Mount Prospect, IL Accessory Structures: Shed & Carport Rules (2026)

Section 14.306 of the Village Code sets the accessory structure rules for every zoning district in the Village of Mount Prospect. No accessory building or structure can be built on a lot before the principal building is under construction. A shed cannot sit in a required front yard, required side yard or exterior side yard unless the chapter provides otherwise. Height is capped at ten feet for an accessory building or structure other than a detached garage or gazebo in the residential and commercial districts, and at twenty feet in the industrial, office research and conservation recreation districts. A detached accessory structure must stand at least three feet from the principal building. Each zoning lot is limited to two accessory structures, and swimming pools and the structures listed as permitted obstructions in section 14.319 do not count toward that total. Roof pitch cannot be lower than three to twelve, with pergolas, arbors and accessory structures in the I-1 Limited Industrial and C-R Conservation Recreation districts exempt.

In residential districts the size cap for a shed, gazebo, pergola, greenhouse or similar structure is the smaller of two percent of the lot area or two hundred square feet. On lots fifty five feet wide or less, the setback is three feet from any interior side or rear lot line. On wider lots it is five feet. No accessory structure can go on a right of way or on a village utility or easement without prior consent from the director of community development. All solid roofed accessory structures count in any Floor Area Ratio calculation, and every accessory structure counts toward maximum lot coverage. In business and industrial districts the setback is six feet from any side or rear lot line, and detached accessory buildings can occupy no more than thirty percent of the area of a required yard.

The use limit is as firm as the size limit. A shed cannot store motor vehicles or serve as office, work or living space. Storage of household items, equipment to maintain the property and small recreational equipment is permitted.