34 Pa. Code § 56.52 – Required.

An automatic fire alarm system shall be installed in all facilities.

(1) Detection Devices shall be listed as meeting U. L. 217, 1980 Edition. A minimum of one automatic detection device shall be provided on each floor including basement. One automatic detection device shall be located in a common area such as a hall, corridor, or similar area. A detection device shall be located at the top or bottom of each stair. This device may satisfy the requirement for a minimum of one detection device on each floor. See Diagram A for suggested locations of detection devices.
(2) The top of wall mounted detection devices shall be 4 to 12 inches from the ceiling.
(3) Ceiling mounted detection devices shall be located close to the center of the common area, but in no case closer than 6 inches from the wall.
(4) An automatic detection device shall be located outside each sleeping room or area. See Diagram B for suggested locations of detection devices.
(5) The automatic detection devices shall be interconnected so all alarm devices sound if any is activated.

This section cited in 34 Pa. Code § 49.2 (relating to jurisdiction and effective dates).