How to Build Indoor Stair Railings With Two by Fours

Hold wood posts on the bottom and top stair treads where you plan to install the rail’s posts, and then trace around the board. Remove the board and drill holes at the corners of the outlines you traced.

Insert a jigsaw’s blade into the holes you drilled, and then cut along the outlines you drew. Insert the boards into the hole you cut out. Drill holes through the side of the rails and the stair’s base.

Slide bolts through the holes you drilled, from the side of the stairs. Secure a washer and nut to the end of each of the bolts, under the stairs, and tighten the nuts on the bolts using a socket wrench.

Secure a 2-by-4 board to the top and bottom rails on the stairs using two clamps. Place a level on each of the stair treads, measuring the distance from the stair treads to the rail. Adjust the placement of the 2-by-4 rail on the top post until the distance measures the same for each of the stair treads.

Trace where the bottom of the rail board contacts the top and bottom posts, and then unclamp the 2-by-4 from the posts. Trim the top and bottom posts along the lines you traced, using a handsaw. Place the stair rail on top of the posts, and drive finishing nails through the top of the rail and into the top of the posts.

Cut 2-by-4 boards for the rails to fit on each of the stair treads, using the measurement you took between the stair treads and the rail. Cut the boards at the same angle as the posts you already trimmed, and then slide them into position between the rail and the stair treads.

Drive finishing nails through the top of the rail and into the stair rails, as well as through the underside of the stair treads and into the bottom of the rails.