Mich. Comp. Laws § 125.494
Shafts and courts. In every dwelling where there is a court or shaft of any kind, there shall be at the bottom of every such shaft and court a door giving sufficient access to such shaft or court to enable it to be properly cleaned out: Provided, That where there is already a window giving proper access, it shall be deemed sufficient.
In all multiple dwellings of class "b" not of fireproof construction, or not protected with an approved sprinkler system or an approved and self supervised and properly maintained automatic fire alarm system, exceeding 2 stories in height, and having sleeping accommodations for 50 or more persons in which stairways and shafts are not made to comply with sections 39 and 46, the interior stairs, dumb waiters, elevators, clothes chutes, rubbish and all other inside shafts or openings between the various floors or stories of the building shall be enclosed or cut off with a fire resistive enclosure so as to prevent or restrict the vertical spreading of fire or smoke. All stairway shafts or openings between the cellar or basement and the story above in class "b" multiple dwellings shall be enclosed or cut off in the basement or cellar as mentioned above. Such enclosure shall be made of metal lath and 3/4 of an inch of gypsum or portland cement plaster on wood or metal studs, hollow metal, kalomine or other partitions of equivalent fire resistance. Fixed wire glass panels or wire glass windows in steel or metal covered frames may be placed in such enclosures. All door openings in such enclosures shall be protected with self closing fire doors.
MCL 125.494