Accessory Structures in DuPage County, IL (2026)
2 county-level rules, plus city-specific rules for 1 city in DuPage County, Illinois.
Verified from official government sources
ADU Rules
DuPage County allows one accessory dwelling unit per single-family lot, but only as a conditional use capped at 1,000 square feet and gated behind a County Board-approved permit.
DuPage County Accessory Dwelling Unit Rules
Significant RestrictionsDuPage County Code § 37-417.2
An accessory unit may be maintained as part of the principal single-family dwelling as a conditional use in the districts hereinafter indicated. A. Only one (1) accessory dwelling unit may be maintained in a converted dwelling or on a property where there is an existing dwelling unit. B. The total floor area of an accessory dwelling unit shall not exceed one thousand (1,000) square feet.
Shed & Carport Rules
Any shed, garden building, workshop or livestock shelter built in unincorporated DuPage County needs a building permit under Code § 8-112.1, and Sec. 8-315(D) forces it to meet the same detached-garage construction standard: a sealed floor, ground anchoring and manufacturer-spec installation for any prefab kit.
DuPage County Shed and Accessory Building Rules
Some RestrictionsDuPage County Code § 8-315(D)
Accessory Buildings: Accessory buildings such as pool/garden sheds, stables, livestock shelters, cabanas, greenhouses, workshops, and similar uses where no vehicle storage will take place and where doors small enough to prohibit vehicle entry (approximately six feet (6') are installed shall comply with construction requirements for detached garages with the following exceptions:1.Required concr...
Accessory Structures by City in DuPage County
1 cities in DuPage County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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