34 Pa. Code § 50.34
Exterior openings in vertical shafts which require a minimum 1-hour fire-resistive rating shall be of incombustible construction with all glazed portions being 1/4 inch wire glass in steel frames when such openings are within 10 feet of any other openings in a vertical or horizontal plane.
34 Pa. Code § 50.34
This section cited in 34 Pa. Code § 51.31 (relating to vertical openings); 34 Pa. Code § 52.31 (relating to vertical openings); 34 Pa. Code § 53.31 (relating to vertical openings); 34 Pa. Code § 54.31 (relating to vertical openings); 34 Pa. Code § 55.31 (relating to vertical openings); 34 Pa. Code § 57.31 (relating to vertical openings); 34 Pa. Code § 58.31 (relating to vertical openings); and 34 Pa. Code § 59.31 (relating to vertical openings).