47mm x 100mm Sawn Treated Timber C16/C24 (4" x 2") 4.2m

What Is 4x2 Timber 4.2m?

Sawn Treated Timber (4x2) 4.2m is a high-quality, pressure-treated softwood available in primary structural strength grades C16 and C24. Both grades conform to BS EN 14081 and offer reliable performance in a wide range of internal and external load-bearing applications.

Each piece of timber undergoes a rigorous pressure treatment process, forcing preservative agents deep into the wood fibres. This provides robust protection against fungal decay and wood rot, an essential feature in the UK’s damp and variable climate, and also helps deter wood-boring insects that can compromise structural integrity.

While the treatment offers excellent resistance to biological threats, it's important to note that the timber is not fully waterproof and should be sealed or protected as appropriate for exposed applications.

We supply quality 50x100 timber in various lengths: 2.4m, 3m, 3.6m, 4.2m, 4.8m and 6m, all of which are sold in a consistent thickness of 47mm.

Please Note: The finished size of our carcassing timber may vary slightly from the nominal dimensions. You can expect to receive timber that is finished with a thickness 2mm less and a width 5mm less than the nominal measurements stated. Colour and finish are representative only and may vary slightly as this is a natural product.

Applications

Both C16 and C24 timber deliver well in construction projects demanding structural integrity. We recommend using the stronger, more dependable C24 timber grade for larger-scale projects (or in applications where strength is critical, such as balconies, terraces, and bridges).

47x100 treated timber can be used in many different indoor and outdoor applications such as: 

• Structural Framing: A standard choice for constructing internal stud walls and partitions.
• Roofing: Suitable for roof joists and rafters in certain designs and spans (C24 recommended for optimal load-bearing; always consult span tables or structural calculations).
• Flooring: Can be used as floor joists for standard domestic loads.
• Decking Subframes: The pressure treatment provides essential durability for long-lasting decking bases.
• Garden Structures: Excellent for building robust sheds, pergolas, carports, raised beds, and other outdoor projects needing treated timber.
• General Carcassing & Joinery: Ideal  for countless construction and repair tasks.

Benefits 

• Tanalised timber pressure treated with Tanalith 'E' to prevent rot
• Kiln dried to improve stability and straightness
• Strength graded to C16/C24 for known structural performance
• More length options may be available on request

Understanding C16 & C24 

• C16 Grade Timber:
  • Strength: Standard UK structural grade, reliably strong for most common building applications.
  • Appearance: Allows for slightly more knots and potential natural characteristics compared to C24.
  • Common Uses: Internal stud walls, general construction framing, fencing rails, standard decking subframes.
• C24 Grade Timber:
  • Strength: Structural grade, offering increased strength, stiffness, and load-bearing capacity due to stricter grading rules (fewer/smaller knots, tighter grain).
  • Appearance: Presents a 'cleaner' look with fewer visible knots or defects.
  • Common Uses: Roof joists, floor joists, applications requiring wider spans or supporting heavier loads, high-specification decking subframes. 

C24 Grade Timber Availability: If your project specifically requires C24 graded timber, please contact our customer service team prior to ordering to confirm availability and ensure your requirements are met.