The engineering that underpins oriented strand board has become so well-known as to be overlooked, I sometimes think. Well, especially when trying to mark student assignments describing or failing to describe the concept!

A surprising number of people seem to overlook the idea that the face layers have their strands aligned at right angles to the strands in the core. This gives excellent stability both in the length and the cross direction. The concept is easy to understand in plywood, and in cross-laminated timber (CLT), where we can see these layers clearly. CLT is only on the edge of the panels sector’s radar, as perhaps are the other laminated lumber products. Are they panels?

For some reason OSB can be seen simply as yet another particleboard-type product. Not so! The lay-up of the strands took great ingenuity. The process to ensure the rapid assembly of the mattress with near perfect alignment of these highly engineered strands being very different to air laying of particles or fibres in other panel systems. The thinness and length of the strands gives a wide area for multiple bonding points and excellent transfer of load within the layers. The result is a structural grade product that rapidly displaced plywood in many markets back in the 1980s.

How exciting then to see a new engineered strand product on the market, which will re-raise the potential of this technology. A strand lumber product to rival CLT in fact.

Lignor has launched three products, one a laminated strand lumber (LST), and another which is plywood faced, but the one I will draw your attention to is the cross-laminated strand timber (CLST) product. Here the three (or five or seven) layers are distinctly visible – good news for students who need to see the concept with their own eyes in order to grasp the engineering.

The key for Lignor lies in the stranding technology. Developed in Australia, it was first demonstrated for eucalyptus – traditionally beset with issues such as shake or cracking during drying. Stranding allows near complete use of the log, or the use of juvenile logs. This has enormous potential in regions with eucalypt plantations. But the recent product launch showed material from aspen grown in North America – indicating high adaptability beyond this into other species, both softwoods and hardwoods.

The second innovation is what interests us in the panels sector – forming large layers of strands that are aligned perpendicularly, to offer the same dimensional stability and structural rigidity that the construction sector seeks for mass timber construction. Perhaps this is the product that will connect the wood-based panels sector to the rapid growth in mass timber structural products.

The aspen CLST product has been tested according to the ANSI/APA PRG 320 (Standard for Performance-Rated Cross Laminated Timber), opening the door to structural applications.

A final benefit of the laminated strand lumber technology is the ability to incorporate treatment agents during strand preparation or lay-up, enabling preservatives or fire retardants to be distributed throughout the panel, unlike other plank based laminated timbers.

This final development may be a timely addition to the discussions about service life, durability and fire performance of mass timber systems. By building a new technology on a now familiar oriented strand system, this development may have solved new challenges for the industry as a whole.