To make wood risers for outdoor stairs, first determine the total rise of the staircase. Measure the staircase's vertical height in inches. Divide that number by 7 inches, or the average rise of steps, in order to find the exact rise of each step. Round the rise down to a whole number in order to determine how many steps are necessary. Cut the stringers and attach them. Cut the risers to fit and secure them to the stringers.
Attach the risers to the stringers using a 2-inch deck screw. Measure the risers to hang 1 1/4 inches over the stringers. Risers serve as the backing of each step and preserve the integrity of the staircase by protecting the stringers from weather damage.
Wood risers must also have treads that overlap the stringers. Install treads after the risers are in place, leaving up to 1/4 inch between treads. If you plan to include a handrail, attach it to the stringer before installing the treads.
When building steps for a tall outdoor structure, you must limit stringers to a maximum of 14 steps due to the maximum size of the board being 16 inches. If you need more, consider dividing the steps into groups of seven or eight and separating them with a landing.