The structural covering placed directly over framing members which also serves to transfer loads into an I-joist. Wood structural panel sheathing is commonly sold and installed in 4’ x 8’ sheets.

OSB Sheathing
Oriented Strand Board—Manufactured from waterproof heat-cured adhesives and rectangularly shaped wood strands that are arranged in cross-oriented layers, similar to plywood. This results in a structural engineered wood panel that shares many of the strength and performance characteristics of plywood. Produced in huge, continuous mats, OSB is a solid panel product of consistent quality with no laps, gaps, or voids.
Parallel chord trusses are engineered to allow for the installation of ductwork.
Plywood Sheathing
Plywood—Manufactured from thin sheets of cross-laminated veneer and bonded under heat and pressure with strong adhesives. Plywood is also referred to as a wood structural panel.
Exterior plywood sheathing is fabricated with an overlapping edge to prevent water intrusion into the wall cavity.