The Argument for I-Joists
New products and increased competition make superior I-joist performance available at solid-lumber prices.
Synopsis: Written by a building scientist, this article explores the benefits of building with I-joists, an engineered alternative to solid sawn lumber. Includes an overview of how I-joists work and how they are best used, as well as a chart comparing the cost of using I-joists vs. solid lumber to frame the floor of a typical 28-ft. by 44-ft. ranch house.
Although Apollo 11 and Woodstock got all the attention, 1969 was also the year Trus Joist Corporation (now Trus Joist MacMillan) unveiled the first wood I-beam. The development of the I-joist was originally driven by performance, not price. High-end contemporary designs were inspired by homeowners who wanted open floor plans, which required long clear spans. I-joists, with their deep plywood webs edged by lumber flanges, were much stronger and stiffer than sawn joists, and they gave designers the free hand they needed to fashion less restrictive loadbearing strategies.
While I-joists offer…