Attic rooms

In the early days of zoning, a building’s size was controlled mostly by height and setback restrictions. Later, we added control of the building’s volume, called “Cubical Content” but in the 1950’s Chicago started to use “Floor Area Ratio” instead.

The F.A.R. is a ratio of the usable floor area of the building to the size of the lot it sits on. An F.A.R. of .9 meant that you could build a one story ranch house that covered 90% of your lot, or a 2 story that covered 45%.

At some point, while defining what part of the floor area is usable, the zoning department turned to attics.

Every municipality seems to have developed its own standard. Some said that unfinished attics don’t count, but finished ones do. Some said that the floor space of a finished attic with a ceiling height of 5 feet or more count. Chicago’s ordinance said “those portions of an attic having head-room of 6 feet 9 inches or more” were usable floor area.

This has always been understood to mean finished or unfinished. If you wanted to drywall your attic, zoning did not care. Unless you increased the amount of usable floor area by adding dormers, it was not a zoning concern.

The 2004 ordinance says almost precisely the same thing. However, they added the definition of an attic. Section 17-17-0213 says that an attic is “Unfinished floor space located immediately below a gabled roof or other form of sloped roof”.

The zoning department has interpreted this to mean any portion of a finished attic constitutes usable floor space. Now, if your rebellious teenager needs more privacy or you want someplace to put your desk, think twice about using your attic.

You may need a zoning change just to hang a few sheets of drywall.

Paul K. Dickman