Mo. Rev. Stat. § 64.650

Any county commission which has adopted a zoning plan, as provided herein, shall appoint an officer or shall designate one of the existing officials to enforce the provisions of section 64.510. After the appointment or designation of such officer or official, no building or other structure shall be erected, constructed, reconstructed, enlarged or altered, or repaired in such manner as to prolong the life of the building, nor shall the use of any land be changed without a permit issued by such officer or official.