What is the term for the total horizontal distance in a stairway?

The correct term for the total horizontal distance in a stairway is "run." In stair terminology, the run refers specifically to the horizontal measurement from the front edge of one tread to the front edge of the next tread or, in some contexts, from the beginning of the staircase to the endpoint. This is important for understanding the layout and geometry of stairs, particularly in terms of safety and compliance with building codes, which often dictate certain proportions for rise and run in order to ensure that steps are not too steep nor too shallow, promoting a safe ascent and descent.

In contrast, other terms like rise, flight, and refuge have different meanings in stair construction and design. "Rise" typically refers to the vertical distance between two consecutive treads, providing insight into the height of the staircase. A "flight" is a series of steps between landings, while "refuge" denotes a safe area where people can wait in case of an emergency, such as a fire. Understanding these distinctions helps ensure proper stair design, usage, and compliance with safety standards.