Engineered lumber represents one of the most significant innovations in modern wood construction, transforming the way builders and designers approach structural framing. Unlike traditional solid-sawn lumber, engineered wood products are manufactured by bonding together wood strands, veneers, fibres, or other elements with structural adhesives to create members with improved strength, consistency, and dimensional stability. These products allow longer spans, greater design flexibility, and more efficient use of forest resources than conventional lumber. The family of engineered lumber products includes laminated veneer lumber (LVL), parallel strand lumber (PSL), laminated strand lumber (LSL), oriented strand lumber (OSL), glued laminated timber (glulam), and wood I-joists. Understanding the characteristics, applications, and installation requirements of each product is essential for construction professionals seeking to optimise structural performance and material efficiency in modern building projects.
To build on this knowledge, explore our detailed guide on Structural Composite Lumber for more in-depth insights into related framing and construction concepts.
Laminated Veneer Lumber (LVL)
Understanding Laminated Veneer Lumber is a critical component of effective structural framing and construction planning.
Laminated veneer lumber is manufactured by peeling veneers from logs — similar to the process used for plywood — and laminating them together with the grain of each veneer oriented parallel to the length of the member. The veneers are dried, graded, coated with a waterproof structural adhesive (typically phenol-formaldehyde or phenol-resorcinol), laid up in parallel orientation, and cured under heat and pressure in a continuous press or platen press. The resulting product has consistent strength properties throughout the member, with allowable design stresses that are typically two to three times higher than those of equivalent-size solid-sawn lumber. LVL is produced in standard thicknesses of 1-1/2, 1-3/4, 3-1/2, 5-1/4, and 7 inches, in depths from 5-1/2 to 24 inches or more, and in lengths up to 60 feet. The parallel grain orientation provides maximum strength in the long direction, making LVL ideal for applications where high bending or axial loads must be carried over long spans.
The primary application of LVL in residential and light commercial construction is as beams and headers spanning openings in walls, supporting floor and roof loads, and as ridge beams in cathedral ceiling applications. LVL headers at window and door openings provide consistent strength without the need for field fabrication of built-up header assemblies, simplifying construction and reducing labour costs. In floor systems, LVL beams support joists where longer spans or heavier loads exceed the capacity of conventional lumber, often eliminating the need for intermediate columns or bearing walls. The dimensional stability of LVL — its resistance to warping, twisting, and shrinking — makes it particularly valuable in applications where movement could cause problems with finishes, doors, windows, or structural connections. LVL can be cut, drilled, and notched in the field within limits specified by the manufacturer, but field modifications that affect the structural capacity must be reviewed by a qualified engineer. For a comprehensive look at engineered lumber products, see our guide on structural composite lumber.
Design considerations for LVL include proper bearing length at supports, end distance for connections, and the effects of holes or notches on member capacity. LVL must bear on a minimum length at each support, typically 1-1/2 to 3-1/2 inches depending on the load and the bearing material’s compressive strength. Connections must be designed for the higher strength of LVL compared to solid lumber, with bolt spacing, edge distance, and group action factors that account for the product’s homogeneous nature and reduced splitting resistance. The manufacturer’s design values and connection design guidance should always be used for LVL design, as the properties differ from those of solid-sawn lumber and vary between manufacturers. LVL is typically manufactured with a camber — a slight upward curvature — that offsets dead load deflection and provides a level appearance under service loads.
Parallel Strand Lumber (PSL) and Laminated Strand Lumber (LSL)
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Parallel strand lumber is manufactured from long, narrow strands of wood — typically 1/8 to 3/16 inch thick, 3/4 to 1-1/2 inches wide, and up to 8 feet long — that are coated with a waterproof structural adhesive and oriented parallel to the member length before being compressed and cured. The long strands provide high strength and stiffness, with design values comparable to or exceeding those of LVL. PSL is typically produced in large cross-sections, up to 7 by 19 inches or larger, and is commonly used for heavy-duty beam and column applications where high loads, long spans, or architectural exposure require maximum structural performance. The product’s appearance — with the long wood strands visible on the surface — makes it suitable for exposed applications where the natural wood character is desired. PSL is more expensive than LVL and other engineered products, limiting its use to applications where its specific advantages justify the additional cost.
