Mich. Comp. Laws § 125.491
Plumbing fixtures. In all dwellings, plumbing fixtures shall be so arranged and maintained as to prevent the wetting of the supporting or surrounding framework which may cause an insanitary condition. The space beneath such fixtures shall be accessible and shall not be so enclosed as to prevent ventilation sufficient to maintain dry and sanitary conditions. The floor and wall surfaces beneath and adjacent to all plumbing fixtures shall be maintained in a sound and sanitary condition. The health officer, or such other appropriate public official as the mayor may designate, may order plumbing fixtures to be supported by metal brackets, and the space beneath left entirely open, when it is indicated that the woodwork has become damp and insanitary and cannot be properly maintained. Defective and insanitary plumbing fixtures, which cannot be repaired, shall be replaced by approved fixtures.
MCL 125.491