Treated Timber Joist 47 x 175mm C24 (7x2)

Treated Timber Joist 47 x 175mm C24

Ideal for customers looking for dependable timber material, Treated Timber Joist 47 x 175mm C24 (7x2) combines practical performance with straightforward use, while our wider timber wood selection covers a variety of complementary project needs. Treated Timber Joists are a high-performance, reliable choice for structural construction work, offering strength, stability, and versatility. Commonly referred to as softwood carcassing timber, these joists are graded to C24, meaning they meet the highest structural standards and are suitable for load-bearing applications in both domestic and commercial builds. Each joist is pressure treated to enhance its resistance against moisture, fungal decay, and insect attack — making it suitable for above-ground use where occasional wetting may occur. The timber is also planed and regularised, providing smooth, consistent section sizes with eased edges for easy handling and a professional finish. These joists are kiln-dried to reduce moisture content and prevent warping or twisting, ensuring long-term stability and strength. Available in lengths ranging from 3.0m to 6.0m, they’re ideal for floors, walls, roofs, and general carcassing applications. With a PEFC 70% certification, this timber is responsibly sourced, ensuring sustainable forest management while maintaining exceptional quality.

Key Specifications

• Section Size: 47 x 175mm
• Finished Size (Approx.): 45 x 170mm
• Lengths Available: 3.0m, 3.6m, 4.2m, 4.8m, 6.0m
• Grade: C24 (Structural)
• Treatment: Pressure Treated for durability
• Finish: Planed and Regularised with Eased Edges
• Moisture Content: Kiln Dried for improved stability
• Certification: 70% PEFC Certified

FAQs

What does the C24 grade mean for timber joists?

C24 is a high structural grade that signifies superior strength and quality. It’s ideal for load-bearing applications such as floors, roofs, and walls, offering better stability and fewer natural defects than lower grades like C16.

Can treated timber joists be used outdoors?

Yes, C24 treated timber is suitable for external use where there’s an occasional risk of wetting. However, for timber in direct ground contact or constantly wet environments, a higher treatment specification is recommended.

Why is kiln drying important for structural timber?

Kiln drying lowers the timber’s moisture content, making it more stable and less prone to warping, cracking, or twisting. It also ensures the preservative treatment penetrates more effectively, extending the timber’s lifespan and reliability.

Check out our other products here.

Explore more from our range here.

At JJ Building Materials, we're committed to supplying quality building products at competitive prices, backed by the service and expertise you'd expect from an established independent merchant. Whether you're a trade professional managing large-scale projects or a homeowner taking on a DIY renovation, we're here to help you find the right products for the job.

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.

We work with many of the industry's leading manufacturers to bring you trusted products that meet the highest standards of quality and performance. Our team is passionate about providing excellent customer service, competitive pricing and a straightforward shopping experience from start to finish.

When you shop with JJ Building Materials, you can expect:

• Competitive prices on leading brands and quality products.
• Nationwide delivery across the UK
  
• A constantly expanding range of building and landscaping materials.
  
• Friendly, knowledgeable customer support.
  
• A trusted business backed by the JJ Roofing Supplies Group.
  

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.

We work with trusted manufacturers and specialist delivery partners to ensure your order arrives safely and on time. You'll receive tracking details once your order has been dispatched, and if we need to confirm any delivery details, one of our team will contact you directly to keep everything running smoothly.

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.