Treated Timber Joist 47 x 125mm C24 (5x2)

Treated Timber Joist 47 x 125mm C24

As a versatile timber material option, Treated Timber Joist 47 x 125mm C24 (5x2) is well suited to projects where dependable performance and a quality finish are important, while our wider timber wood range makes it easy to source complementary products for the job. Treated Timber Joists provide a strong, durable, and versatile solution for a wide range of structural construction needs. Commonly known as softwood carcassing timber, these joists are graded to C24, meaning they deliver excellent strength, stability, and reliability for use in load-bearing applications across residential and commercial projects. Each joist is pressure treated to enhance resistance against moisture, fungal decay, and insect attack, making it suitable for above-ground applications where there’s an occasional risk of wetting. The timber is planed and regularised, resulting in smooth surfaces, consistent section sizes, and eased edges for easy handling and a clean, professional finish. These joists are kiln-dried to achieve a stable moisture content, improving both structural integrity and long-term performance by reducing the likelihood of twisting, warping, or splitting. Available in 3.0m, 3.6m, 4.2m, and 4.8m lengths, they are ideal for roofing, flooring, wall framing, decking frames, and general carcassing. Responsibly sourced and PEFC 70% certified, these joists combine strength, sustainability, and ease of use — a reliable choice for any construction or renovation project.

Key Specifications

• Section Size: 47 x 125mm
• Finished Size (Approx.): 45 x 120mm
• Lengths Available: 3.0m, 3.6m, 4.2m, 4.8m
• Grade: C24 (Structural)
• Treatment: Pressure Treated for protection and longevity
• Finish: Planed and Regularised with Eased Edges
• Moisture Content: Kiln Dried for improved stability
• Certification: 70% PEFC Certified

FAQs

What is C24 timber used for?

C24 timber is a high-strength structural grade commonly used for load-bearing applications such as flooring joists, roof construction, and wall framing. It offers enhanced strength and fewer natural defects compared to lower grades like C16.

Can C24 treated timber be used outside?

Yes, C24 treated timber can be used outdoors where there’s an occasional risk of wetting, such as decking frames or external structural work. However, it should not be used in constant contact with the ground or water unless further treated.

Why are timber joists kiln-dried?

Kiln drying reduces the moisture content of the timber, improving its stability and preventing issues like twisting or cracking. It also ensures the preservative treatment penetrates effectively, extending the timber’s lifespan and maintaining structural reliability.

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As part of the JJ Roofing Supplies Group, we build on decades of experience supplying construction materials across the UK. We've expanded beyond roofing to offer a growing range of building materials, including timber, insulation, landscaping products, plumbing supplies, flooring, doors, bricks, fencing, garden buildings and much more – all available to order online with nationwide delivery.

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Every order is personally reviewed by our experienced team to ensure everything is correct before dispatch. We offer delivery from as little as the next working day on selected products, so please refer to the dark blue Estimated Delivery box above for the expected delivery timeframe for this item.

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Roof Tiles & Fittings:

We recommend ordering an additional 10% of roof tiles to allow for any breakages that may occur during delivery or handling. Roof tiles are naturally fragile, and having a few extra on site helps prevent delays and ensures your roofing project can be completed without interruption.

Multiple Products from the Same Supplier

If you're ordering multiple products from the same supplier, your order will be dispatched together once all items are ready. This means the longest lead time will apply.

If you need part of your order sooner, please call us on 01202 113233. We can arrange a split delivery, although an additional shipping charge will apply.