C24 vs C16 Timber: What’s the Difference and Which Should You Use?
When it comes to structural timber, one of the most common questions we get asked is:
“What’s the difference between C16 and C24 timber?”
If you're working on a building project and need to choose the right grade of timber, understanding these two classifications is key. In this blog, we break down what C16 and C24 timber grades mean, their differences, and when to use each.
What Does ‘C’ Mean in C16 and C24 Timber?
The ‘C’ stands for conifer, indicating that the timber comes from softwood species like spruce, pine or fir. The numbers – 16 and 24 – relate to the bending strength of the timber (measured in N/mm²). The higher the number, the stronger the timber.
C16 Timber: Reliable and Cost-Effective
C16 timber is the most commonly used structural timber in UK construction. It offers good performance at a budget-friendly price.
Why Choose C16?
- Strength: Suitable for standard load-bearing applications.
- Appearance: May have more knots and natural imperfections.
- Cost: Generally cheaper than C24, making it ideal for large-scale or budget-conscious builds.
- Typical Sources: Often sourced from UK-grown softwoods like spruce.
Common Uses:
- Internal wall studwork
- Roof battens
- Floor joists
- General construction and framing
C24 Timber: Stronger and Higher Quality
C24 is a premium structural grade, offering superior strength and a cleaner appearance. It’s graded more stringently and often sourced from slow-grown Scandinavian timber, which is denser and more robust.
Why Choose C24?
- Strength: Up to 50% stronger than C16 – ideal for long spans or heavy loads.
- Appearance: Fewer knots and defects, making it suitable for visible or decorative applications.
- Durability: Denser grain and higher stability due to slow growth in colder climates.
Common Uses:
- Decking joists and frames
- Roof rafters
- Structural beams
- Exposed timber work
C16 vs C24 Timber: Side-by-Side Comparison
| Feature | C16 Timber | C24 Timber |
| Strength | Standard structural strength | Higher strength and load-bearing capacity |
| Cost | More economical | Slightly more expensive |
| Appearance | More knots and imperfections | Cleaner, better visual quality |
| Best For | General framing and internal use | Long spans, exposed or structural areas |
Which One Should You Choose?
The answer depends on the requirements of your project.
- Choose C16 for general construction where budget is key and the timber won’t be visible.
- Opt for C24 when you need greater strength, longer spans, or a cleaner visual finish – especially for exposed timber elements or external structures like decking.
Need Help Choosing Timber?
At [Your Company Name], we stock a full range of C16 and C24 timber in various sizes – all strength-graded to BS EN 14081 standards.
Not sure which grade is right for your job? Get in touch with our team – we’re here to help you find the perfect timber for your build.
Contact us today or pop into your nearest branch to speak with one of our timber specialists!