DuPage County, IL Building Setbacks & Zoning: Lot Coverage Limits (2026)

DuPage County's zoning ordinance sets a hard percentage cap on how much of a lot's ground area buildings and structures may cover, and the cap depends on the zoning district and reaches only unincorporated pockets of the county, never Naperville, Wheaton, Downers Grove, Elmhurst, Lombard, Glen Ellyn, Woodridge, Carol Stream or the DuPage portion of Bolingbrook, each of which enforces its own code. In the R-5 general residence district, Sec. 8(B) states the rule expressly notwithstanding the permitted-use list in Sec. 1: single-family detached dwellings are capped at 40 percent lot coverage, two-family and multiple-family dwellings at 50 percent, mobile home parks at 40 percent, and every other permitted or conditional use tops out at 60 percent.

Subsection C layers on an enclosed-building requirement: aside from off-street parking or loading areas, every use in the district must be conducted inside a completely enclosed building. By contrast, the county's R-1 single-family district (Sec. ' A property owner who exceeds the applicable percentage is in violation of the zoning ordinance under Sec. 37-1417: the County's zoning official issues a written notice of violation, and the owner has fourteen days to request an administrative appeal hearing or otherwise comply, including paying a $100 processing fee and applying for any needed permit.

Ignoring the notice exposes the owner to a court-assessed fine of $100 to $500 for every week the violation continues, on top of any court order to remove the excess construction.