(1)
Except as provided in Sentences (2) and (4), residential occupancies shall be separated from all other major occupancies by a fire separation having a fire-resistance rating of not less than 1 h.
(2)
Except as provided in Sentence (3), a major occupancy classified as a residential occupancy, including work units, shall be separated from other major occupancies classified as mercantile or medium hazard industrial occupancies by a fire separation having a fire-resistance rating of not less than 2 h.
(3)
Where not more than two dwelling units or work units are located in a building containing a mercantile occupancy, such mercantile occupancy shall be separated from the dwelling units or work units by a fire separation having not less than 1 h fire-resistance rating.
(4)
The requirement for fire separations between major occupancies in Sentence (1) is waived for the occupancies allowed within work units.