5x2 Timber Treated
(12 Products)47mm x 125mm treated timber provides a robust structural solution for medium-span floor joists, roof rafters, and heavy-duty framing. Pressure-treated to protect against biological decay and insect infestation, these versatile lengths are essential for load-bearing applications in both internal and external construction environments.
Understanding 5x2 Treated Timber
47mm x 125mm sawn treated timber, frequently specified by its nominal 5x2 inch dimensions, is a core component for structural carcassing in UK building projects. While smaller 4x2 treated timber sections are often used for non-load-bearing partitions, this C24-graded 125mm profile is kiln-dried to improve dimensional stability. The pressure-treatment process involves forcing biocides deep into the wood grain, ensuring the structural integrity of the timber framework remains resistant to fungal decay and interstitial condensation in damp environments.
The timber is typically supplied with a finished size of approximately 45mm x 120mm. This planed finish includes eased edges, which facilitates safer handling on-site and ensures a more precise fit when constructing complex floor or roof assemblies. The increased depth of the 125mm profile compared to smaller sections allows for greater load-bearing capacity and longer spans, making it a preferred choice for residential flooring and flat roof systems.
Available in a comprehensive range of lengths from 2.4m to 6m, this inventory supports efficient material usage and reduces the need for excessive on-site jointing. Whether purchased as individual pieces for bespoke renovations or in high-volume packs for new-build developments, this timber provides a reliable, long-term structural foundation.
Material Range
- Individual 47mm x 125mm Lengths: Versatile pressure-treated sections available in seven distinct lengths from 2.4m to 6m, including 5.4m and 4.2m options for specific span requirements.
- Bulk 5x2 Timber Packs: Large-scale 88-length packs designed for high-volume trade use, providing a consistent supply of treated carcassing for major framing and joisting projects.
Performance Benefits
- Biological Resistance: Deep-penetration pressure treatment protects the core against fungal rot, decay, and wood-boring insects.
- Structural Integrity: Kiln-dried and strength-graded to provide the mechanical performance necessary for permanent load-bearing structures.
- Enhanced Stability: The kiln-drying process reduces moisture content, significantly lowering the risk of twisting, bowing, or splitting after installation.
- Consistent Finish: Planed-all-round with eased edges to ensure uniform dimensions and improved ergonomics during manual handling.
Typical Applications
- Floor Joists: Supporting internal flooring systems in domestic and light commercial buildings. For significantly wider clear spans or increased dead loads, many engineers upgrade to 6x2 timber to maintain stiffness and reduce deflection across the floor diaphragm.
- Roof Rafters: Creating the primary framework for pitched and flat roof structures.
- Decking Substructures: Forming a durable, rot-resistant base for external timber decking and platforms.
- Wall Partitioning: Constructing heavy-duty internal stud walls and load-bearing partitions.
- External Structures: Building robust garden furniture, pergolas, and structural outbuildings.
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 EN 599-1: Durability of wood and wood-based products – Efficacy of preventive wood preservatives.
Related Materials and Construction Uses
These 47mm x 125mm sections are often utilised as part of a wider structural system. In many standard domestic framing projects, they are used alongside timber with a C16 strength rating for wall studs where spans are less demanding. For more intensive engineering requirements, such as high-load floor planes or wider roof spans, these lengths are often specified in conjunction with premium C24 structural wood to ensure the assembly maintains its stiffness and integrity under stress.
To preserve the lifespan of the structure, it is essential to use appropriate fixings and to apply end-grain preservative to any areas cut during installation. This material also integrates seamlessly with other carcassing components such as wall plates and structural timber joist solutions to form a complete, code-compliant skeleton for the building.
Frequently Asked 5x2 Questions
What Is Regularised 5x2 Timber?
Here at Materials Market, all our timber (including our 5x2 wood) is treated with preservatives, kiln dried, and then planed all round to give it eased edges that make for easy handling (regularised).
Planing is a process in which the timber is sanded down to achieve a smooth finish, banishing imperfections and making it suitable for aesthetic use within a building or furniture building.
What Is 5x2 C24 Timber?
The term "C24 grade" is used to describe a higher timber quality than that of C16.
C24 timber is a premium choice that can support higher loads and wider spans.
Only timber imported from areas where the weather conditions demand a slower growth rate (and hence a tighter grain) achieves a C24 grade.
Thanks to the protective treatment and C24 grading of 5x2 treated timber, it is suitable for use in a variety of indoor and outdoor applications.
Is It Possible To Paint 5x2 Treated Timber?
Yes, you can absolutely paint treated timber. However, it is a good idea to allow the wood to dry completely before adding any paint or primer to it.
This can take up to a few weeks depending on the environmental conditions of the storage area.
Heat and direct sunlight can cause the treated timber to warp instead of dry out and damper conditions can prolong the drying out period.
What Are The Benefits of Using 5x2 Treated Timber?
There is an abundance of timber types available on the market from sawn treated timber, untreated timber and sawn carcassing timber.
No matter your project, it is essential to always use good quality treated timber as timber is usually located in places that are not easy to get to. This means we usually have no way of knowing if parts of the structure are under attack from insects or dampness.
With C24 graded timber, you won't need to pay mind to 'checking in' on the timber, as its pressure treatment renders it unaffected by both fungal and insect attack. Essentially meaning, it can fend for itself without you maintaining it.
Here are just a handful of the benefits on offer with treated timber:
- It is treated to resist rot, decay and insect attacks
- The most durable timber option, making it ideal for outdoor use
- Thanks to its treated nature, treated timber is also low-maintenance
- You won't have to spend time and money regularly maintaining it
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