Chicago will soon adopt an ADU ordinance
An Accessory Dwelling Unit (ADU) is an "extra" home at a residential property. The ADU can be inside the existing building, or a new backyard home on an improved or vacant lot. The City of Chicago has a proposed ordinance that would legalize the new construction of backyard homes.
Backyard homes (also called detached ADUs, coach houses, and rear houses) are separate buildings and have their own utility connections. The proposed ordinance wouldn't allow an interior ADU if the property owner elects to build a backyard home, and it would limit the size of backyard homes.
Mark Pomarico and James Young, architects at Booth Hansen, have created a "zoning worksheet" that helps property owners determine how large of a backyard home they would be allowed to build.
How to use the worksheet
Find the survey you obtained when you bought your property. The survey has the lot width and lot depth dimensions that are needed to fill out the zoning worksheet.