I-joists are strong, lightweight, “I” shaped engineered wood structural members that meet demanding performance standards. I-joists are comprised of top and bottom flanges, which resist bending, united with webs, which provide outstanding shear resistance. The flange material is typically laminated veneer lumber (LVL) or solid sawn lumber, and the web is made with plywood or OSB. The robust combination of structural characteristics results in a versatile, economical framing member that is easy to install in residential and light commercial projects. (https://www.apawood.org/i-joist)
I-joists are used extensively in residential floor and roof framing. They are ideal for long spans, including continuous spans over intermediate supports. Because I-joists are straight and true, it’s easier for builders to avoid crowning and maintain a level framing surface. In addition, wood I-joists are typically stocked and readily available in depths that meet the needs of residential framing. (https://www.apawood.org/i-joist)
PWI-joists are a balanced product and do not have a top or bottom like an unbalanced glulam. However, the web does have pre-punched knock-outs that are closer to one flange. The knock-outs are easier for electricians to use when located near the bottom of the installed joist.
PWLVL billets, originally 48” wide when manufactured, are ripped into narrower widths, typically from 3-1/2” up to 24”, across the 48” wide width. Each piece is the same grade as the original billet. A 1-3/4” x 24” can be ripped to a narrower width, including 18”. The capacity of the new beam would be based on the new size. An 1-3/4” x 18” 2.0E LVL ripped from a 24” beam would have the same design values as one that came straight from the factory in that size. PWLVL cannot, however, be planed or sawn to reduce thickness.