(1)
Except as provided in Sentence (2), stairs shall have no open risers.
(2)
Open risers are permitted in
(a)
interior and exterior stairs that serve a single dwelling unit or a house with a secondary suite,
(b)
fire escape stairs,
(c)
stairs that are principally used for maintenance,
(d)
stairs that serve service rooms, and
(e)
stairs that serve industrial occupancies other than storage garages.