Des Plaines, IL Accessory Structures: Garage Conversions (2026)

Detached garages in Des Plaines are governed by Zoning Ordinance Section 12-8-1 and the City's official 'Residential Detached Garages' handout. Garage walls must be five feet (5') from property lines and out of any easement; in the R-1 and R-2 Residential Districts a detached garage may be placed on the alley without a setback, while all other zoning districts require a five-foot setback from the alley. The maximum size for a detached garage is 720 square feet. The overall height of an accessory structure cannot exceed 15 feet and cannot be higher than the principal home. The combination of all sheds and garages cannot exceed 50% of the required rear yard. The concrete slab must be a 4-inch minimum, 6-bag mix on at least a 6-inch bed of CA-6 gravel, electric is required in all garages, and all garages must have hard-surface driveways. Garage conversions: the City's accessory-structures handout states that if a structure 'will be attached to the home, you must apply for an Alteration/Remodel (Residential) permit,' so converting a detached garage into attached living space, or finishing a garage into habitable space, requires that remodel permit rather than an accessory-structure permit - and converting a garage into a separate dwelling is not allowed (see ADU rules). Building permits are applied for online through the Customer Self Service portal ('Accessory Structure - Garage (Residential)'), and if an existing garage is demolished a separate demolition permit and removal inspection are required before the new garage permit is issued. Conversions that change occupancy or add habitable space are reviewed under the City's adopted 2021 International Residential Code.