To build an outdoor handrail, measure the stairs to determine the number of posts needed, cut and attach the posts to the stairs, and attach a handrail to the posts. Cut the top of each post at an angle before attaching the handrail.
When building a handrail, use wood that is designed for outdoor use, and measure the stairs before purchasing the materials to ensure an adequate number of posts are available. To determine how many posts are needed, measure the stringer beginning at the lowest step, and mark the stringer every 36 inches to indicate the placement of a post. Count the marks to determine the number of posts needed, and add an additional post for the top and bottom of the stairs.
Cut 4-by-4-inch posts to the appropriate length, and cut the top of each post at an angle using an adjustable square and a circular saw. Fasten the posts to the stairs with an 8-inch machine bolt, and secure the machine bolts with a nut placed on the inside of the stringer. To determine the length of the handrail, measure the length from the top post to the bottom post, and add 3 inches to allow for overhang. Drill three 3-inch deck screws into the top of the handrail at each post to secure it.