Ship ladders are permitted to be used in Group I-3 as a component of a means of egress
to and from control rooms or elevated facility
observation stations not more than 250 square feet (23 m2
) with not more than three occupants and for access to unoccupied roofs.
Ship ladders shall have a minimum tread depth of 5 inches (127 mm). The tread shall be projected such that the total of the tread depth plus the nosing projection is no less than 81/2 inches (216 mm). The maximum riser height shall be 91/2 inches (241 mm).
Handrails shall be provided on both sides of ship ladders. The minimum clear width at and below the handrails shall be 20 inches (508 mm).