Definition
A lumber grading designation indicating that the wood meets specific strength and stiffness requirements for load-bearing applications. Structural-grade lumber is graded by certified inspectors using visual or machine stress rating (MSR) methods. In the pallet industry, structural-grade lumber is used for stringers, blocks, and lead boards in heavy-duty pallets where failure under load could cause safety hazards. Structural grading ensures predictable performance under engineering calculations.
Related Terms
Lumber Grade
A classification assigned to lumber based on its quality, strength, and appearance characteristics as determined by standardized grading rules. In the pallet industry, common grades include #1, #2, #3, economy, and pallet grade. Higher grades have fewer defects and greater structural integrity but cost more. Pallet designers select lumber grades based on the required performance, application, and budget for each pallet component.
Dimensional Lumber
Lumber that has been milled to standardized widths and thicknesses, such as 2x4, 1x6, or 4x4 nominal sizes. In the pallet industry, dimensional lumber refers to boards and timbers cut to the specific dimensions required for deck boards, stringers, blocks, and other pallet components. Consistent dimensional accuracy is critical for producing pallets that meet specifications and function reliably in automated handling systems.
Stringer
A continuous, longitudinal solid or notched board that connects and supports the deck boards of a pallet. Stringers are the structural backbone of stringer-style pallets, running the full length of the pallet and providing the framework that holds deck boards in place. Most standard 48x40 pallets use three stringers — two along the outer edges and one down the center.
Rackable Pallet
A pallet specifically designed and rated for use in pallet racking systems, where the pallet spans across two rack beams with its load suspended above the floor. Rackable pallets must have sufficient bending strength to support their rated load without excessive deflection (sagging) across the span. This is the most demanding application for a pallet, and rackable load capacity is always lower than static or dynamic load ratings. Typical rackable capacity for a GMA pallet ranges from 1,500 to 2,500 pounds.
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