Ind. Code § 36-7-9-3

Sec. 3. The legislative body of a municipality or county may adopt this chapter by ordinance. The ordinance must specify the executive department of the unit responsible for the administration of this chapter or establish such a department. However, in a municipality in which a commissioner of buildings was appointed to administer IC 18-5-5 (before its repeal on September 1, 1981), the commissioner of buildings is responsible for the administration of this chapter. The ordinance must also incorporate by reference the definition of "substantial property interest" in this chapter.