Mo. Rev. Stat. § 292.520

The chief officer in any city, town or village charged with the enforcement of local building laws, and the director of the inspection section are hereby charged with enforcing the provisions of sections 292.450 to 292.540; provided, that in all cities in this state, where a local building commissioner is provided for by law, such officer shall be charged with the duty of enforcing the provisions of sections 292.450 to 292.540, and in case of his failure, neglect or refusal so to do, the director of the inspection section shall, pursuant to the terms of sections 292.450 to 292.540, enforce the provisions thereof.