A stair riser accounts for the vertical distance between one step and the next. The riser element of a set of stairs is generally a plank or board installed vertically at an angle of approximately 90 degrees to the stair risers above and below it. Each individual stair riser is usually no taller than 7.5 inches (19 cm), but as many as needed can be used to span the distance between the bottom of the flight and the top.
It is not likely that stairs would even be recognizable without the addition of the riser, because this key element is what gives stairs their gradual increase in height. Looking at a flight of stairs, the riser is the vertical piece that appears to connect the horizontal treads of each step. While walking up a flight of stairs, a person’s toes point at the stair risers. A stair riser is located at the front edge of each step.
The size of stair risers can vary depending on the total amount of space available, design aesthetic, or personal preference. As a general rule, stair risers should not be less than 4 inches (10 cm) tall, but their height should not exceed 7.5 inches (19 cm). Any heights in between these two guidelines are typically considered acceptable for stair risers because they allow people walking up the stairs to assume a comfortable stride and pace. Stair risers that are too short result in very flat flights of stairs that ascend very slowly and require frequent, short steps. In contrast, stair risers that are too tall create excessively steep flights of stairs that may be difficult to climb or hazardous to descend.
The height of stair risers is essential to consider when constructing a flight of stairs, because that measurement is crucial to figuring out how many stairs are needed. For example, if a contractor decides he or she wants stair risers no taller than 7 inches (17.78 cm), the contractor can use this figure to determine how many stairs need to be built. If the total height from where the stairs will begin to where they will end is 56 inches (142 cm), then the contractor can divide 56 inches (142 cm) by 7 inches (17.78 cm) to determine that he or she will require eight stairs in total.
Another key element of a stair riser is its width. Stair risers are usually not more than 1 inch (2.54 cm) thick. Measurements between 0.5 inch (1.27 cm) and 1 inch (2.54 cm) are generally considered sturdy enough to support weight, but will not be so thick that they protrude too much onto the tread of each stair.