What is C16 Timber? A Comprehensive Guide By Timber Experts  

Understanding what C16 timber is and whether it's right for your project can be confusing, so our timber experts are here to answer all your questions and help simplify the decision-making process. 

What is C16 Timber? 

C16 timber is a type of kiln-dried softwood, typically pine, spruce, or fir, that is used extensively for construction and DIY projects. The "C16" grading refers to its strength class, with the “C” standing for “coniferous”, marking it out as a softwood. C16 timber undergoes a kiln-drying process to reduce its moisture content to around 20%, making it strong, durable, and unlikely to crack or warp. 

What is C16 Timber Best Used For? 

C16 timber is a versatile material that is ideal for various construction and DIY projects due to its strength and affordability. Some common applications include:

• Flooring: C16 beams are suitable for subflooring and joists, providing a solid foundation for different types of floor coverings.
• Roofing: Professionals often use C16 for rafters and roofing supports, ensuring a sturdy and reliable roof structure.
• Framing: C16 is perfect for wall studs, ceiling joists, wall partitions, and other structural framing.
• Decking: It can be used for constructing garden decking, offering durability and resistance to outdoor conditions when treated.
• Fencing: C16 is ideal for building fences and garden structures, combining durability with affordability. 
• Outdoor Structures: It can be used for other outdoor structures such as sheds, pergolas, and more. 

C16 Timber Strength Grading 

Wood strength grading is a process used to evaluate the structural properties of timber, ensuring it meets specific standards for construction use. This grading assesses factors such as density, knots, grain direction, and overall quality. This process ensures consistency, safety, and reliability in timber used for construction and DIY projects. 

There are two main methods: visual grading and machine grading. Visual grading involves a trained inspector examining the timber for visible defects, while machine grading uses advanced technology to test the wood's strength and stiffness. The resulting grade, such as C16 or C24, indicates the timber's suitability for different applications. 

A C16 grading refers to the minimum strength it can take per square millimetre, and all certified C16 timber will be stamped as such. Below are the stress grading requirements for C16 timber decided by the British Standards BS 5268-2: 

 

Strength Class	Measurement	C16
Bending Parallel to Grain	N/mm2	5.3
Tension parallel to Grain	N/mm2	3.2
Compression parallel to Grain	N/mm2	6.8
Compression Perpendicular to Grain	N/mm2	1.7
Shear Parallel to Grain	N/mm2	0.67
Mean Modulus of Elasticity	N/mm2	8800
Minimum Modulus of Elasticity	N/mm2	5800
Characteristic Density	kg/m3	310
Average Density	kg/m3	370

 

Is C16 Timber Treated? 

C16 timber can be treated or untreated, depending on its intended use. Treated C16 timber undergoes a preservative process to protect against rot, insects, and fungal decay, making it suitable for outdoor and damp environments. The treatment involves pressure-treating the wood with chemicals, which works to extend its lifespan and durability. If you plan to use C16 timber for external applications, such as decking, fencing, or garden structures, it needs to be treated. For these structures, we’d also recommend adding extra sealants and protectants to ensure longevity. 

Untreated C16 timber, on the other hand, can work well for indoor projects where exposure to moisture is minimal. However, even in these situations, there are benefits to using treated C16 timber such as preventing erosion by pests and reducing the growth of mould, while some timber can even have fire retardant treatment for added safety. 

Can C16 Timber Be Used Outdoors?

Yes, C16 Timber can be used outdoors as long as it is treated. To ensure it can withstand the elements by being waterproof, rot-resistant, and insect-repellent, the timber will need pre-treatment. You can also consider extra protection if using this wood for exterior projects such as UV-resistant paints and heavy-duty sealants to ensure the durability of your structure. 

What Sizes Does C16 Timber Come In?

C16 Timber comes in a wide range of sizes so you can find the right fit for your specific project. Our popular Sawn Accoya timber comes in C16 and C22 strength grades and sizes:

• 25 x 150mm
• 38 x 200mm
• 50 x 150mm
• 50 x 200mm
• 63 x 125mm
• 63 x 150mm
• 63 x 200mm
• 75 x 100mm

We also offer other C16 graded timber in our softwood selection, as well as custom sizing to suit your exact needs, so please visit one of our depots or contact us to find out more. 

Choosing Between C16 and C24 Timber 

The difference between C16 and C24 timber lies in their strength and subsequent structural performance. Both fall under the softwood classification, with their number grade indicating the timber's suitability for different structural applications.

C16 Timber

• Has a minimum strength of 16 Newtons per square millimetre.
• It is widely used for general construction, including flooring, roofing, and wall framing.
• More cost-effective, making it a popular choice for standard projects where particularly high strength is not as crucial.

C24 Timber

• C24 is the stronger timber, with a higher minimum strength of 24 Newtons per square millimetre.
• It is better for applications requiring greater structural integrity and load-bearing capacity, such as heavy-duty flooring, beams, and joists.
• More expensive due to its superior strength and quality. 

While both C16 and C24 timber are suitable for various construction uses, C24 timber offers higher strength and durability, justifying its higher cost when used in more demanding structural applications. The ideal grading for you will depend on both your project needs and your budget. 

Find the Right Timber For Your Next Project

C16 timber is a versatile material that is perfect for a wide range of applications. Start your next project today and explore our extensive softwood timber selection. 

At Covers Builders Merchants, you can trust in our 175 years of expertise. We believe top-quality products and customer service are the most important thing. Find your nearest Covers depot and experience the difference a family-run business makes.