Wood I-beams serve several practical purposes in the home that cannot be met using steel I-beams or normal wood boards set on their sides. I-beams are constructed to not only resist up-and-down movement, but also the tendency of the wood to warp or bend from side to side. Wood I-beams are best constructed of framing lumber, which has enough surface area to secure each section of the I-beam in place.
Determine which of the three pieces of lumber will be the vertical part of the I-beam, called the web of the beam. In traditional I-beams, this piece is slightly wider than the other two. For instance, you might choose a 2-by-6 piece of lumber for the web while using 2-by-4 lumber for the flanges.
Measure to the centre of the both of the flanges using the measuring tape and draw a line down the middle of each using the pencil. This provides you with the centre point into which to drive the wood screws.
Turn one of the flanges over so that the line you just drew is facing down. Place the other flange on top of the flange on the ground so that you have created an inverted T-shape. Draw two lines on the horizontal board using the vertical board as a guide. This will help you align the web board when the time comes to secure the pieces together. Use the same technique to draw the same lines on the second flange.
Position the board that is to be used as the web upright on the ground, and then place one of the flanges on top of it. Use the lines you drew to centre the web on the flange.
Drive wood screws through the flange and into the web of the I-beam using the centre line as a guide. Drive the screws in at a distance of one foot from one another, and then turn the I-beam over so that you again have an inverted T-shape. Align the second flange on the web of the I-beam and secure it with screws in the same way you secured the other flange.
While wood I-beams can hold a lot of weight, they are still limited to the strength of the wood used. Avoid overloading the beams with excessive weight, such as parking a car or equipment on the upper floor of a two-level barn.