What term describes the horizontal span or length of a stairway?

• A. Total rise
• B. Total run
• C. Run
• D. Tread length

Answer: (B)

The term that describes the horizontal span or length of a stairway is referred to as the "total run." This is a critical measurement in staircase design, as it represents the entire horizontal distance covered by the staircase, which is essential for determining how much space the staircase will occupy in a given area.

Understanding the total run helps in ensuring the staircase complies with building codes and safety regulations while also being functional for users. It is calculated as the sum of the horizontal lengths of all the individual steps (or treads) in the staircase.

The other terms, while related to the construction and design of stairways, do not describe the horizontal distance. The "total rise" pertains to the vertical distance from the lowest to the highest point of the staircase, while "run" can refer specifically to a single step's horizontal distance. "Tread length" is associated with the depth of each step where a foot lands, but not the overall horizontal length of the staircase itself.