53 Pa. Stat. § 24934
In addition to the aforesaid entrance and exits on the street, there shall be reserved for service, in case of an emergency, an open court or space on the side not bordering on the street where said building is located, or a corner lot, and on both sides of said building where there is but one frontage on the street. The width of such open court or courts shall not be less than seven feet where the seating capacity is not over one thousand people, above one thousand nor more than eighteen hundred people eight feet in width, and above eighteen hundred people ten feet in width. Said open court or courts shall begin on a line with or near the proscenium wall and shall extend the length of the auditorium proper to or near the wall separating the same from the entrance, lobby or vestibule, and said open court, or a separate and distinct corridor from each open court, shall continue to the street through such superstructure as may be built on the street side of the auditorium, with continuous walls of brick or fireproof materials on each side the entire length of said corridor or corridors, and the ceiling and floors shall be fireproof. Said corridor or corridors shall not be reduced in width except by the thickness of the outer wall, and there shall be no projection in the same, the outer openings to be provided with doors or gates opening toward the street. During the performance the doors or gates in the corridors shall be kept open by proper fastenings, but at other times they may be closed and fastened by movable bolts or locks. The said open courts and corridors shall not be used for storage purposes or for any purposes whatsoever, except for exit and entrance from and to the auditorium and stage, and must be kept free and clear during the performance. The level of said corridors at the front entrance to the building shall not be greater than one step above the level of the sidewalk where they begin at the street entrance, and the entrance of the main front of the building shall not be on a higher level from the sidewalk than four steps, unless approved by the bureau of building inspection. To overcome any difference of level existing between exist from the parquet into courts and the level of the said corridors, gradients shall be employed of not over one foot in ten feet with no perpendicular risers.
53 P.S. § 24934