The city of Chicago is known for many things. It is known as The Windy City more for its politics than for its weather. It is well known as the home for many of the works of architect Frank Lloyd Wright. It is the home of the Merchandise Mart which is the only building in Chicago (and maybe the country) that has its own zip code (60654).
Skunks usually nest in burrows constructed by other animals, but they also live in hollow logs or even abandoned buildings. In colder climates, some skunks may sleep in these nests for several weeks of the chilliest season.
What to do if a skunk is living under the shed or deck. Your first option is to do nothing at all. Skunks typically live in dens for short periods. Skunk babies are independent by the end of summer, when they leave the den and disperse from their family group. If you can wait until the babies are grown and/or have left, you can then close off the access point to prevent other animals from using the attic as a den in the future.