C24 timber joists are ideal for ensuring strength and stability in outdoor decking or roof rafter installations. At Armstrong Cheshire, we offer high-quality, regularised timber for both DIY and professional use. We stock a variety of sizes, from 4x2 timber (47mm x 100mm) to 9x3 timber (75mm x 225mm).

What is C24 timber?

C24 timber is kiln-dried to reduce moisture and is known for its durability and strength. Compared to lower-graded timber like C16, it offers superior performance. The longer growth period for C24 timber results in tighter growth rings, increasing its density and overall strength.

How can you use C24 timber?

C24 is suitable for a range of DIY projects, offering strength for wider spans and heavier loads. It's a good choice for larger projects, such as decking and structural work.

Popular uses

• Ceiling Joists
• Timber Framing
• Roof Rafters
• Web Joists
• Deck Joists
• Floor Joists

Is C24 environmentally friendly?

Wherever possible, Armstrong Cheshire provides our customers with responsibly sourced timber for DIY or professional projects. All our C24 timber is imported from sustainably managed forests.

Our structural timber has been machined finished to ensure consistency of section size. This means the size will be slightly smaller than the item listed. For example, 47 x 150mm (6x2 timber joists) will finish at a size of 45 x 145mm.

What are the other kinds of carcassing timber?

Carcassing timber is usually installed in structural applications where it is hidden from view. There are three primary grades: C16 timber, C24 timber and part-graded timber.

All graded timbers are kiln-dried and slow-grown to ensure that no more than 20% of moisture remains in the wood. This ensures it remains compliant with current building regulations, which means the strength of the timber will be sufficiently strong enough for the applications for which it will be used.

Is C24 timber better than C16?

Regarding load carrying and strength, C24 outperforms C16, which makes it ideal for the abovementioned applications. However, the type of timber you need depends on the performance requirements for your project. This can vary, so where C16 may be appropriate for the application, C24 may be more suited for another.

The aesthetic of the timber may also be necessary to your project; for example, if you want the boards to remain unvarnished, C24 is the better option. If both panels are suitable for your project, it is helpful to know that C24 boards can either have a smaller deck section or a wider rafter centre, which offers more choice on the finish.

Associated products

We are able to provide a complete range of materials to complete your project. For example, if you're using joists for a flat roof, we supply Furring Strips to give the slight slope that would be needed.