Thinking Small

Chicago introduces highly anticipated ADU ordinance

What lies behind: To boost density in established Chicago neighborhoods, a new ordinance would streamline the permitting of accessory dwelling units, or coach houses in Chicago-speak. (Cragin Spring/Flickr)

Following months of anticipation and a well-publicized push from the Chicago arm of the Urban Land Institute (ULI), Chicago Mayor Lori Lightfoot and her administration have introduced an ordinance that would reverse the ban on, and streamline the permitting of, coach houses and other types of accessory dwelling units (ADUs) that already exist or could be built on vacant residential lots or as additions to existing buildings.

Prevalent across older Chicago residential properties, coach houses are small and often garage-less rear outbuildings also known as laneway houses, rear houses, granny flats, or carriage houses. Currently, coach houses (also a Chicagoan catchall term for any additional freestanding structure on a property, modern or not, that could be used for habitation) cannot be used as primary standalone residential units without cumbersome and expensive zoning changes. The ordinance, which has been formally introduced to the City Council and will be reviewed by the zoning and housing committees, would strike the ban on ADUs as a means of boosting density and generating affordable housing in the city.

As the Chicago Sun-Times explained earlier this month, ADUs have effectively been outlawed in the city since a 1957 overhaul of the city’s zoning codes. Coach houses, however, continued to pop up across the following the ban while existing structures—and there are many, roughly 2,400 per data shared by the Chicago Cityscape blog—were grandfathered in.

a coach house, a typical chicago adu

A typical Chicago coach house. (Daniel X. O’Neil/Flickr)

“The need for safe and affordable housing is likely to increase as more households in the Chicago region face unemployment and rising economic uncertainty due to the COVID-19 pandemic,” wrote the ULI in a report, “Unlocking Accessory Dwelling Units in Chicago,” published earlier this month. “Accessory Dwelling Units provide an innovative way for Chicago to address the growing housing challenge by adding to its inventory of affordable housing, providing financial stability for homeowners and by energizing neighborhoods.”



Per Steven Vance of Chicago Cityscape, who broke the news of the ordinance’s arrival, the law, if adopted, would take effect on August 1, 2020, a date that coincides with the mandatory implementation of the 2019 Chicago Building Code for all renovation and new construction projects. Chicago Cityscape notes that the ordinance categories ADUs into two categories: Coach houses and conversion units, the latter of which entail renovations and/or additions to existing buildings over 20 years old. “Only units built according to this code would be considered conversion units; units that exist on or before July 31, 2020, that seem like conversion units are not considered conversion units,” elaborated Vance.

Furthermore, the ordinance states that coach houses cannot be built on a lot with a conversion unit, although property owners in the appropriate residential zoning districts can potentially build or add more than one coach house or conversion unit on a single lot, just not both. There are, however, some stipulations depending on the size and age of the existing “front” residential building on the lot. There are also rules that dictate the affordable nature of coach houses and conversions when multiple units are involved. Chicago Cityscape gets into the nitty-gritty of special rules that apply—or don’t apply—to specific residential zoning districts.

What’s more, existing coach houses can be modified and potentially expanded, while newly built coach houses will be limited to a maximum of 700 square feet or 60 percent of the required rear setback. There are no direct limits on the size of conversion units.



The ordinance also stipulates that ADUs and conversion units cannot be used as Airbnb properties and do not require additional parking.

Much like the ULI, the Lightfoot administration sees the rehabilitation of existing coach houses as well as the construction of new ADUs and conversion units as a necessary way to boost much-needed affordable housing in the city. These new living spaces, as the administration points out, are pandemic-friendly, to boot.

“The administration’s proposed ADU ordinance is not only a way to increase available housing throughout Chicago, it is also a safety and stimulus effort, designed to allow for very gentle density within existing neighborhood character,” the Department of Housing explained to the Sun-Times in a statement. “In fact, if ever the need arises again, ADUs will create a type of density that could allow for multi-generational households to remain close, but also create options for social distancing in a basement unit or coach house on the same property.”

This all being said, although the ordinance, which has been in the works for well over a year, has now been introduced to City Council, it’s not entirely clear when it will be taken up considering the unprecedented circumstances.

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