70 ILCS 1105/26
The board of commissioners of a district whose boundaries encompass 2 or more municipalities may elect to be governed exclusively by the rules and regulations governing the construction and alteration of buildings and structures as adopted by the county board of the county in which the district is located. The election to be governed by the county's rules and regulations shall be made by adopting an ordinance to that effect. Within 30 days of adoption of the ordinance, the district shall notify each affected municipality of its decision to be governed by the county's rules and regulations by providing the municipality with a certified copy of the ordinance. The effective date of the ordinance shall be 60 days after its adoption by the board of commissioners.
70 ILCS 1105/26