6x3 Timber Treated C24

Understanding 6x3 Treated Timber

75mm x 150mm sawn treated timber, traditionally known by the nominal 6x3 inch measurement, offers significantly more mass and bearing surface than standard 2-inch wide carcassing. These sections are kiln-dried to enhance dimensional stability and are strength-graded to C24 specifications. This ensures a high-density wood with minimal defects, providing the mechanical performance necessary for structural applications that must support substantial permanent loads and resist bowing or twisting.

To ensure long-term integrity, the timber is subjected to a high-pressure preservative treatment process. This forces biocides deep into the wood’s cellular structure, creating a reliable barrier against fungal rot and wood-boring insects. This treatment makes the 75mm x 150mm profile exceptionally durable for "first-fix" structural work, where the framework may be exposed to moisture during the initial phases of a build.

The timber is regularised to a finished size of approximately 72mm x 145mm. This precision machining ensures a uniform profile across all lengths, which is critical for creating level planes in flooring and roofing. The eased edges improve site safety and ergonomics, while the 75mm width provides a generous surface area for fixing floorboards, roof sheets, or internal linings.

Material Range

• Individual 75mm x 150mm Lengths: Heavy-duty structural sections available in 3.6m, 4.8m, and 6m lengths to suit varied framing and joisting spans.
• Bulk 6x3 Timber Packs: Trade-scale 49-length packs designed for high-volume efficiency, providing a consistent supply for large-scale structural installations across all stocked lengths.
  
  

Performance Benefits

• Enhanced Load Bearing: The 75mm width provides superior compression strength and a larger bearing surface for structural connections.
• Superior Durability: Pressure-treated with advanced preservatives to prevent rot and insect damage in both internal and external applications.
• C24 Strength Grading: Offers higher tensile strength and stiffness than standard domestic timber, allowing for more demanding architectural specifications.
• Kiln-Dried Stability: Moisture content is strictly controlled to ensure the timber remains straight and stable after installation.
  
  

Typical Applications

• Primary Floor Joists: Supporting heavy internal flooring loads in residential and commercial buildings.
• Roof Purlins and Rafters: Providing the main horizontal or sloping support for large roof structures.
• Timber Frame Construction: Acting as heavy-duty sole plates or structural studs in load-bearing wall panels.
• External Support Structures: Forming the foundational framework for substantial decking areas, bridges, or pergolas.
• Commercial Joinery: Used in industrial settings where robust timber framing is required for mezzanines or partitioning.
  
  

Specification & Standards

• BS EN 14081-1: Strength graded structural timber with rectangular cross section.
• BS EN 335: Durability of wood and wood-based products - Use classes.
• BS 8417: Preservation of wood – Code of practice for professional installations.
  
  

Related Materials and Construction Uses

These 75mm x 150mm sections are frequently specified as the primary structural skeleton for high-end builds. For projects that demand maximum rigidity and density, these lengths are selected from our premium C24-rated structural timber stock. They are often used in conjunction with other structural timber for joists to create a high-performance system capable of spanning wider distances with minimal deflection.

To maintain the protective barrier of the pressure treatment, any on-site cuts or notches should be treated with an end-grain preservative. These heavy-duty sections should be installed using appropriately sized galvanised hangers and high-tensile wood screws to ensure the structural integrity of the entire assembly.