Mich. Comp. Laws § 125.480: Storage of combustible materials.

Sec. 80.

Combustible materials and storage spaces. No dwelling, nor any part thereof, nor of the lot upon which it is situated, shall be used as a place of storage, keeping or handling of any article dangerous or detrimental to life or health; nor of any combustible article, except under such conditions as may be prescribed by the fire commissioner, or the proper official, under authority of a written permit issued by him. No multiple dwelling nor any part thereof, nor of the lot upon which it is situated, shall be used as a place of storage, keeping or handling of feed, hay, straw, cotton, paper stock, feathers or rags.

All of the provisions of section 49, except the window requirement, prescribing the protection and construction of spaces used for storage purposes in buildings hereafter erected shall apply to all spaces used for such storage purposes in all existing buildings housing more than 8 apartments if of class "a" or 40 sleeping rooms if of class "b". Where a required window cannot be provided, there shall be a siamese fire department connection.