McLean County, IL Accessory Structures: ADU Rental Restrictions (2026)

Section 350-43A(3)(e) authorizes one guest household unit as a residential accessory use in unincorporated McLean County, and its first numbered condition, § 350-43A(3)(e)[1], draws the occupancy line explicitly: the unit is used only for housing guests of the family residing in the principal dwelling and not as a rental unit. The ordinance does not carve out an exception for short-term platforms such as Airbnb or Vrbo, nor for a longer lease to an unrelated tenant; the text bars rental use categorically rather than by duration.

That makes the guest household unit fundamentally different from a rental accessory dwelling permitted in some other jurisdictions: in McLean County it functions only as extra space for family and personal guests of whoever lives in the main house, not as an income property. The provision sits among the other guest-unit conditions, including the 900-square-foot size cap and the requirement that the unit share the same building as the principal dwelling in § 350-43A(3)(e)[2] and [4], so a property owner cannot sidestep the rental ban by building a larger or detached unit under this same accessory-use category; those paths are independently blocked.

Renting out a guest household unit converts the accessory use into what the county would treat as an unauthorized second dwelling or short-term rental operating without required approvals, exposing the owner to the zoning enforcement remedies in § 350-22, including injunctive action in Circuit Court to stop the rental and restore compliance with the approved accessory use.