Accessory Structures in McLean County, IL (2026)
3 rules for unincorporated McLean County, Illinois.
Verified from official government sources
ADU Rules
McLean County's zoning ordinance allows one guest household unit, a secondary living space with its own kitchen, as an accessory use on a residential lot. Section 350-43A(3)(e) caps it at 900 square feet, requires it inside the same building as the main home, and controls where any separate entrance can face.
McLean County Guest House / ADU Standards
Some RestrictionsMcLean County Code § 350-43A(3)(e)
One guest household unit is allowed, which may include a kitchen facility that is separate from that of the principal household unit, subject to the following: ... The guest household unit is located within the same building as the principal dwelling unit. The guest household unit should be accessible through the principal dwelling unit entrance. If a separate exterior entrance to the guest hou...
ADU Rental Restrictions
McLean County's guest household unit, the county's accessory dwelling option, cannot be rented out. Section 350-43A(3)(e)[1] restricts occupancy to guests of the family living in the principal home, so renting the unit to a tenant, whether long-term or short-term, falls outside what the zoning ordinance permits.
McLean County Bars Renting Out Guest Units
Heavy RestrictionsMcLean County Code § 350-43A(3)(e)[1]
The guest household unit is used only for the housing of guests of the family residing in the principal dwelling unit and not as a rental unit.
Shed & Carport Rules
Every shed, detached garage or other accessory structure in unincorporated McLean County must meet the operational standards of Zoning Code Section 350-43A(5): it cannot sit in a required exterior setback, cannot exceed the underlying district's height or coverage limits, and must stand at least five feet from any other structure.
McLean County Accessory Structure Standards
Some RestrictionsMcLean County, IL Code of Ordinances § 350-43.A(5)
Accessory use development and operational standards. The following standards shall apply to all accessory uses and structures unless otherwise specifically provided: Exterior setback. No accessory structure shall be located within a required exterior setback. ... Height. No accessory structure shall exceed the maximum height standards of the underlying district unless specifically authorized. ....
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