How to Build a Wood Joist

Measure along your side beam or rim joist and mark it every 24 inches. Use a rafter square to make the mark vertically across the face of the rim joist. Start from the same end of each beam in order to make the marks parallel with each other.

Install a joist hangar on each mark. Attach one side of the bracket, aligned to the line you made on your rim joist. Attach the side of the hangar closest to the end of the rim joist from which you started your measurements. Drive one 1 5/8-inch treated deck screw through each hole on that side of the bracket using a cordless drill. Leave the remaining side loose to fit the joist.

Measure between the rim joists at the first bracket from the end on both sides. Select joist lumber that is straight and free from cracks and splits. Use a miter saw to cut the joist to fit between your rim joists at 90 degrees for a flat end.

Set the cut joist board into the first pair of brackets. Press up the loose side of the joist hangar to hold the joist snugly in an upright position and drive one screw through each hole in the loose side of the joist hangar. Drive one screw through each hole in the joist hangar into the joist board to complete the joint.

Measure and cut a board for each pair of brackets along the wall and complete the attachment, putting one screw into each hole in each bracket.