It’s almost impossible to not use engineered wood products when looking at all wood-framed buildings. In this article, we want to discuss two particular kinds of manufactured wood products, structural composite lumber (SCL), and glue-laminated (Glulam) timber framing. Professionals in the design world need to understand the key features and differences involved in the various SCL and Glulam framing products.
Structural composite lumber (SCL) is used when discussing the group of manufactured wood that has layered wood veneers that are bonded with moisture-resistant adhesives to make structural supports like beams, studs, or columns. SCLs have many advantages over sawn conventional lumber: higher strengths, dimensional stability, and moisture resistance. SCL is a family of three products primarily: Laminated Strand Lumber (LSL), Parallel Strand Lumber (PSL), and Laminated Veneer Lumber (LVL).
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Consisting of several layers of wood lumber, bonded together with high-strength adhesives, Glulam is a revolutionary, versatile laminated beam used in all kinds of construction, whether it be residential or commercial. A unit looks like a stack of large lumber strongly bonded by glue. Coming in many different sizes, it can be custom-fabricated to meet a great range of design specifications. Due to its durability and sturdiness, it’s often the go-to for use in building high roofs, arches, and tunnel roofs.
When speaking on Glulam connections, they feature steel bolts, dowels, and plates.
Laminated Veneer Lumber (LVL)
LVL is the typical timber wall bonding option for most modern buildings. Commonly referred to as Microlam, LVL is made of thinly sliced veneers laid in a parallel fashion and bonded together through heat and significant pressure. Standard sizes of LVL include widths of 3.5″, 5.25″, 7″, and depths from 9.5″ to 24″ deep. Columns come in sizes of 4×4 and 8×8.
The biggest appeal among builders for using LVL is its cost, it’s very cheap. A particular advantage to this beam type is you can custom fabricate it to match narrower beams. In addition, you can create a larger beam merely by nailing several plies together. This can come in handy when retrofitting projects require lifting a big, heavy beam that can be next to impossible.
Parallel Strand Lumber (PSL)
PSL is manufactured by laying veneers into long parallel strands and then bonding them together. These are primarily used in areas where high strength is required, like beams or header applications. The standard sizes come similarly to LVL, the widths being 3.5”, 5.25”, 7” and depths matching I-Joists from 9.5” to 24” deep. Columns are also available in sizes comparable to sawn wood members of 4×4 to 8×8.
PSL affects the wallet more than Glulam, LSL, or LVL beams; as well as they can be stained or finished in an aesthetically pleasing way.
Laminated Strand Lumber (LSL)
LSL is manufactured from flaked wood strands that can resemble an oriented strand board (OSB), the strands are arranged in a parallel fashion to the longitudinal axis of the member. The members are fabricated in widths of 1.25″, 1.5″, 1.75″, and 3.5″, and their depths are between 9.25″ and 16″ to be able to match the I-Joists. Stud options are available in sizes of 2×4, 2×6, and 2×8 which are stronger, straighter, and longer than the sawn lumber option. LSL is often the least expensive option when compared to other manufactured wood beams.
Because of their shear strength, LSL beams have a larger capacity for penetrations than that other engineered wood beams. The LSL is not quite as strong as LVL or PSL beams but is generally cheaper and better for shorter periods. It is also great to use in rim conditions because of its limited shrinkage, cupping, and high fastener holding strength when being used in high load diaphragms or for shear transfer at plywood shear walls.