4x2 Timber Treated
(13 Products)47mm x 100mm treated timber provides a structural solution for internal and external framing. Pressure-treated to enhance durability against biological decay, these versatile lengths are essential for load-bearing applications including floor joisting, roof rafters, and robust timber studwork across residential and commercial projects.
Understanding 4x2 Treated Timber
47mm x 100mm sawn treated timber, traditionally known by its nominal 4x2 inch measurement, is a foundational component in modern UK construction. These sections are kiln-dried and strength-graded to ensure they meet the rigorous demands of structural carcassing. While highly versatile for stud partitions, for projects requiring a higher load-bearing capacity or longer spans, many contractors opt for 5x2 treated timber to provide additional stiffness and structural integrity within floor joist or roof rafter assemblies. By undergoing a high-pressure preservative treatment process, the timber fibres are deeply impregnated with biocides, significantly extending the service life of the wood when exposed to moisture.
The physical dimensions of these products are finished to approximately 45mm x 95mm, providing a smooth, eased-edge profile that is safer and easier to handle on-site. This consistency in sizing is critical for ensuring level floor planes and plumb wall frames. Each length is selected for its structural integrity, providing the mechanical resistance necessary for supporting heavy dead and imposed loads.
Whether supplied as individual lengths for bespoke framing or in high-volume bulk packs for large-scale developments, this timber range offers the reliability required for permanent structures. The dual-grading potential ensures that users receive material capable of performing in demanding structural environments, bridging the gap between standard domestic framing and more intensive load-bearing requirements.
Material Range
- Individual 47mm x 100mm Lengths: Single units of pressure-treated carcassing available in a comprehensive span of sizes from 2.4m up to 6m to minimise on-site waste.
- Bulk Timber Packs: High-quantity 121-length packs designed for trade-scale applications, offering the same treated durability in a cost-effective format for major installations.
Performance Benefits
- Preservative Protection: Pressure-treated with advanced fungicides and insecticides to prevent rot, fungal decay, and wood-boring insect attacks.
- Structural Grading: Kiln-dried and graded to ensure the material meets specific strength requirements for safety-critical installations.
- Dimensional Stability: Kiln-drying reduces the moisture content of the timber, minimising the risk of warping, twisting, or shrinking after installation.
- Eased Edges: Finished with rounded corners to improve manual handling and provide a more precise fit within framed assemblies.
Typical Applications
- Floor Joisting: Creating the primary horizontal support structure for internal flooring systems.
- Roof Rafters: Forming the structural framework for pitched roof designs in domestic extensions and outbuildings.
- Timber Studwork: Constructing load-bearing internal partitions and external wall frames.
- Decking Subframes: Providing the essential treated base-structure for external timber decking areas.
- Garden Structures: Building heavy-duty pergolas, gazebos, and bespoke timber outbuildings.
Specification & Standards
- BS EN 14081-1: Timber structures - Strength graded structural timber with rectangular cross section.
- BS EN 335: Durability of wood and wood-based products - Use classes of biological attack.
- BS EN 350: Durability of wood and wood-based products - Testing and classification of the durability to biological agents.
Related Materials and Construction Uses
This treated timber range is frequently integrated with other structural components to create complete building envelopes. When used in floor or roof constructions, these lengths are often specified alongside specialised timber for structural joists to ensure the entire assembly meets the necessary span and load requirements. Depending on the specific engineering calculations for a project, these sections may be utilised alongside C16 strength-graded wood for standard walling or C24 premium structural timber for higher-specifications where superior knots and density are required.
To ensure long-term performance, these timber sections should be installed in conjunction with appropriate vapour control layers and breathable membranes. In external applications, all cut ends must be treated with a suitable end-grain preservative to maintain the integrity of the pressure-treatment envelope.
Frequently Asked 4x2 Questions
Can I Paint 4x2 Treated Timber?
Absolutely! Painting treated timber wood will not only help you achieve your ideal aesthetic but also gives the wood an additional layer of protection, which is something you want. When painting pressure-treated wood, however, you must be careful.
Most 100mmx50mm timber is still “wet” and needs time for the chemicals permeating the wood to settle and dry. At this point, the wood is noticeably heavy and will still feel damp to the touch.
If primer or paint is added to it at this point, there is every likelihood that it will be rejected by the water-based chemicals that are still working their way through the wood.
It is important to permit the timber to dry out fully before attempting to add paint or primer. This can be a lengthy process and may even take up to a few weeks depending on where the wood is stored.
If there is too much heat and direct sunlight, this can cause the treated timber to warp instead of dry out. Damp conditions can also prolong the drying-out period.
How Can I Tell if 4x2 Wood is Treated?
There are a few indicators that 4x2 timber has been pressure treated. The first is that it should be labelled as such with a stamp. However, when timber is cut to size, this occasionally gets removed.
Another tell is the colour of the timber; treated wood that is still relatively new should have a green tinge to it. This green hue fades over time and becomes honey gold before turning silver.
The smell can also be an indication, but this is only really effective when the wood is relatively fresh. New pressure-treated wood will carry a slight chemical smell, whereas non-treated wood won't. Again, this isn't a foolproof method and only works on freshly treated timber.
What's The Difference Between 4x2 Treated Timber & 4x2 Sawn Timber?
4x2 Sawn timber is wood that has been cut to the required dimensions but hasn't yet been pressure treated and kiln dried. 4x2 Pressure-treated timber, otherwise known as tanalised timber, provides many benefits, such as resistance to the elements.
The goal of pressure treating wood is to force preservative chemicals deep into the timber's cellular structure. This pressure treatment process will often include copper and organic co-biocides, which help to repel both insects and moisture.
Is 47x100 Treated Timber Environmentally Sustainable?
All of the timber lengths sold by Materials Market has been responsibly sourced.
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Complete Guide to 4×2 Timber: Sizes, Grades & Uses
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How To Build A Decking
How To Build A Stud Wall
How To Build A Pergola
How to Build a Timber Frame Extension
Timber Frame Construction
Timber Sizing
C16 vs C24 – What’s The Difference?
