430 ILCS 180/5

In this Act: "Court" means an open space on a lot, other than a yard or portion of a yard, that is unobstructed from its lowest level to the sky and bounded, in whole or part, by abutting property lines, exterior building walls or other enclosing devices. "Low-sloped roof" mean roof with a slope of less than 2 units vertical in 12 units horizontal (17% slope). "Parapet" means a barrier that extends upward from the edge of a structure, such as a roof, balcony, walkway, or terrace. "Shaft" means a continuous vertical space substantially enclosed on all sides that extends for 2 or more floors, including, but not limited to, an elevator shaft, a ventilation shaft, a stairwell, or a service shaft.