Stairways that have four risers or more must have a handrail between 34 and 38 inches measured vertically from the nosing of the treads.  (The tread is the part of the stair that you walk on, the nose is the edge of the tread).

All required handrails shall be continuous and run the full length of the stairs. Ends shall be returned or terminate into a wall.

The handgrip portion of the handrails shall not be more than 2-1/4 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.

Handrails adjacent to a wall shall have a space of not less than 1-1/2 inches between the wall and the handrail.