otherwise.
“I feel this revised ordinance better represents Chicago’s values by lifting up our labor unions and workers,” Quinn said. “Chicago is a union town, and including our labor unions in this process was critical.”
The legislation also scrapped a 700-square-foot size cap on coach houses but maintains a 22-foot height limit and other spacing rules.
Alderman Bennett Lawson, who originally proposed the ordinance, had pushed for a broader legalization effort, framing ADUs as a way to chip away at Chicago’s estimated 120,000-unit affordable housing shortage by creating unsubsidized, naturally occurring affordable units.
Lawson said the new version of the ordinance should still help the city’s housing needs.
“This is something that is very impactful,” he said “It will bring hundreds of new units, hopefully a year, but in ways that you may not even notice in a neighborhood.”
Quinn and his allies, however, leveraged organized labor’s support to force concessions, arguing aldermen must retain veto power over zoning changes in their wards. The compromise underscores the council’s long-standing practice of “aldermanic prerogative.”
Progressives, including Mayor Brandon Johnson, had championed ADUs as a modest but citywide affordability fix.
“By expanding ADUs to communities across the city, we are increasing housing availability and driving sustainable neighborhood investment,” Johnson said.