How to Make a Banister for Outside Stairs

Cut two 4-by-4 posts to approximately 40 inches in height. If the surfaces of the stairs for which you want to build the banister extend out over the stringers, the angled wood pieces that supports the steps, measure a 4-by-4 inch hole in both the top and the bottom stair on each side of the staircase that requires a banister. Situate the hole so that one edge of it lines up with the stringer below and cut the hole out by drilling at each corner and then using a jigsaw.

Insert one 4-by-4 post into the hole in the top stair roughly 1 1/2 inches deep. Drill two 1/2-inch pilot holes through the stringer and into the 4-by-4 post so that the holes are approximately 1 inch in from each side and vertically centered, drill 4 1/2-inch hex bolts through each pilot hole to secure the post and repeat the process for the post on the bottom stair. If the steps don’t extend out over the stringer, simply line the post up on the outside of the stringer and drill from the inside of the stringer out toward the post.

Cut 2-by-2-inch wood posts to approximately 36 inches. Line up the posts with the posts that you installed on the top and bottom stair, using 2-by-2 posts per stair with even spacing between the posts. Drive two screws up through the bottom of the stair and into the bottom of each post to secure it to the stair.

Measure from the base of each post on the stairs and cut the top off of each post so that it sits 34 inches above the stair. Measure from the top post to the bottom post and cut a 2-by-4 or 2-by-6 wood board to this length or slightly longer if you would like the banister to extend slightly beyond the posts.

Hold up the piece of wood you cut for the banister next to the posts so that it lines up with the corner of the top post closest to the top of the stairs and the corner of the bottom post closest to the bottom of the stairs. Go down the stairs and mark the top of each post where the board passes it, which should be at an angle. Use a jigsaw to remove the corners of the posts at this angle.

Lay the board you cut for the banister in place on top of the posts. Secure the banister to the posts by driving a screw through the banister and into the top of each post. Paint or stain the completed banister.