Timber resilience starts with fit-for-purpose supply

As demand for timber construction develops, supply resilience depends on more than volume alone. Phil O’Leary examines why merchants, distributors and specifiers need better understanding of appearance, structural end product specification availability and fitness for purpose across the timber supply chain.

There is much discussion about increasing the use of timber in construction. This is understandable. Timber has an important role in modern building and there is increasing interest in using more of the available resource effectively. However, the question is not simply whether there is enough timber. It is whether the right timber is available, correctly graded, correctly described and suitable for the intended end use.

For merchants and distributors, this is a practical issue. Customers may ask for timber by size, species, grade, treatment or intended application. Sometimes the specification is clear. Sometimes it is not. The merchant therefore sits at an important point in the supply chain, between forest resource, sawmilling, grading, treatment, stockholding and construction use.

If timber demand increases, this part of the supply chain becomes more important, not less.

Volume is only part of resilience

The UK remains highly dependent on imported timber and panel products. Timber Development UK reported that UK imports of the main timber and panel products totalled 9.1 million m³ in 2025, just over 2% lower than in 2024, with demand weak over the previous four years and 2025 volumes at their lowest for 10 years.[1]

These figures should be read carefully. A reduction in imports does not necessarily mean a resilient domestic market. It may reflect weaker construction demand as much as improved supply security. For merchants, lower overall volume can still sit alongside shortages of particular sections, grades, species or treated products.

In practice, resilience is often tested at product level. Can the required grade or specification be obtained? Is the section size available? Is the timber treated to the correct use class? Is the species suitable? Is the certification and documentation in place? Can the same product be supplied consistently across a project?

These questions matter because timber is not a single generic material. It is a natural material, processed into products that need to use different properties and different limits to achieve required and expected performance. Substitution may be possible in many cases, but only when the implications are understood.

Strength Grading and fitness for purpose

Strength grading is central to structural timber supply. In the UK market, C16 and C24 are the two main strength classes for structural softwood timber. The number refers to characteristic bending strength in N/mm², with other structural properties defined in the relevant strength class standard.[2]

C24 is often treated as the default choice. In some cases this is necessary. In others it may be overspecification. UK-grown softwood is commonly machine graded to C16, and C16 timber is suitable for many general construction applications when specified and used correctly.[2,3]

This is where better understanding is needed. The question should not be: is C24 better than C16? The question should be: what strength class is required for this application, section size, span, loading and service condition? Can C16 be used instead of C24 by changing, for example, increasing timber size and or reducing the span.

If a structural design requires C24, then C24 should be supplied. If C16 is adequate, then specifying C24 by habit can reduce the opportunity to use home-grown timber, narrow the supply base and add unnecessary pressure to imported supply chains.

Merchants cannot resolve this issue alone. Designers, engineers, contractors and clients all have responsibilities. However, merchants and distributors can help by asking the right questions, providing accurate product information and resisting the idea that a higher grade is always the correct and easy answer.

The importance of correct marking and documentation

Strength graded structural timber is not simply timber that looks suitable. It must be graded and supplied in accordance with the relevant requirements for structural use. BS EN 14081 covers strength graded structural timber with rectangular cross-section, including general requirements and machine grading requirements.[4]

For merchants and distributors, this means documentation and traceability are part of demonstrating product performance. The strength class, species or species group, producer identification, grading method and certification route are not administrative details. They are part of the evidence that allows timber to be used safely and appropriately.

The same applies to legality and responsible sourcing. This is not separate from supply resilience. A resilient supply chain is one that can demonstrate where timber has come from, how it has been processed and what it is suitable for.

Where this information is incomplete, uncertainty enters the supply chain. Uncertainty can lead to delays, rejection of material, conservative specification or avoidance of timber altogether.

Merchants as knowledgeable suppliers

In many cases, merchants are the first point of technical contact for builders, smaller contractors and self-builders. They can often asked practical questions: what timber is needed for a deck, a flat roof, a stud wall, a floor joist or an external structure?

These questions are not always simple. The correct answer may depend on span, loading, exposure, treatment, service class, fixing details, moisture risk and required service life. Timber used externally, for example, must be considered differently from timber used internally. Strength grade alone is not enough if durability, treatment and detailing are wrong.

This is why merchants have a gatekeeping role. They do not replace the designer or engineer and must be wary of accidentally becoming the specifier, but they do influence what reaches site. A resilient merchant supply chain needs staff who understand the difference between structural grade, appearance grade, treatment class, species, moisture content and intended use and can ask relevant questions..

It also needs stock systems that describe products accurately. A pack of timber labelled only by size and price does not provide enough information for structural decision-making.

Building a broader supply base

If the UK wants to make better use of its productive timber resource, markets must be able to accept a wider range of suitable products. This includes greater confidence in home-grown C16 where it is appropriate, better communication between sawmills and merchants, and specifications that allow suitable alternatives rather than defaulting unnecessarily to imported material.

The same principle applies to section sizes. Design decisions made early in a project can determine whether locally or regionally available timber can be used. If the specification is fixed around a narrow product expectation, substitution becomes difficult. If the design allows for appropriate grading, section adjustment or alternative product routes, supply options increase.

This does not mean lowering standards. It means specifying by performance and intended use, rather than habit.

A practical supply chain is one in which information flows both ways. Merchants need to know what designers specify and builders require. Designers need to understand what the supply chain can realistically provide. Sawmills and processors need clearer signals about the grades, sections and treatments the market will accept.

Conclusion

Timber supply resilience is often discussed in terms of planting, harvesting and import volumes. These are important, but they are only part of the issue. Resilience also depends on grading capacity, correct specification, product knowledge, documentation and confidence in fitness for purpose.

For merchants and distributors, the opportunity is to move beyond simply holding stock towards helping the market use timber more accurately. This means recognising when specifications should be queried, asking why C24 has been specified where appropriate, ensuring customers understand the available product options and encouraging discussion where a higher grade or alternative product has been requested.

In practice, many purchasing decisions remain price-led, particularly in DIY and smaller projects, making clear product information and merchant advice increasingly important. The timber resource will only be used efficiently if the supply chain can match material to application. That requires practical knowledge, reliable grading by experts and better communication from forest to merchant to site.

Developing a resilient timber supply chain depends not only on the availability of products but also on shared technical understanding. Merchants, distributors and specifiers should look for opportunities to develop their knowledge of timber grading, product specification and fitness for purpose through recognised industry training, including the visual grading and Timber 101 courses delivered by the Filros technical experts via Woodknowledge Wales.

References

[1] Timber Development UK. TDUK Statistics – Full Year 2025 (2026).

[2] Timber Development UK. Timber Topics November 2025: C16 vs C24 timber (2025).

[3] Department for Environment, Food & Rural Affairs. Timber in Construction Roadmap 2025 (2025).

[4] British Standards Institution. BS EN 14081 Timber structures – Strength graded structural timber with rectangular cross-section.