7x2 Timber Joists - Treated & Untreated

Frequently Asked Questions

What is 7x2 Timber Used For?

Our 7x2 Timber is a popular choice of timber for framing applications in walls, floors, and roofs, and as a structural timber due to its C24 strength grading. Its strength and width also make it a perfect choice for building outdoor structures such as decking or outdoor planters, when used with an appropriate treatment and moisture barrier.

What Types of 7x2 Timber Do You Offer?

Our 7x2 timber is a strong, C24 timber graded for structural use, and is available in a range of lengths and optionally pressure treated. Both these timbers are structural timbers suitable for framing and building roof, wall and floor structures, though our pressure treated timber also includes treatment for resistance against pests and rot.

What Does C16 / C24 Stand For?

In the UK, regularised timber is most commonly classified into two grades: C16 or C24. The "C" signifies the wood type, specifically Conifer. The number (24/16) indicates the bend strength - which is based on factors such as imperfections and knots. While C24 is the stronger grade, C16 remains exceptionally strong and is used in numerous wall and roofing applications.

7x2 Timber Dimensions

Though often timber is referred to by its size in inches, 7x2 timber does not measure exactly its equivalent size in mm which is approx 47x175mm. 7x2 timber is how it’s traditionally known and continues to be used as the most common name for it, but as all of our 7x2 timber is regularised - which means it is planed to achieve smooth and regular dimensions along the length of the timber - in reality the timber measures a few mm smaller - closer to 45mm x 170mm. As the difference is so small, rarely if ever does this cause an issue when using the timber for its intended purpose.

Do I Need Treated 7x2 Timber?

Our Treated 7x2 Timber is treated to UC2 for resistance to moisture and pests and can be used in outdoor construction - though timber in direct contact with moisture may need further treatment.

Why Choose 7x2 Timber for Your Project?

Our 7x2 timber (175mm x 50mm) represents the perfect balance of strength and versatility, making it an essential choice for both DIY enthusiasts and trade professionals. Whether you're constructing floor joists, roof rafters, or structural framing, this dimensional lumber provides the load-bearing capacity and dimensional stability your project requires.

Key Benefits:

Structural reliability: Graded to C24 standards for consistent strength across every length
Dimensional accuracy: Precise sizing ensures seamless installation and professional results
Moisture management: Kiln-dried to 18-20% moisture content for enhanced stability
Versatile applications: Suitable for internal framing, external construction, and load-bearing elements

Applications That Showcase 7x2 Timber Excellence

Floor Joists and Structural Support At 400-600mm centres, 7x2 timber creates robust floor systems capable of handling significant loads whilst maintaining deflection within acceptable limits. The dimensional stability of our kiln-dried timber minimises seasonal movement, ensuring your floors remain level and creak-free for years to come.

Roof Construction and Rafters For pitched roof construction, 7x2 timber offers the structural integrity needed to support roof loads whilst accommodating insulation requirements. Its generous cross-section provides excellent fixing capabilities for roof coverings and battening systems, making it a favourite amongst experienced roofers.

Stud Work and Internal Framing Whether you're creating partition walls or extending existing structures, 7x2 timber provides the framework strength essential for stable construction. Its compatibility with standard insulation thicknesses makes it particularly suitable for energy-efficient building designs.

Quality Standards You Can Trust

Every piece of our 7x2 timber undergoes rigorous quality control to ensure it meets British Standards BS EN 14081. Our timber is sourced from responsibly managed forests, carrying FSC certification where available, demonstrating our commitment to sustainable construction practices.

Technical Specifications:

Dimensions: 175mm x 50mm (dressed sizes)
Lengths: Available in 2.4m, 3.0m, 4.2m, 4.8m, and 6.0m lengths
Grade: C24 structural grade as standard
Moisture Content: Kiln-dried to 18-20% for enhanced stability
Species: Scandinavian redwood or British-grown Douglas fir

Expert Advice When You Need It Most

Choosing the right timber specification can seem daunting, but you're never alone with DIY Building Supplies. Our experienced team understands the complexities of modern construction and building regulations. We're here to help you select the appropriate lengths, calculate quantities accurately, and ensure your chosen specification meets both structural requirements and budget constraints.

From determining the correct spacing for floor joists to understanding load calculations for roof rafters, our technical expertise ensures your project proceeds with confidence. We provide detailed guidance on fixing methods, treatment requirements, and compatibility with other building materials.

Ready to Start Your Project?

Our comprehensive 7x2 timber collection combines premium materials from leading UK manufacturers with the expert support you need for project success. With competitive pricing, reliable nationwide delivery, and the backing of our knowledgeable team, you have everything needed to tackle your construction project with confidence.

Contact our team today to discuss your specific requirements. We'll help you select the right lengths and quantities whilst ensuring your chosen specification delivers the performance your project demands. Quality timber, expert advice, and reliable service – that's the DIY Building Supplies difference.