7th Dec 2022 -

If you’re looking to use timber as the frame of a construction, you must choose a kind of timber that’s designed to support load-bearing weights. Carcassing timber is designated due to its strength and durability, making it perfect for a variety of first-fix structural applications within a building project. In this guide from Building Materials Nationwide, we’ll explore the benefits of carcassing timber, look at how it’s produced, and explain some of the popular uses for it within building projects, such as for joists and timber framing. Timber can be a fantastic building material, but to construct sturdy buildings it’s important to use stronger options like carcassing timber to build the frame.

What is Carcassing Timber?

Carcassing timber is used for first-fixing structural components within a building. It can be made from softwoods and hardwoods, with stronger options available for load-bearing applications. Strength grading is therefore important in carcassing timber, ensuring that builders use materials that will support the weight of the structure. As carcassing timber does not need to be seen within a finished construction, it will often be of a lower quality. This means that it can contain knots and have a rougher finish. 

Carcassing timber comes in different strength grades, such as the popular C16 and C24 timber gradings. These will both be produced from softwood trees. A C16 strength grading will be the weaker of the two, with more defects, but will possess a reasonable level of strength still. C16 carcassing timber is graded to be suitable for structural applications, and capable of withstanding the stress of weight. Structural-graded carcassing timber will be identified with a stamp. While there are other grades available, C16 and C24 are the most common designations, as Swedish producers started producing C24-graded timber to compete with the British standard of C16.

Need Quality Carcassing Timber?


    • Ideal for general construction, fencing, garden and leisure timber applications
    • Pressure-treated
    Price from: £4.18 £5.02

    • Ideal for general construction, fencing, garden and leisure timber applications
    • Pressure-treated
    Price from: £11.73 £14.08

    • Ideal for general construction, fencing, garden and leisure timber applications
    • Pressure-treated
    Price from: £9.12 £10.94

View C16 and C24 Timber

What Wood is Used in Carcassing Timber?

The main types of wood used in carcassing timber are either European Redwood or European Whitewood. If it is British the term “homegrown” may be used, and timber from abroad will be referred to by terms like “imported softwood”. As carcassing timber is rarely seen the visual differences are largely unimportant, and strength is consistent throughout.

Is Carcassing Timber Treated or Untreated?

In most cases carcassing timber has been pressure-treated and kiln-dried before being graded. The treatment process will involve applying a mixture of chemicals designed to increase the strength and durability of the timber, aiding strong buildings. This will also protect it from insect attacks. Kiln drying will be used to keep the moisture content of the wood below 20%. This process is designed to reduce wood movement, such as bends and twists, which are often caused by excess moisture within the wood. Again, this helps to aid a strong and long-lasting construction. Treated structural timber will benefit the longevity of a building when used. Untreated carcassing timber is also available for situations where excess dampness will not be a pressing issue.

Sustainable Timner

What is it Used For?

  • Joists: Carcassing timber can be used for suspended ground floor joists, roof joists, or loft joists. They can also be used in flat roof construction.
  • Rafters: Carcassing timber can be used to construct the most popular rafter designs, in addition to roofing battens.
  • Wallplates: A wall plate is used in brick houses, laying atop the brick walls and below the joists of the ceiling.
  • Stud Partitions: Stud partition walls can break up a building into rooms, or be used to apply insulation to solid walls.
  • False Work or Framing: Falsework is a temporary structure used in construction as a support for a permanent structure during production or maintenance.
  • Noggins: Wooden struts fixed within joist or stud frameworks, giving strength and stability.
  • Other Uses: Carcassing timber can also be used to make fencing panels, pallets and other packaging materials.

What Sizes Does Carcassing Timber Come in?

Carcassing timber is available in a wide range of sizes, with the size you need dependent on a few factors, such as the load required and the length you will be using. It’s worth noting that the strength grading of a length of timber will be changed when it is sawn in half. This means that they would need to be regraded, especially if they are being used for a vital load-bearing element within a building.

Carcassing Timber Delivered Across the UK

Building Materials Nationwide sells a huge range of sawn timber products, including carcassing timber. We work with a range of builders and contractors, providing them with everything they could need in a building project. We deliver across the UK, with competitive pricing on all products. Alongside our range of carcassing timber, we stock CLSPSE, and treated timber. We also offer sheet materialsdecking and fencing, and external cladding. We also offer trade accounts for customers who work within the industry. Our trade accounts gain you access to your own dedicated account manager, who’ll be there to talk to you over the phone or email, helping to arrange large or unusual orders. Whatever you need in terms of timber or other building materials, we can source them for you from our wide supply network. We offer fast delivery options, and trade account holders can even apply for 30 days of interest-free credit. You can also sign up for a trade account through our website today.

If you enjoyed this guide, we have a wide range available through our website. For example, you can find out more about timber framed stud walls, or fitting skirting boards.