For longer spans not able to utilize common 2x dimensional lumber, Pre-Engineered and Pre-Fabricated Wood I-Joists have become the modern choice over solid sawn timber joists. They are lighter and more stable than solid sawn, can span greater distances, and come in longer lengths and depths. I-Joists are commonly made with Laminated-Veneer-Lumber top and bottom flanges and a plywood or OSB web. OSB is used more commonly as it typically has greater shear strength. The most common nominal joist depth range is between 10-16″.
The following is a general span capacity that can be expected:
10″ – 16′
12″ – 19′
14″ – 22′
16″ – 25′
16-24″ – Up to 60′
Because of the longer spans, Wood I-Joists can be more susceptible to vibration, additional bracing or oversized members may be required to reduce this issue.