53 Pa. Stat. § 24937
When located on a corner lot that portion of the premises bordering on the side street and not required for the uses of the theatre may, if such portion be not more than twenty feet in width, be used for offices, stores or apartments, provided the walls separating this portion from the theatre proper are carried up solidly to and through the roof, and that a fireproof exit is provided from the theatre on each tier equal to the combined width of exits opening on opposite sides in each tier communicating with balconies and staircases leading to the street in a manner provided in this section. Said exit passages shall be entirely cut off by brick walls from said offices, stores or apartments, and the floors and ceilings in each tier shall be fireproof.
53 P.S. § 24937