The ABC’s of EWP (Engineered Wood Products)
Wood has been used for thousands of years, since the dawn of the World. It has been valued for its light weight, strength and the ease of processing and shaping. The modern world still finds wood to be an important element for construction and design. Wood ‘feels good’, it is a piece of nature that makes part of your home. As for any product we use, the wood underwent some serious improvements over the years. Today’s manufacturers process wood and produce not only typical ‘sawn’ lumber as we have known for ages, but they also process scrap material and wood waste – that originally could not be used for construction. The trick is to bind various types of wood particles – either scrap material or manufactured parts such as veneers – to make an artificial material, typically referred to as “Engineered Wood Products” or EWP – and give lumber super powers!
These are the most common EWP types:
Plywood – is a panel created by cross-laminating continuous sheets of wood veneer in alternating directions, each layer perpendicular to the next. This cross-orienting gives plywood its strength.
Oriented strand board (OSB) – is a panel created by bonding strands of wood in layers with adhesives. Again, the layers are cross-oriented to improve strength and stiffness.
Glued laminated timber (glulam) – is a structural member, a beam consisting of layers of solid-sawn lumber stacked on top of each other and oriented in a way that eliminates or greatly reduces bending and twisting that typically occurs in solid sawn lumber members (if used individually). Glulams can be shaped in curves or custom shapes.
Laminated veneer lumber (LVL) – is a structural beam made by bonding thin veneers of wood. The veneers are oriented in the direction of the span of the beam.
Cross-Laminated Timber (CLT) – is an areal analog of glulam: it is made of several layers of wood, each layer perpendicular to next – giving the material strength and rigidity.
Parallel strand lumber (PSL) – as the name suggests, it is made of strands of lumber – typically long strands that are bonded with adhesive to create a strong material resistant to shape changes
Laminated strand lumber (LSL) – is material manufactured from wood strands of rather long and thin shape. The strands are pressed together and bonded with adhesive to create strong material.
I-joists and wood I-beams – are wood versions of steel I beams – i.e. they are I shaped structural members – with top and bottom flange and a web connecting the two. I joists are used for floor and roof framing and they use less lumber than solid sawn construction members – while carrying the same load.
Manufacturers and software:
There are many manufacturers in US. The most known are Boise Cascade, LLC and Weyerhaeuser Wood Products. Each company has its own line of products and each develops their own software solutions for engineers.
With a multitude of applications, EWP is used everywhere! What is an unusual way you have seen EWP used?
Martin Horak – Design Professional
Gould Design, Inc.