This article explores the diverse types of Engineered Wood Products, their applications, and their advantages. Visual references to product forms and applications highlight how EWPs are reshaping timber construction.
Timber has served as a cornerstone material in construction for centuries, offering strength, versatility, and aesthetic appeal. However, traditional sawn timber poses significant challenges, including size limitations, inherent defects, and variability in performance. Engineered Wood Products (EWPs) have emerged as a groundbreaking solution to these limitations, delivering superior strength, reliability, and adaptability for modern construction needs.
EWPs combine advanced manufacturing techniques with natural wood, resulting in products that offer enhanced performance and greater design flexibility. These materials include laminated veneer lumber (LVL), glued laminated timber (glulam), cross-laminated timber (CLT), I-joists, and more. Engineered to maximize timber’s structural potential, EWPs enable architects and engineers to create more sustainable, innovative, and structurally efficient designs.
This article explores the diverse types of EWPs, their applications, and their advantages. Visual references to product forms and applications highlight how EWPs are reshaping timber construction. From multi-storey buildings to iconic bridges, EWPs are unlocking new possibilities in architecture and engineering.
Types of Engineered Wood Products
There are several types of wood products used in timber frame construction. Those typically encountered in practice are briefly described in the next sections.
Glued Laminated Timber (Glulam)
Glued laminated timber, or glulam, is composed of multiple layers of sawn timber glued together with grains aligned in parallel. This process eliminates many natural defects while enhancing the product’s strength and stiffness. Glulam can be manufactured in straight or curved shapes, making it a versatile choice for structural beams, columns, and arches.
Figure 1 illustrates the versatility of glulam in creating curved structural forms, showcasing its ability to balance strength and aesthetic appeal. Glulam beams can span large distances, making them ideal for open-plan spaces such as auditoriums, sports halls, and bridges.
Laminated Veneer Lumber (LVL)
Laminated veneer lumber (LVL) (Figure 2) is crafted by bonding thin layers of softwood veneers under heat and pressure. With grains running parallel, LVL offers uniform strength and reliability. It is often used in high-load applications, including beams, columns, trusses, and portal frames.
LVL’s dimensional stability and reduced moisture content make it suitable for precision-engineered components. Its ability to resist flexural and axial loads ensures durability in demanding environments, such as commercial and industrial buildings.
Cross-Laminated Timber (CLT)
Cross-laminated timber (CLT) features layers of timber glued at right angles, creating a panel with exceptional strength in multiple directions. This arrangement enhances axial, flexural, and in-plane shear capacities, making CLT suitable for load-bearing walls, floors, and roof slabs.
CLT panels can support multi-storey construction, as shown in Figure 3, which demonstrates its application in tall timber buildings. CLT also offers fire resistance and superior acoustic properties, making it ideal for residential and institutional projects.
I-Joists and Open-Web Joists
I-joists combine timber or LVL flanges with thin webs made of oriented strand board (OSB) or plywood. These joists excel in floor and roof applications, providing lightweight and high-performance solutions.
Open-web joists, depicted in Figure 4, feature timber or metal webs, allowing mechanical and electrical services to pass through. These joists are preferred in projects requiring integrated service zones, such as commercial and residential buildings.
Laminated Strand Lumber (LSL) and Parallel Strand Lumber (PSL)
LSL and PSL are made from long wood strands oriented parallel to the longitudinal axis and bonded with adhesives. Both materials share similar applications with LVL but are less common due to supply chain preferences. LSL and PSL remain suitable for beams, columns, and post-and-beam structures.
Applications of Engineered Wood Products
Engineered Wood Products are used across several applications, including:
Residential and Multi-Storey Buildings
EWPs like CLT and LVL play a pivotal role in constructing multi-storey buildings and modular homes. CLT panels, with their monolithic structure, simplify assembly and enhance thermal performance. LVL beams and columns ensure structural integrity while accommodating modern design aesthetics.
Commercial and Public Spaces
Glulam and LVL are often used to create large-span structures like schools, supermarkets, and sports arenas. Their ability to form curved or straight sections enables designers to achieve functional and visually striking open-plan spaces.
Infrastructure Projects
Iconic bridges and domes rely on glulam’s strength-to-weight ratio. EWPs enable long spans and complex geometries, exemplifying their application in infrastructure projects. Bridges constructed with glulam offer durability, reduced maintenance, and a smaller carbon footprint compared to steel or concrete.
Specialized Architectural Forms
Gridshells and stressed skin panels represent the creative potential of EWPs. Figure 8 showcases a glulam gridshell roof, demonstrating how engineered wood can achieve intricate, high-performance designs. These forms provide both structural integrity and aesthetic innovation.
Advantages of Engineered Wood Products
What are the advantages of engineered wood products?
Enhanced Structural Performance
By eliminating natural defects, EWPs deliver predictable performance and greater strength than traditional sawn timber. Their engineered nature allows for tighter tolerances and consistent dimensions, critical for modern construction standards.
Sustainability
Engineered wood promotes sustainability by utilizing smaller wood sections, recycled materials, and efficient manufacturing processes. Timber’s ability to sequester carbon further enhances its environmental benefits.
Design Flexibility
EWPs allow architects to push the boundaries of design. Products like glulam and CLT enable longer spans, taller buildings, and unique shapes that traditional timber cannot achieve. For instance, curved glulam beams create architectural elegance while supporting heavy loads.
Improved Workability
I-joists and open-web joists facilitate the installation of mechanical and electrical services. Their lightweight design reduces labor and construction time. Dimensional consistency minimizes issues such as uneven floors or nail squeaks.
Fire Resistance
Many EWPs, including CLT and glulam, offer inherent fire resistance due to their charring properties. This ensures structural stability during fire exposure, making them suitable for various building types.
Challenges and Considerations
While EWPs offer numerous benefits, their use demands attention to certain challenges:
Transportation and Handling: Large panels like CLT require careful logistics for delivery and installation.
Moisture Sensitivity: EWPs such as OSB can expand in humid conditions, requiring proper protection during construction.
Cost: Initial costs of EWPs may be higher than traditional timber, but their durability and performance often justify the investment.
Fire Safety Planning: Although EWPs exhibit fire resistance, designs must address fire performance during construction and in-use phases.
Conclusion
Engineered Wood Products represent a paradigm shift in timber construction. By addressing the limitations of traditional timber, EWPs enable architects and engineers to create innovative, sustainable, and structurally efficient designs. Their applications span from residential projects to monumental infrastructure, demonstrating their versatility and value.
With ongoing advancements, EWPs are set to play an even greater role in shaping the future of sustainable building practices, making them indispensable for modern architecture and engineering.
Also See: Cross Laminated Timber Construction – An Introduction
Sources & Citations
- “Engineered Wood Products and an Introduction to Timber Structural Systems,” The Structural Engineer, April 2013, Timber Engineering Notebook No. 2.
- Porteus, J., & Kermani, A. (2008). Structural Timber Design to Eurocode 5. Chichester: John Wiley & Sons.
- UK Timber Frame Association (UKTFA). (2013). Engineered Wood Products Code of Practice. Available at: https://jji-joists.s3.amazonaws.com/EWP-COP.pdf
