In an industry first, the UK’s three largest sawmillers – BSW Timber, James Jones & Sons, and Glennon Brothers – have joined forces in a landmark collaboration to promote the use of domestically grown and manufactured timber.
Backed by leading trade bodies Confor (Confederation of Forest Industries) and Timber Development UK (TDUK), the initiative is a call to action for a more sustainable, economically sound future for the UK construction sector.
Despite the UK having a world-class sawmilling industry, it is the second-largest net importer of forest products globally, with 80% – worth £9 billion – of its requirements imported annually.
This over-reliance on imported timber not only weakens our domestic industry, but also undermines environmental progress, contributes to unnecessary carbon emissions, and reduces the potential for job creation.
Why C16 Timber is the Smart, UK-Grown Alternative to C24
The assumption that C24 is inherently “better” than C16 remains widespread in UK construction. However, from a structural engineering perspective, this distinction is often overstated. In many routine applications, C16 represents a fully compliant, efficient and rational specification choice when assessed against design requirements rather than nominal strength class alone.
Homegrown timber has been an established and dependable material in UK construction for decades. Mostly strength graded to C16, UK spruce softwood is suitable for wall framing, floor joists, roof structures and other load bearing elements in housing. When designed correctly, C16 timber provides predicable structural performance and is well aligned with modern construction methods, including timber-frame systems and offsite manufacture.
The real story is that C16 offers a high-quality, structural-grade timber grown and graded right here in UK. This means you get stable pricing, reliable quality and service, and a significantly lower carbon footprint—all without compromising on the strength and durability your project needs. It’s time to rethink the C16 vs C24 debate.
Strength classes in context
Structural softwood in the UK is graded in accordance with EN 338, with “C” denoting coniferous species and the grade reflecting characteristic strength values.
Both grades comfortably meet UK building regulations for structural applications. While C24 offers higher strength properties, it’s important to consider the specific requirements of the application, as C16 is often entirely sufficient in many cases. C24 is not a widely available grade from UK-grown timber, the timber must have fewer knots and imperfections, which is why it's often sourced from slower-growing trees in colder climates. As a result, specifying C24 can inadvertently limit the use of UK-grown timber resources.
Real-World Performance of C16 Timber
Theoretical strength values are one thing, but performance on site is what truly matters. C16 timber consistently proves its worth across a wide range of common applications.
Can You Use C16 for Floor Joists?
C16 is commonly used for floor and roof joists in UK house building. While C24 can achieve slightly wider spans or carry heavier loads with the same cross-section, a qualified structural engineer will often specify C16 timber at closer centres or with a slightly larger size to achieve the same performance at a lower cost. For most standard residential floors, C16 is the go-to material.
In many scenarios, choosing C24 where C16 would suffice is a case of over-specifying. Stronger isn't always "better" if the additional strength provides no practical benefit for the specific application. Don't pay for performance you don't need.
Value That Lasts: Stable Prices & Cost Efficiency
Budgeting is a critical part of any building project, and timber costs can have a significant impact. This is where C16 provides a clear advantage.
Because C24 timber is primarily imported from regions like Scandinavia and the Baltics, its price is subject to currency fluctuations, international shipping costs, and supply chain disruptions. This volatility can make accurate project costing a challenge.
In contrast, C16 is grown, sawn, and graded in the UK. This local supply chain provides far more predictable pricing, helping you keep your project on budget. By choosing C16, you avoid wasting money on over-specified materials and benefit from cost stability. In terms of lifespan, a properly treated piece of C16 timber will last just as long as a treated piece of C24 when used in the same application, making it a sound long-term investment.
UK-Grown, Sustainable, and Local
When you choose C16 timber, you're making a choice that benefits more than just your project. Most C16-graded timber in the UK is sourced from fast-growing, sustainably managed forests containing Sitka spruce.
This delivers several key advantages:
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Supports UK Industry: You are supporting the UK's forestry sector and the thousands of jobs it provides in rural communities.
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Lower Carbon Footprint: Sourcing timber locally drastically reduces "wood miles." This cuts down on transport emissions compared to importing C24 from overseas, making C16 a more environmentally friendly option.
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Reliable Quality Standards: UK-grown timber is treated to rigorous UK standards. Whether it is kiln-dried to reduce moisture content or "tanalised" (pressure-treated) with preservatives, you can trust it to be protected against rot and insect attack.
Choosing Between C16 and C24: A Practical Guide
So, how do you decide?
Choose C16 for:
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Most internal stud walls and partitions.
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Floor and roof joists in standard residential projects.
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Projects where cost-effectiveness, price stability and environmental impact are priorities.
Consider C24 only when:
C16 timber delivers the strength, durability, and performance needed for the vast majority of UK construction projects at a more cost-effective and stable price point.
By choosing UK-grown C16, you’re not just making a savvy financial decision; you're also supporting local jobs and reducing your project's environmental impact. Build smart, build efficiently, and build with homegrown timber.