Which of the following statements is true about stair construction?

The statement that the unit rise refers to each stair's height is accurate. In stair construction, the unit rise is a crucial measurement that indicates the vertical distance between the top of one step (riser) and the top of the next. Understanding the unit rise is essential for ensuring that stairs are constructed to be safe and comfortable for users. Stairs must meet building codes that specify the maximum height for risers; thus, knowing the unit rise helps builders maintain consistency throughout the stairway, ensuring that each step is uniform and meets the required standards. This consistency is key for safety and usability, making the construction of stairs predictable and compliant with regulations.

The other statements do not hold true according to standard stair construction practices. For instance, a landing is typically required for safety, especially at turns or after a certain number of risers. The height of each riser, while it can be designed within certain limits, is not adjustable once construction begins, as each riser must conform to the established dimensions. Furthermore, all stairs must have risers to create a structured step; constructing stairs without any risers would result in a ramp rather than a traditional flight of stairs, which would not be safe or functional.