Peoria County, IL Accessory Structures: Shed & Carport Rules (2026)

UDO Sec. 3 sets the size limits for accessory buildings like sheds and storage buildings. On residential lots in the A-1 or A-2 Agricultural Districts of five acres or less, outside platted subdivisions, total accessory building floor area cannot exceed 1,300 square feet plus 300 square feet per acre, with fractional acres rounded to the nearest whole acre; larger A-1 or A-2 parcels over five acres carry no floor-area cap on accessory buildings at all. On lots in platted subdivisions, or in residentially zoned districts generally, total accessory building floor area (attached or detached) cannot exceed the footprint of the principal structure or 1,300 square feet, whichever is less, plus an extra 750 square feet allowed specifically for a private garage; no single accessory building may be larger than the footprint of the principal structure, including any attached garage.

Beyond size, Sec. 4 requires that accessory structures, expressly including detached garages, playhouses, sheds, storage buildings, and swimming pools, meet or exceed the minimum setback requirements of the underlying zoning district unless the UDO provides otherwise; attached garages instead count as part of the principal structure for setback purposes. Appurtenances like decks, patios and porches must also meet the district's accessory-structure setbacks, while smaller attached features like eaves, awnings and chimneys are exempt from setback requirements entirely.