Unsourced material may be challenged and removed. This page was last edited on 15 July 2017, at 13:the upward spiral pdf. Staircase”, “Stairway”, and “Stair” redirect here.
Stairs may be straight, round, or may consist of two or more straight pieces connected at angles. Stairs may change direction, commonly by two straight flights connected at a 90 degree angle landing. Stairs may also return onto themselves with 180 degree angle landings at each end of straight flights forming a vertical stairway commonly used in multistory and highrise buildings. Many variations of geometrical stairs may be formed of circular, elliptical and irregular constructions. Stairs may be a required component of egress from structures and buildings. Stairs are also provided for convenience to access floors, roofs, levels and walking surfaces not accessible by other means. Each step is composed of tread and riser.
The part of the stairway that is stepped on. The tread “depth” is measured from the outer edge of the step to the vertical “riser” between steps. The “width” is measured from one side to the other. The vertical portion between each tread on the stair.