Things You'll Need
3 pieces of wood 2-inch x 4-inch x 8-feet
An I-beam is called such because of the shape of its cross section. You can easily build an I-beam by using timber. I-beams are not only more cost effective than normal beams, but they are also strong enough to serve the same purpose. You can use I-beams to create the support structure for floors and ceilings or use them to construct other handy tools like sawhorses. I-beams consist of one vertical section sandwiched between two horizontal sections. The horizontal sections, known as flanges, help to resist bending force, while the vertical piece, known as the web, resists shear force.
Draw lines on two of the pieces of wood. Mark the center point of their width. Also, draw a line to mark the center length across both the long axes of the third board. Place the web with the marked centerline in a vertical position and apply a generous coating of glue, spreading it evenly. Place one of the flanges over it, keeping the centerlines of both edges aligned.
Drill holes in the flange. Make the holes 12 inches apart, starting 4 inches from the edge. Drive the screws in to attach the first flange to the web. Flip the assembly over and apply a generous coat of glue on the other edge of the web. Place your second flange on the web, maintaining alignment as before. Drill holes and screw the second flange into the web. Your I-beam is ready for use. If you want your beam to be stronger, you can add additional cross braces or diagonal braces.
Double-check that your finished I-beam has dimensions of 4 inches wide by 2 inches deep on each edge of the flanges, and a web height of 8 feet. Ensure that the flanges are attached securely, applying additional glue as needed. Note any additional lumps or crowns in the wood, which should be facing skyward during installation.
If you need to join I-beams together and your web is plywood, you can also use sheets with rabbeted edges that can overlap each other. These sheets make stronger joints between web plates. Without them, you can also make your I-beam stronger by gluing and screwing the sections together, in addition to adding braces.