Section R. 400.4409 - VentilationRule 409.
(1) Except for a basement, each habitable room shall have direct outside ventilation by means of windows, louvers, air conditioning, or mechanical ventilation.(2) During fly season, between May 1 and October 31, each door, window, and other opening to the outside which is used for ventilation purposes shall be supplied with standard screens of not less than 16 mesh. Each screen door shall have a self-closing device in working condition and shall swing outward.(3) Where windows or louvers are used for ventilation, the total openable area for each resident-occupied room, other than a bathroom, shall not be less than 3 1/2% of the floor area of the room.Mich. Admin. Code R. 400.4409