6 Pa. Code § 11.89 – Exit signs.

(a) Signs bearing the word ‘‘EXIT’’ in plain, legible letters shall be placed at exits.
(b) If the exit or way to reach the exit is not immediately visible to the clients, access to exits shall be marked with readily-visible signs indicating the direction of travel.
(c) Exit sign letters shall be at least 6 inches high with the principal strokes of letters not less than 3/4 inch wide.

This section cited in 6 Pa. Code § 11.212 (relating to applicability).