55 Pa. Code § 3800.93 – Handrails and railings.

(a) Each ramp, interior stairway and outside steps exceeding two steps shall have a well secured handrail.
(b) Each porch that has over an 18-inch drop shall have a well-secured railing.

This section cited in 55 Pa. Code § 3800.302 (relating to exceptions for outdoor and mobile programs).