Predictable spans.
Factory-stamped specs.

I-joists are engineered structural members shaped like a capital "I": two horizontal flanges (typically LVL or solid lumber) sandwiching a vertical web (OSB or plywood). They're used as floor joists and roof rafters for spans where dimensional 2x10 or 2x12 lumber would be too short, too wavy, or too heavy. I-joists run lighter, straighter, and longer than dimensional lumber, with predictable performance under engineered span tables. Midway Supply stocks Roseburg RFPI and onCENTER BLI I-joists.

LVL (laminated veneer lumber) is made by gluing thin wood veneers in parallel, strong in one direction, used for headers, beams, and rim board. PSL (parallel strand lumber, brand name Parallam) is made from long strands of veneer aligned and bonded, stronger and used for high-load posts and beams. Glulam (glue-laminated timber) is built from solid lumber boards stacked and glued, used for long-span beams and decorative exposed-architectural applications. All three are factory-stamped with engineering values. Midway stocks Roseburg RigidLam and onCENTER LVL, with PSL and glulam beams quoted on order.

Engineered wood wins when the span is too long, the load is too heavy, or the available dimensional sizes can't hit the load table. A typical use case: a 16-foot floor span needs an LVL beam where a single 2x12 would deflect too much. Engineered components also stay straight and dimensionally stable across humidity changes, so they're preferred where finish work matters. The makers publish the reason: they are made dry, so they do not shrink, twist, or crown, and the floor tables are figured a third stiffer than code. Midway coordinates engineered components alongside dimensional lumber on the same delivery.

Rim board is the framing member that closes the end of a floor system, running perpendicular to the floor joists at the perimeter of the building. It transfers vertical loads from the wall above down to the foundation or wall below, and it provides the nailing surface for sheathing and band insulation. Standard rim board is engineered LSL (laminated strand lumber) or LVL, dimensionally stable and matched to I-joist depths. Midway stocks Roseburg and onCENTER rim board in common I-joist depths.

I-joist flanges should never be cut or notched. They carry the bending load. The web (the vertical OSB or plywood center) can have holes drilled within manufacturer-specified zones, sized and located per the engineered hole charts that ship with the product. Cutting outside the allowed zones voids the engineering and can cause failure. Each manufacturer publishes hole charts that Midway provides with the order so the framer or plumber knows what's allowed.

OSB (oriented strand board) is engineered wood made from rectangular wood strands oriented in alternating layers and bonded with resin under heat and pressure. Plywood is made from thin wood veneers cross-laminated. OSB is denser and more consistent panel-to-panel. Plywood handles wet exposure better and is preferred for sub-floor and roof sheathing where edge swelling matters. Both are structural-rated; OSB has largely replaced plywood for wall sheathing in residential construction. Midway stocks both.