Stairways, handrails and guards. Every exterior and
interior flight of stairs having four or more risers, and every open
portion of a stair, landing, balcony, porch, deck, ramp or other walking
surface which is more than 30 inches (762 mm) above the floor or grade
below shall have guards. Handrails shall not be less than 30 inches
(762 mm) nor more than 42 inches (1,067 mm) high, measured vertically
above the nosing of the tread or above the finished floor of the landing
or walking surfaces. Guards shall not be less than 30 inches (762
mm) high above the floor of the landing, balcony, porch, deck, ramp
or other walking surface.