By Allan Jeffrey, founder and CEO of Ultra Decking

Familiar and widely available, timber has been a consistent material choice for both residential and commercial external decking. Often specified without much debate, not because it’s the best option, but because it’s what people know.

Material choices in construction have traditionally been slow to change. Proven performance, known installation practices, and supply chain familiarity tend to outweigh incremental improvements delivered by alternatives. But now, the demands of modern construction are forcing the industry to reconsider its generations-long default to timber.

Timber’s weaknesses are well understood. It moves with moisture, degrades under UV exposure, and requires ongoing treatment to remain structurally sound and visually acceptable. Without ongoing maintenance, performance deteriorates and lifespan is limited. Particularly for exposed environments, timber can require replacement within a few years. Alternatives that address these issues are finally making the market sit up and take notice.

Modern composite boards combine recycled wood fibres with high-density polymers to create a product that behaves differently under the same conditions. Typical compositions now include up to 90–95% recycled content, with a mix of reclaimed wood fibre and polyethylene or polypropylene, reducing reliance on virgin materials. The addition of a protective outer layer, typically a polymer shell, has resolved many of the issues associated with earlier composite products, particularly around fading, staining, and surface degradation.

Composite boards don’t warp or split in the same way as timber. Their ability to preserve size and shape simplifies installation and reduces waste. Dimensional tolerances are typically controlled within a few millimetres per board, compared to the natural variation found in timber, which often requires on-site grading and adjustment. They are also engineered to carry consistent loads across the surface when installed correctly, rather than relying on the natural strength variability of timber, which can differ from board to board. Over time, they maintain a more stable surface, avoiding the uneven wear patterns that develop in natural wood. Surface performance is also more predictable, with slip resistance designed into the board rather than dependent on how the material weathers over time, particularly important in high-traffic or exposed environments.

Unlike timber, composite decking is designed to operate with minimal ongoing maintenance, and leading composite systems now carry warranties of 20 to 25 years, with resistance to rot, insect damage, and moisture ingress built into the material itself. For commercial settings in particular, the benefit of these features to the cost profile is difficult to ignore.

This is where the conversation is changing. Upfront cost comparisons still tend to favour timber, particularly in projects where budgets are tightly controlled on specification. But those comparisons often exclude the ongoing costs that follow installation. As clients and facilities teams become more involved earlier in the process, those omissions are being challenged.

Sustainability considerations are also driving the shift. Timber is often positioned as the environmentally responsible option, but that position depends heavily on sourcing, treatment, and lifespan. Certification schemes such as FSC and PEFC provide a framework, but they’re not uniformly applied or always transparent across global supply chains.

Composite decking offers a different kind of environmental responsibility. High recycled content is now measurable and verifiable. Many products also meet fire performance classifications such as Euroclass Bfl-s1 or Cfl-s1 for flooring applications, making them suitable for use in higher-risk or regulated environments where untreated timber would require additional treatment or be excluded altogether. More importantly, the absence of ongoing chemical treatment, and the extension of usable lifespan, reduce the negative environmental impact.

The residential market has already moved in this direction, largely because individual buyers make decisions based on long-term ownership rather than initial cost alone. The commercial market has been slower to follow, but the same pressures are beginning to apply. Maintenance budgets, sustainability targets, and lifecycle performance are being considered earlier and more rigorously.

Timber will always have a place, particularly where material authenticity or specific design requirements take precedence. But those cases are increasingly proving to be the exception rather than the rule. It is not just the material spec that is changing, but the reasons underpinning that spec.

Decisions once made almost by default are being reassessed against increasingly exacting performance, green and lifecycle cost criteria and, in that context, timber is no longer the obvious choice.