Section R. 408.31098a - (C506.2) VestibulesRule 1098a. Section 5.4.3.4 of the standard is amended to reads as follows:
5.4.3.4. Vestibules. Building entrances that separate conditioned space from the exterior shall be protected with an enclosed vestibule, with all doors opening into and out of the vestibule equipped with self-closing devices. Vestibules shall be designed so that in passing through the vestibule it is not necessary for the interior and exterior doors to open at the same time. Interior and exterior doors shall have a minimum distance between them of not less than 7 feet when in the closed positon. The floor area of each vestibule shall not exceed the greater of 50 feet2 or 2% of the gross conditioned floor area for that level of the building. The exterior envelope of conditioned vestibules shall comply with the requirements for a conditioned space. The interior and exterior envelope of unconditioned vestibules shall comply with the requirements for a semiheated space. Exceptions:
1. Doors not intended to be used by the public, such as doors to storage, mechanical, electrical, or equipment rooms.2. Doors opening directly from a sleeping unit or dwelling unit.3. Doors that open directly from a space less than 3,000 feet2 (298 m2) in area.5. Doors used primarily to facilitate shipping, receiving, or material handling.6. Doors with no exterior entrance hardware.7. Doors leading solely to outdoor eating areas.Mich. Admin. Code R. 408.31098a