N.C. State Building Code
Handrails and Guardrails
315.1 Handrails. Handrails having minimum and maximum heights of 30 inches and 38 inches (762 mm and 965 mm), respectively, measured vertically from the nosing of the treads, shall be provided on at least one side of stairways of four or more risers. Spiral stairways shall have the required handrail located on the outside radius. All required handrails shall be continuous the full length of the stairs. Ends shall be returned or shall terminate in newel posts or safety terminals. Handrails adjacent to a wall shall have a space of not less than 1.5 inches (38 mm) between the wall and the handrail.
1. Handrails shall be permitted to be interrupted by a newel post at a turn.
2. The use of a volute, turnout or starting easing shall be allowed over the lowest tread.
315.2 Handrail grip size. The handgrip portion of the handrails shall not be more than 2⅝ inches in cross-sectional dimension, or the shape shall provide an equivalent gripping surface. The handgrip portion of handrails shall have a smooth surface with no sharp corners.
Exception: Exterior handrails shall not be more than 3.5 inches in cross-sectional
1007.5.1 Stairways having four or more risers above a floor or finished ground level, shall be equipped with handrails located not less than 30 (762 mm) nor more than 38 inches (965 mm) above the leading edge of a tread.
315.3 Guardrail details. Porches, balconies or raised floor surfaces located more than 30 inches (762 mm) above the floor or grade below shall have guardrails not less than 36 inches (914 mm) in height. Open sides of stairs with a total rise of more than 30 inches (762 mm) above the floor or grade below shall have guardrails not less than 30 inches (762 mm) nor more than 38 inches (965 mm) in height measured vertically from the nosing of the treads.
315.4 Guardrail opening limitations. Required guardrails on open sides of stairways, raised floor areas, balconies and porches shall have intermediate rails or ornamental closures which do not allow passage of an object 6 inches (152 mm) or more in diameter. Horizontal spacing between the vertical members in required guardrails shall be a maximum of 4 inches (102 mm) at the nearest point between the members.
Exception: The triangular openings formed by the riser, tread and bottom rail
of a guard at the open side of a stairway may be such a size that a sphere 6 inches
(153 mm) cannot pass through.