Laminated strand lumber is manufactured by pressing oriented strands of wood — typically 1 to 3 inches long and 0.02 to 0.04 inches thick — together with adhesive under heat and pressure. The strands are oriented primarily along the length of the member but with some random orientation that provides more balanced properties in both the longitudinal and transverse directions compared to LVL or PSL. LSL has lower strength and stiffness than LVL or PSL but offers improved nail-holding capacity, screw-holding capacity, and machinability that make it suitable for applications such as studs, millwork components, and rim board. The more random strand orientation also provides greater dimensional stability in the width and thickness directions, reducing the potential for warping or twisting. LSL studs and plates in wall framing provide straight, stable members that resist the bowing and twisting common with solid-sawn studs, improving the quality of finished walls.
Oriented strand lumber is similar to LSL but with a different strand geometry and orientation process, resulting in a product with somewhat different mechanical properties and applications. OSL is typically used for studs, plates, and other light framing applications where its dimensional stability and consistent quality provide advantages over solid-sawn lumber. Like LSL, OSL provides good fastener-holding capacity and can be sawn, drilled, and nailed with conventional tools. The cost of OSL is generally lower than LVL or PSL but higher than solid-sawn lumber, and its use is most economical when the improved performance and reduced waste justify the premium. For a detailed guide on LVL products specifically, see our article on laminated veneer lumber.
Glued Laminated Timber (Glulam)
Glued laminated timber, commonly known as glulam, is manufactured by bonding together individual dimensional lumber laminations — typically 2×4, 2×6, or 2×8 pieces — with their grain oriented parallel to the member length. The laminations are end-joined using finger joints to create continuous lengths, face-bonded with structural adhesives, and cured under pressure to form a single structural member. Glulam can be manufactured in virtually any size and shape — straight beams, curved arches, tapered sections, and custom profiles — limited only by transportation and handling constraints. The layup of laminations can be customised for each application, with higher-grade lumber placed in the tension and compression zones where stresses are highest and lower-grade lumber used in the lower-stress core zones. This selective placement of materials optimises structural performance while controlling cost.
The design of glulam members follows the provisions of the American Institute of Timber Construction (AITC) standards and the National Design Specification (NDS) for Wood Construction. Design values for glulam depend on the combination symbol assigned to the member, which specifies the grade of lumber used in each lamination position. The most common combinations are designated as 24F (for bending members with a design bending stress of 2,400 psi) or 20F, with the specific combination and appearance grade specified in the project documents. Appearance grades range from Industrial (for concealed applications) through Architectural and Premium (for exposed applications where appearance is important). The camber of glulam beams — typically 1.5 to 2 times the dead load deflection — provides a level appearance under permanent loads and is specified by the designer based on the anticipated dead load and span conditions.
Glulam is used extensively in commercial, institutional, and residential construction for long-span roof beams, floor girders, ridge beams, columns, and architectural structures where exposed wood contributes to the aesthetic character of the space. The ability to manufacture curved members for arches, domes, and other architectural forms makes glulam a unique structural material that combines strength with visual appeal. Connections for glulam members require special attention to the lower strength of wood perpendicular to grain, the effects of moisture content changes on connection performance, and the need for corrosion-resistant fasteners in exterior or high-moisture applications. Split-ring connectors, shear plates, and heavy-duty bolts are common connection systems for glulam, with design values provided in the NDS and manufacturer’s literature. Glulam is also commonly used in combination with steel connection hardware — including concealed brackets, knife plates, and slotted steel inserts — that provide strong, aesthetically clean connections.
Wood I-Joists
Wood I-joists are engineered structural members with an I-shaped cross-section consisting of LVL or solid-sawn lumber flanges (the top and bottom horizontal elements) and OSB or plywood web (the vertical element). The I-shape efficiently concentrates material where it is most effective — in the flanges at the top and bottom of the section where bending stresses are highest — while the web, which carries primarily shear forces, can be made from a thinner, lower-cost material. This efficient use of materials results in a product that is lighter, stronger, and more dimensionally stable than solid-sawn joists of equivalent depth. I-joists are manufactured in depths ranging from 9-1/2 to 24 inches, with flange widths of 1-3/4 to 3-1/2 inches, and can span distances of 20 to 40 feet or more depending on the depth, loading, and spacing conditions.
