Practical Engineering: Wood I-Joist Fundamentals

Most contractors that frame residential and light-commercial buildings are now (or soon will be) using wood I-joists. For builders accustomed to the shape and heft of conventional sawn lumber joists, the weight and appearance of a typical wooden I-joist often raises an immediate concern about its ability to handle the load. How could such a thin, lightweight material carry as much as a sawn 2×10 or 2×12? Situations like the one in the photo above seem to defy common sense. How can you possibly remove so much of the I-joist web in the middle of a span? Yet the hole chart for that particular I-joist allows you to. Can you imagine doing that with a sawn joist? However,