66 | Sector Focus: Preservatives & Fire Retardants
LEADING FROM THE FRONT
Paul Cave, sales director at Koppers explains why treated timber is a cornerstone of sustainable construction
The UK government’s drive to decarbonise construction has placed timber at the centre of its sustainability strategy. The expanded Timber in Construction (TiC) Roadmap offers ambition, but words alone are not enough. The real work lies with the timber industry itself – manufacturers, suppliers, and specifiers – working to build public trust, raise awareness, and ensure the timber we use is treated, applied, and maintained correctly.
Timber is a natural, renewable, and low- carbon building material. But if we want it to last a lifetime, it must be protected. That is where timber preservation plays a vital role.
WHY TREATED TIMBER MATTERS Timber, when exposed to the elements, is vulnerable. Moisture, insects, and decay can all shorten its life-span. Treated timber—when correctly specified and maintained—can last for decades, even in challenging conditions. But to achieve this, we must understand the different Use Classes that define where and how timber should be used:
• Use Class 2: For interior use, with minimal moisture exposure.
• Use Class 3: For external use above ground, such as cladding and decking.
Requires preservative treatment to withstand rain and humidity.
• Use Class 4: For timber in direct ground contact or exposed to water, such as fence
posts, landscaping timbers, or structural components. Requires heavy-duty treatment.
Misapplication is a silent risk. Timber for cladding isn’t suitable for ground contact. Visually, however, two treated timbers may appear identical. This is why it’s essential to recognise the treatment level and where it should be used. Once treated timber is cut, drilled, or notched, the exposed areas must be resealed with an appropriate end-grain preservative to prevent decay –another detail that is often overlooked.
IDENTITY, CLARITY, AND TRUST To combat confusion, industry bodies such as the Wood Protection Association (WPA) are working to improve clarity. Initiatives such as identity tags on treated timber help end-users and merchants distinguish between different treatment levels. This traceability is crucial. A timber component that looks robust may not be suitable for its environment unless it carries the correct classification.
INDUSTRY MUST LEAD, NOT FOLLOW While government support for timber is welcome, the responsibility cannot rest solely with policy. The industry must lead from
the front. Manufacturers and suppliers must engage with specifiers, contractors, and the public to raise awareness of high-quality, natural, durable, and sustainable timber products when used correctly. This includes improving training, educating the supply chain, and making it easier for people to select the right product for the job. It means showing not just that timber is sustainable but that it works – and will continue to work and look beautiful for decades to come.
BUILDING A LASTING LEGACY The current political spotlight on sustainability presents a rare opportunity. But unless we act, the momentum will pass. Timber must be more than a good idea. It must be a reliable, proven material embedded in modern construction practices. To do this, the industry must speak with one voice, prioritise product quality, educate at every level, and promote preserved timber as the backbone of long-life timber construction.
If used correctly, timber is one of the most sustainable building materials available. But getting it right takes knowledge, discipline, and a shared commitment to doing things correctly. The future of timber in UK construction isn’t written by government – it’s written by us. ■
Above left: Timber is at the heart of the government’s sustainability strategy Above right: The current political spotlight on sustainability presents a rare opportunity
TTJ | May/June 2025 |
www.ttjonline.com
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