Because of its beauty, strength and ease of construction, Glulam (from "glue laminated") has long been in demand as a building material. Glulam is produced in laminating plants by gluing together layers of sawn lumber to form large timbers that retain the traditional beauty of wood along with increased and engineered strength.
Glulam is typically constructed with laminate layers (called lams), glued together. The required strength and position of each lamination is predetermined through engineering analysis. The tension and compression (outside) lams are made of higher-grade lumber and carry much of the bending load. However, the core lams are equally important as they resist the horizontal shear stresses. Individual lams are formed by cutting kiln-dried lumber into pre-determined thicknesses. For Glulam, the lams are then joined together using thermosetting adhesives. These adhesives undergo irreversible chemical change when first heated under pressure, making them excellent structural bonding agents.
Examples of Glulam include columns and beams to carry loads around large openings, such as garage door headers, roof beams, or where built-up columns are required in wall framing. Glulam is available in a variety of widths, depths and lengths.
Structural Composite Lumber (SCL)
SCL products are well known throughout the construction industry as a rectangular shaped product that has superior strength, stiffness, and consistency. Advancements in technology have given SCL manufacturers the ability to take apart a smaller log, sort the pieces, apply adhesive and reassemble them back together into an engineered product that has enhanced product performance. SCL products have grown in popularity because of the availability of long and wide dimensions without warp.
Types of Structural Composite Lumber
While most people are more familiar with product brand names available in the marketplace, there are several acronyms used to describe structural composite lumber, based on the size and shape of the wood pieces that are glued together:
- Laminated Veneer Lumber (LVL)
- Parallel Strand Lumber (PSL)
- Laminated Strand Lumber (LSL)
- Oriented Strand Lumber (OSL)
SCL members can be installed as floor or roof beams, headers over doors and windows, rimboard around the edge of a foundation, or as studs in wall framing.
Building codes specify that structural components, including engineered wood products such as SCL, must meet specific performance requirements from standard test methods before they can be used. All SCL products are rigorously tested for strength and durability with regular quality assurance tests performed during manufacture.
The many advantages of SCL products have increased their use in construction, even though they are typically more expensive.