IRC Definition For Handrail on a Deck or Similar Structure
HANDRAILS Section R311.5.6 2003 IRC
Handrails shall be provided on at least one side of each continuous run of treads or flight with four or more risers.
Handrail height, measured vertically from the sloped plane adjoining the tread nosing, or finish surface of ramp slope, shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm).
Handrails for stairways shall be continuous for the full length of the flight, from a point directly above the top riser of the flight to a point directly above lowest riser of the flight. Handrail ends shall be returned or shall terminate in newel posts or safety terminals. Handrails adjacent to a wall shall have a space not less than 1-1/2 inch (38 mm) between the wall and the handrails.
1. Handrails shall be permitted to be interrupted by a newel post at the turn. A change in direction for a winder stair is not considered as a turn.
2. The use of a volute, turnout, starting easing or starting newel shall be allowed over the lowest tread.
R3184.108.40.206 Handrail grip size.
All required handrails shall be of one of the following types or provide equivalent graspability.
1. Type I.
Handrails with circular cross section shall have an outside diameter of at least 1 ¼ inches (32 mm) and not greater than 2 inches (51 mm). If the handrail is not circular it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6 ¼ inches (160 mm) with a maximum cross section of dimension of 2 ¼ inches (57 mm).
2. Type II.
Handrails with a perimeter greater than 6 ¼ inches (160 mm) shall provide a graspable finer recess area on both sides of the profile. The finger recess shall begin within a distance of ¾ inch (19 mm) measured vertically from the tallest portion of the profile and achieve a depth of at least 5/16 inch (8 mm) within 7/8 inch (22 mm) below the widest portion of the profile. This required depth shall continue for at least 3/8 inches (45 mm) below the tallest portion of the profile. The minimum width of the handrail above the recess shall be 1 ¼ inches (32 mm) to a maximum of 2 ¾ inches (70 mm). Edges shall have a minimum radius of 0.01 inch (0.25 mm).
R3220.127.116.11 Handrails Required.
Handrails shall be provided on the least one side of all ramps exceeding a slope of one unit vertical in 12 units horizontal (8.33-percent slope).
Handrail height, measured above the finished surface of the ramp slope, shall be not less than 34 inches (864 mm) and not more than 38 inches (965 mm).
R318.104.22.168 Handrail grip size.
Handrails on ramps shall comply with Section R322.214.171.124.
Handrails where required on ramps shall be continuous for the full length of the ramp. Handrail ends shall be returned or shall terminate in newel posts or safety terminals. Handrails adjacent to a wall shall have a space of not more than 1.5 inches (38 mm) between the wall and the handrails.