Whether planning new outdoor decking or installing new roof rafters, C24 timber joists are precisely what you need to ensure strength and stability. At Armstrong Cheshire, we sell high-quality, regularised timber suitable for DIY and professional applications. From 4x2 timber in mm (47mm x 100mm) to 9x3 timber (75x225mm) you’ll find every size of wood joists you need right here.

What is C24 timber?

C24 timber joists are kiln-dried to reduce moisture and are highly regarded for their durability and strength. Compared to lower-graded timber like C16, this timber floor joist offers superior properties and performance levels. The structural make-up of C24 timber means it can take almost 50% longer for the wood to grow, producing growth rings. The more growth rings a piece of timber establishes, the greater its density, which increases its overall strength. Wood with tight growth rings ensures that it is of high quality.

How can you use C24 timber?

Because C24 is a higher-grade timber that can be used for a wide variety of DIY projects. Thanks to its strength and durability it can be used for wider spans and heavier loads, which makes it a good choice for any larger projects you may be working on. C24-graded timber products are perfect for things such as:

• 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.