Tazewell County, IL Accessory Structures: ADU Rules (2026)

055 permits an accessory dwelling in any residential or agricultural zoning district in unincorporated Tazewell County, subject to nine conditions. The lot's principal use must remain a single-family dwelling, and no more than one accessory dwelling may sit on a lot. The accessory dwelling must be owned by the same person who occupies the habitable principal dwelling, ruling out separate ownership arrangements such as a family member owning the accessory unit while a different owner holds the main house. The accessory dwelling must share the driveway serving the principal dwelling rather than getting its own curb cut.

Size is capped at no more than 50% of the principal dwelling's floor area, with a floor of 350 square feet and a ceiling of 800 square feet, so even a large principal home cannot support an oversized accessory unit. If the accessory dwelling sits inside the principal dwelling and has its own separate entrance, that entrance cannot face any street the lot fronts on, preserving a single-family street appearance. An accessory dwelling may instead be located in an unattached garage for the residents of the principal dwelling, covering the classic garage-apartment scenario.

The unit cannot be rented to non-family members, restricting it to family or owner use only, and a 911 address must be obtained for the accessory dwelling so it can be located by emergency responders. The section traces back to Prior Code 7 TCC 1-5(u) and was last amended by Ordinance LU-21-02, passed March 31, 2021.