Chicago’s Approves “Granny Flat” Expansion With Compromises

A long-delayed plan to legalize casitas and granny flats across Chicago is moving forward, but only after aldermen scaled it back with restrictions designed to protect single-family neighborhoods.

Aldermen Bennett Lawson and Marty Quinn ended a year-long stalemate over the citywide expansion of accessory dwelling units, or ADUs. Their compromise kept Quinn’s union-backed amendment requiring contractors to hire through certified apprentice programs for new construction, Crain’s reported. The Chicago Federation of Labor and building trades had pressed hard for the measure, warning they would sink the ordinance otherwise.

The compromise, however, also gave aldermen near-total control over ADUs in single-family zones. Detached units will be banned 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.

The legislation also scrapped a 700-square-foot size cap on coach houses but maintains a 22-foot height limit and other spacing rules. A Chicago City Council vote is expected Thursday.

Lawson 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.

“If you could build a two-flat, you can build an ADU,” Lawson said. “This is a citywide ordinance. It’s a big expansion.”

But Quinn and allies 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. Johnson struck a diplomatic tone, saying he was “grateful” the measure advanced despite aldermanic resistance.

The compromise leaves Chicago with a narrower ADU policy than housing advocates hoped for, but it marks the first meaningful expansion since the city launched a limited pilot program in 2021.

— Eric Weilbacher