53 Pa. Stat. § 25004
Every room, in any such tenement-house, shall have at least one window, opening upon a street, or upon the open space provided for in the third section of this act. In any city of the second class in which a zoning ordinance has not been enacted, any window opening into a yard or court shall be at least eight feet distant from the wall or party line opposite to it. Any hall in a tenement-house shall have a window or windows, opening either upon a street, or upon the open space provided for in the third section of this act, and shall have no room or other obstruction at the end, unless sufficient light and ventilation is otherwise provided for said hall, in a manner approved by the superintendent of the bureau of building inspection. Whenever, in the judgment of the superintendent of the bureau of building inspection, it shall be possible to construct such tenement-house without corridors connecting the entrance of several tenements or suites of rooms, the superintendent of the bureau of building inspection may require that such tenement-house be so constructed that it shall contain no such corridors.
53 P.S. § 25004