Building footprints. Data from the City of Chicago and OpenStreetMap

This spring, City Council could consider lifting the ban on “accessory dwelling units” in Chicago. Accessory dwelling units, or ADUs, are a form of apartment most commonly seen in Chicago’s neighborhoods as coach houses behind a bigger house (also called rear houses if the main building doesn’t have a garage). Other types include attic and basement apartments. They’re known as “granny flats” and “laneway houses” in other cities.