When building stairs, there is always one less what than tread?

When constructing stairs, it is important to understand the relationship between treads and risers. The tread is the horizontal part of the step that you step on, while the riser is the vertical part that connects one tread to the next.

In a staircase, there is typically one less riser than the number of treads because the first step at the bottom doesn't have a riser beneath it. For example, if you have a set of stairs with six treads, you will have five risers. This is necessary for the stairs to function properly and ensure a consistent rise and run, which contributes to the safety and usability of the staircase.

Understanding this relationship is crucial for proper stair construction, as it ensures that the stairs meet building codes and safety standards. It also helps in calculating the total rise and run of the stairs, which is integral to the design process.