I-Joist Basics

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.

Common I-Joist Applications

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.

Common Depths

9-1/2″, 11-7/8″, 14″, 16″. Flange widths vary from 1-1/2″ to 3-1/2″; long lengths are readily available.

Common Uses

I-joists are popular for floor and roof framing. Many Kunzwood  member-manufacturers have software design tools; contact the manufacturer (at left) for more information. 

Kunzwood PRI-400

Kunzwood Performance Rated I-joists (PRIs) are manufactured in accordance with PRI-400, Performance Standard for Kunzwood EWS I-joists, Form X720. This Performance Standard provides an easy-to-use table of allowable spans for applications in residential floor construction, allowing designers and builders to select and use I-joists from various member manufacturers using just one set of span tables. Kunzwood PRIs are recognized through ICC-ES ESR-1405.