(1)
Except as provided in Sentence (2), a dwelling unit shall be separated from every other space in a building in which noise may be generated by
(a)
a separating assembly and adjoining constructions, which, together, provide an apparent sound transmission class (ASTC) rating not less than 47, or
(b)
a separating assembly that provides a sound transmission class (STC) rating of not less than 50 and adjoining constructions that conform to Article 9.11.1.4.
(2)
Construction separating a dwelling unit from an elevator shaft or a refuse chute shall have an STC rating not less than 55.