When a C-4 occupancy shares a structure with one or more occupancies, the structure shall be governed in one of the following manners:

1. (1) C-4 occupancies shall be separated from all A-1, A-2, B, C-1, C-3 and C-5 occupancies by fire walls. Each portion thus separated shall be considered a separate building.

2. (2) C-4 occupancies may be separated from A-3, C-2 and D-O occupancies by fire walls and considered separate buildings, or C-4 occupancies may share a building with A-3, C-2 or D-O occupancies as a mixed occupancy when all of the following conditions are met:

   1. (i) The construction type complies with the most restrictive limitations of all divisions occupying the building.
   2. (ii) The building size limitations and story height limitations do not exceed the C-4 requirements.