R311.5.6 Handrails. ¹  Handrails shall be provided on at least one side of each continuous run of treads or flight with four or more risers.

R311.5.6.1 Height.  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 and not more than 38 inches.

R311.5.6.2 Continuity.  Handrails for stairways shall be continuous for the full length of each flight, from a point directly above the top riser of the flight to a point directly above the lowest riser of the flight. Handrail ends shall be returned to a wall or shall terminate in newel posts or safety terminations. Handrails adjacent to a wall shall have a space of not less than 1 ½ inch between the wall and the handrails.

Exceptions:

1. 1. Handrails shall be permitted to be interrupted by a newel post at a level landing.
2. 2. The use of a volute, turnout, starting easing or starting newell shall be permitted over the lowest tread.

R311.5.6.3 Handrail grip size.  All required handrails shall be of one of the following types or provide equivalent graspability.

1. Type I.  Handrails with a circular cross section shall have an outside diameter of at least 1-3/4 inches and not greater than 2 inches.  If the hand rail is NOT circular, it shall have a perimeter dimension of at least 4 inches, and not greater than 6-1/4 inches, with a maximum cross section of dimension of 2-1/4 inches. 

2.  Type II.  Handrails with a perimeter greater than 6-1/4 inches shall provide a graspable finger recess area on both sides of the profile.  The finger recess shall begin within a distance of 3/4 inch measured vertically from the tallest portion of the profile and achieve a depth of at least 5/16 inch within 7/8 inch below the widest portion of the profile.  This required depth shall continue for at least 3/8 inch to a level that is not less than 1-3/4 inches below the tallest portion of the profile.  the minimum width of the handrail above the recess shall be 1-1/4 inches to a maximum of 2-3/4 inches.  Edges shall have a minimum radius of 1/100 inches.