A plan to open up Chicago’s residential areas to building new small dwelling units such as coach houses and basement apartments will not go up for a vote at the City Council later this month after the initiative met resistance from aldermen.

Supporters of reversing the 63-year-old ban on building accessory dwelling units, often called ADUs or granny flats, say it will “help middle-class people stay in their neighborhoods in the city and provide some of the affordable housing we need,” as Ald. Harry Osterman, 48th, who chairs the City Council’s Housing & Real Estate Committee, put it to Crain’s on Monday.

Osterman is one of five aldermen sponsoring the ADU ordinance that was introduced in May with Mayor Lori Lightfoot’s backing. The notion of permitting ADUs was introduced in 2018 by Lightfoot’s predecessor, Rahm Emanuel, as a way to spur creation of new affordable housing options in increasingly expensive neighborhoods, particularly those where single-family homes predominate.

Osterman said ADUs are a way to “create more housing options” that may suit single people, young adults returning to live with their parents, and retirees.

While his proposal had been scheduled to go up for a vote July 21, Osterman said it’ll be postponed after several aldermen expressed strong opposition at a hearing Friday that lasted more than three hours.

Individual aldermen aired concerns about increasing neighborhood density, absentee ownership of the new units and the difficulty the city would have enforcing a promised prohibition on using ADUs for Airbnb-style short-term rentals, according to WTTW.

That a one-size ordinance may not fit all neighborhoods.

Ald. Pat Dowell, whose 3rd Ward includes a swath of Bronzeville from Roosevelt Road to 55th Street told Crain’s that she supports allowing ADUs, but only if the owner lives in one of the units on-site.

“I have a thousand privately owned vacant lots in my community,” Dowell said. “I’m concerned about someone being able to build extra on that lot without having a principal resident living there.”

The existing ADU proposal does not stipulate any ownership requirements.

Ald. Patrick Daley Thompson, 11th, told Crain’s the proposal could have at least two unintended consequences.

First, in the hot Bridgeport neighborhood, which is part of his ward and where he lives, the ADU ordinance could have the unintended consequence of making property less affordable rather than more.

If owners know it’s permissible to add another rent-generating unit to a residential property, Thompson said, “they’ll charge a higher price for (selling) it,” adding to the escalation in home prices there.

Second, encouraging construction of additional units would intensify development in neighborhoods like Bridgeport when what’s needed to help solve some of the city’s inequities is a push for development in Englewood, Austin and other disinvested areas.

“You’re going to get more vertical growth, but we need horizontal growth in this city,” Thompson said.

Osterman said delaying the vote gives him and others time to resolve the aldermen’s concerns.

“It’s fundamentally important that the city add more units of housing, so we’ll look at how to make this work across all neighborhoods,” he said.