53 Pa. Stat. § 14939
No tenement erected prior to June seventh, one thousand eight hundred and ninety-five, no dwelling converted into a tenement, no two-family dwelling or rooming-house, shall be used for human habitation, unless all public halls are lighted on each floor by a window, or windows, of an approved lighting area, opening directly to the outer air, the upper half of which surface opens fully: Provided, however, That whenever any such public hall cannot reasonably be so lighted and ventilated, translucent glass panels of at least four square feet shall be inserted in the wall or in the doors, or as transoms above the doors, leading to the rooms whose windows open directly to the outer air. Such halls shall have a ventilating skylight of satisfactory area in the top floor, directly over the stairway, and, where such is or may be built in, it shall be an acceptable substitute for windows either leading to the outer air or to rooms that lead to the outer air, on the top floor. No tenement erected since June seventh, one thousand eight hundred and ninety-five, shall be occupied for human habitation, unless the windows in its public halls conform to the requirements of section three of the act of Assembly of June seventh, one thousand eight hundred and ninety-five (Pamphlet Laws, one hundred and seventy-eight), entitled "A supplement to an act, entitled 'An act amending section one of article three of an act, entitled "An act for the better government of cities of the first class in this Commonwealth," approved the first day of June, Anno Domini one thousand eight hundred and eighty-five, regulating the construction, maintenance, and inspection of buildings,' approved the eighth day of June, Anno Domini one thousand eight hundred and ninety-three, regulating the construction, alteration, and ventilation of tenement-houses, and providing for the safety of the inhabitants thereof, and providing penalties for the violation of the same." If, after the foregoing provisions have been complied with, such public halls are not adequately lighted in the daytime, the owner, lessee, or conductor of such house shall keep a proper light burning in the hallways, near the stairs, as may be necessary, from sunrise to sunset.
53 P.S. § 14939