Pennsylvania Statutes Title 53 P.S. Municipal and Quasi-Municipal Corporations § 25020. Ventilation of other apartments

No room (other than basement rooms, provision for which is made in section two of this amendment)   1 in any tenement house hereafter to be erected or constructed, or altered into a tenement house, shall be leased or occupied for living purposes, unless it contains at least one window having a superficial area of not less than one-tenth of the floor area of the room, which window opens upon a street or alley, or upon a yard or court, having a sectional area of less than one hundred square feet;  and no room shall be so leased or occupied in any now existing tenement house, unless it contains a window of the foregoing dimensions, opening upon a street or alley or upon a yard or court having a sectional area of less than twenty-five square feet;  or unless such room adjoins another room in the same apartment, which other room has such a window, opening upon such a street, alley, yard or court, and between which two adjoining rooms there is a sash-window having at least fifteen square feet of glazed surface, the upper half of which is made to open easily.