The advantages of I-joists over solid-sawn joists include longer spans that allow more open floor plans, consistent mechanical properties that simplify design, lighter weight for easier handling and installation, and dimensional stability that reduces problems with floor squeaks, nail pops, and uneven floors. I-joists can span further than solid-sawn joists of the same depth, often eliminating the need for intermediate bearing walls or beams and reducing foundation costs. The OSB web accepts cutouts for plumbing, electrical, and mechanical systems more readily than solid lumber, with pre-marked knockouts or allowable hole patterns provided by the manufacturer. However, Web stiffeners may be required at concentrated loads and bearings to prevent web buckling, and field cutting of flanges is severely limited to avoid compromising the structural capacity. The manufacturer’s installation guide must be followed for all bearing details, blocking requirements, and allowable hole locations to maintain the engineered performance of the system.
I-joist installation requires attention to proper bearing, bridging, and connection details that differ from those for solid-sawn joists. I-joists must bear on a minimum of 1-3/4 inches at end supports and 3-1/2 inches at interior supports, with squash blocks or web stiffeners provided where concentrated loads are applied to the top flange. Bridging — typically provided by pre-manufactured metal bridging or solid blocking at mid-span and at supports — prevents the joists from rolling or twisting under load and distributes concentrated loads to adjacent joists. The ends of I-joists are typically restrained by rim board or blocking that transfers lateral loads to the shear walls below. Cantilevers must be detailed according to the manufacturer’s specifications, with reinforcement at the cantilever support point to resist the high shear and bending stresses at that location. For more on harvesting, processing, and using lumber in construction, see our guide on harvesting and using your own lumber.
Installation and Field Practices
The installation of engineered lumber requires careful handling, proper storage, and adherence to manufacturer-specific installation details that differ from those for solid-sawn lumber. Engineered wood products must be stored off the ground on level blocking, protected from weather with breathable covers that allow air circulation, and kept dry to prevent moisture absorption that can cause swelling, warping, or adhesive degradation. Products should be handled carefully to avoid damage to edges, ends, and surfaces — dropped members may sustain internal damage not visible on the surface but still affecting structural capacity. Cutting of engineered lumber to length can be done with standard woodworking tools, but field notching or drilling of flanges on I-joists and LVL beams is strictly limited to locations and sizes specified by the manufacturer. Large openings for mechanical systems must be located in the web within the allowable zone, with the maximum hole size and minimum spacing between holes determined by the manufacturer’s guidelines.
Fastener selection and installation for engineered lumber follow different rules than for solid-sawn lumber due to the homogeneous nature of the material and the different holding characteristics of laminated products. Nails driven into the edge or face of LVL, PSL, or glulam must meet minimum penetration requirements, typically at least 10 nail diameters into the member. Screws provide superior holding power in engineered products compared to nails, particularly for lateral loads, and are recommended for many applications. Pre-drilling may be required for bolts and lag screws near the edges of LVL and PSL to prevent splitting, with the pre-drill diameter and depth specified by the manufacturer or the NDS. The higher density and glue-line integrity of engineered products means that standard fastener design values from the NDS must be adjusted using manufacturer-specific factors that account for the material’s properties. Factory-primed or factory-finished engineered products are available for exposed applications and should be handled and stored with care to protect the factory-applied coating.
Quality Assurance and Inspection
Additional guidance on Wood Design can help you make more informed decisions throughout your framing and structural project.
Quality assurance for engineered lumber begins with verification that delivered products match the project specifications, including correct product type, size, grade, and manufacturer. Each member should be identified with a permanent stamp or label indicating the manufacturer, product designation, design values, and applicable standards. Products should be inspected for damage during transportation — cracked or broken ends, delaminated veneers or strands, and water damage are cause for rejection. The installation should be inspected to verify that bearing lengths, connection details, blocking, and bridging comply with the manufacturer’s installation guide and the approved shop drawings. Any field modifications — holes, notches, or cuts — must be within the allowable limits specified by the manufacturer, and deviation from those limits requires engineering review.
Engineered lumber offers construction professionals a reliable, consistent, and high-performance alternative to traditional solid-sawn lumber for a wide range of structural applications. The improved strength, longer spans, dimensional stability, and efficient use of wood resources provided by LVL, PSL, LSL, glulam, and I-joists have transformed the way buildings are designed and constructed. As forest resources become increasingly valuable and building performance requirements continue to rise, engineered wood products will play an ever-greater role in sustainable, high-quality construction. Construction professionals who understand the properties, applications, and installation requirements of these products can deliver structures that are stronger, more durable, and more resource-efficient than those built with conventional lumber alone. For more on wood design principles, see our guide on wood design in construction.