Peoria, IL Accessory Structures: ADU Rules (2026)

Peoria, Illinois (population approximately 113,150, Peoria County) regulates residential density through Appendix B (Zoning Ordinance) of its City Code of Ordinances. Like most Illinois municipalities, Peoria has not codified 'accessory dwelling unit' (ADU) as an independent use category. In the city's single-family residential districts only one principal dwelling unit is permitted per lot; the Zoning Ordinance allows accessory structures (sheds, detached garages) but those are limited to non-residential uses without separate kitchens or sleeping accommodations as habitable units. To establish a legal second dwelling on a single-family parcel an owner must either (1) show the parcel sits in a two-family (R-2/R-3) or higher-density district that permits the second unit as a principal use, or (2) obtain a use variation or special use permit through the Peoria Zoning Board of Appeals (administered under Appendix B). Illinois has no statewide ADU enabling statute as of 2026 — the General Assembly has not adopted anything analogous to California's SB 9, SB 13, or AB 1033, so authority sits with each home-rule municipality under Article VII Section 6 of the Illinois Constitution and the Illinois Municipal Code (65 ILCS 5/1-2-1). Because Peoria is a home-rule city (over 25,000 population), it has full home-rule authority to adopt or restrict ADU rules; it has chosen to restrict. The Peoria Historic Preservation Commission may impose additional review on Historic District properties. HOA-governed properties face additional architectural review under 765 ILCS 160/.