34 Pa. Code § 21.40 – Stepladders.

(a) Stepladders over 20 feet in length may not be used.

(b) Stepladders shall have side rails of the following solid cross section or a section which is equivalent in strength; the required thicknesses provide for the cutting of a gain not over 1/8 inch in depth and shall be increased when gains of greater depth are used:

Length of Side Rails (feet)	Thickness (inches)	Depth (inches)
Up to and including 10	25/32	2 3/4
Over 10, up to and including 12	25/32	3
Over 12, up to and including 16	25/32	3 1/4
Over 16, up to and including 20	1	3 1/4

(c) Stepladders shall be so constructed that when they are placed in the open position the front section shall have a minimum slope of 3 1/2 inches and the back section a minimum slope of 2 inches for each 12 inch length of side rail.
(d) Stepladders shall be so constructed that when they are placed in the open position all treads shall be level. Treads shall be in accordance with the requirements of § 21.33 (relating to steps).
(e) Except as specified in § 21.31(b) (relating to general) the minimum width between side rails at the top step, inside to inside, may not be less than 12 inches with a spread of at least one inch for each foot of length of stepladder.
(f) A locking device or spreader to hold the front and back sections in open position shall be a component of each stepladder. This device shall have all sharp points covered or removed to protect the user.
(g) The back section of stepladders, if provided with steps, shall be built with side rails having a thickness not less than that specified for the front section in subsection (b) and the depth of side rails shall be such that the section will not develop a working stress for woods listed in § 21.63 (relating to group three woods) greater than 1,600 pounds per square inch when tested by the formula in § 21.32 (relating to side rails). If not provided with steps, the back section shall be built with side rails and bracing necessary to provide for all probable stresses in the section.