Tanalised Treated Timber 47 x 125mm 4.2m – 5×2 Timber
Tanalised Treated Timber 47 x 125mm 4.2m is a versatile pressure-treated softwood section suitable for building, landscaping and outdoor construction projects. It is commonly referred to as 5×2 timber, based on its traditional approximate imperial dimensions of 5 inches by 2 inches.
The 125mm depth provides a useful intermediate size between commonly used 4×2 and 6×2 timber. This makes it a practical option for projects requiring a more substantial section than 4×2 without the additional depth and weight of larger timber.
Its useful 4.2-metre length provides flexibility for medium-to-large projects and may reduce the number of joints required compared with shorter lengths. It can also be cut into multiple smaller components where required.
The timber has undergone a controlled pressure-treatment process to provide additional protection against fungal decay and wood-destroying insects. This improves its durability compared with untreated softwood when correctly specified, installed and maintained in suitable external conditions.
Product dimensions
The nominal product dimensions are:
- Metric section: 47mm x 125mm
- Common imperial name: 5×2 timber
- Length: 4.2m
- Material: Treated softwood
- Treatment: Pressure treated or tanalised
- Suitable for: Building, landscaping and outdoor projects
The name 5×2 is a familiar trade description rather than an exact imperial conversion. Use the stated metric dimensions when measuring and planning your project.
What is tanalised timber?
Tanalised timber is softwood treated with wood preservative through a controlled vacuum and pressure process. This encourages the treatment to penetrate deeper into the timber than a simple brush-applied surface coating.
The preservative helps protect the wood against fungal decay and attacks from wood-destroying insects. It can help extend the service life of the timber when the material is installed and maintained in a suitable environment.
Pressure treatment does not make timber completely waterproof or maintenance-free. Outdoor exposure may still cause movement, shrinkage, weathering, surface checking and gradual colour changes as the wood absorbs and releases moisture.
When the timber is cut, drilled or notched, internal areas may be exposed. Coat these freshly exposed surfaces with a compatible end-grain wood preservative to help maintain protection following installation.
Common uses for 5×2 treated timber
The 47 x 125mm section is suitable for a broad range of outdoor and general construction work. Its suitability for a particular application will depend on its strength grade, treatment level and the project design.
Possible uses include:
- Outdoor timber frameworks
- Garden sheds and buildings
- Landscaping projects
- Timber supports and bearers
- Garden screens and dividers
- Agricultural and equestrian structures
- Raised garden features
- External carpentry and joinery
- General building work
- Bespoke outdoor structures
- Repairs to existing timber frameworks
- Load-bearing members where correctly graded
Where structural performance is required, confirm that the timber has the appropriate strength classification. Tanalised timber should not automatically be assumed to be C16 or C24 unless it is specifically marked and sold with that grade.
A suitably competent person should determine the required spans, loading, support spacing, connections and fixing arrangements for structural installations.
Benefits of the 4.2m length
The 4.2-metre length offers greater reach than common 3.0m or 3.6m timber while remaining more manageable than 4.8m and 6.0m alternatives.
Where appropriate for the design, using a longer timber length can reduce joints and create a more continuous framework. It can also be divided into several shorter pieces for different parts of the project.
Preparing a cutting schedule before work begins can help minimise waste and ensure the full length is used efficiently.
Consider site access before ordering. There must be sufficient space to unload, store, turn and position a 4.2m length safely. Timber weight will vary depending on moisture content, so use suitable lifting and handling techniques.
Benefits of pressure-treated timber
Pressure-treated softwood offers several advantages for outdoor projects:
- Additional protection against fungal decay
- Protection against wood-destroying insects
- Greater durability than untreated softwood
- Suitable for many external applications
- Useful for garden and landscaping projects
- Can be cut and worked with suitable tools
- Suitable for trade and DIY construction
- Supplied ready for appropriate outdoor use
The correct treatment or use class must still be selected for the intended environment. Timber installed in direct ground contact or exposed to persistent moisture may require a particular treatment specification.
Natural timber characteristics
Timber is a natural material, so each length will vary in grain pattern, colour, knots and surface texture. These differences are normal and form part of the natural appearance of softwood.
Knots, resin pockets, minor splits and surface checking may be visible. These features do not automatically indicate a defect, although their suitability will depend on the intended application and any applicable grading requirements.
The pressure-treatment process introduces moisture into the timber. As it dries, some shrinkage, twisting, bowing or cupping may occur. Correct storage and installation can help manage this natural movement.
Newly treated timber may initially have a green or brown appearance depending on the preservative system used. Its colour will generally fade and weather gradually following outdoor exposure.
Important sizing information
Please note: Timber dimensions are nominal and may vary slightly due to machining, pressure treatment, moisture content and the natural movement of the wood.
The common name 5×2 is an approximate imperial description rather than a guarantee of exact finished dimensions. Customers requiring precise measurements should check the timber before installation or contact us to confirm the current stock specification.
Allow the timber to acclimatise where appropriate before completing work involving close-fitting joints or accurate measurements.
Cutting and installation
Use suitable woodworking equipment with sharp blades when cutting or drilling this timber. Wear protective gloves, eye protection and appropriate respiratory protection when handling, sawing or sanding treated wood.
Complete cutting work in a well-ventilated area and avoid breathing timber dust. Collect sawdust and offcuts for responsible disposal. Pressure-treated timber must not be burned on domestic fires, in wood-burning appliances or on garden bonfires.
Apply a suitable end-grain preservative to all cut ends, drilled holes and notches. Use corrosion-resistant fixings compatible with pressure-treated timber, particularly in external or regularly damp environments.
For structural applications, all supports, connections and fixings should follow the approved project design and be suitable for the anticipated loads.
Storage and maintenance
Store the timber flat, raised away from the ground and supported at suitable intervals. Protect it from prolonged saturation while allowing sufficient airflow around each length.
For visible outdoor installations, a compatible wood stain, oil or protective coating may be applied once the timber has dried sufficiently. Follow the coating manufacturer’s preparation and moisture-content instructions.
Inspect external timber periodically, paying particular attention to joints, cut ends, fixing points and areas where water could collect.
Key benefits
- Versatile 47 x 125mm timber section
- Commonly known as 5×2 timber
- Useful 4.2m length
- Pressure treated against decay and insects
- Suitable for outdoor frameworks and landscaping
- Useful for garden and agricultural structures
- Can reduce joints in suitable frameworks
- More durable than untreated softwood
- Suitable for professional and DIY construction
- Practical intermediate size between 4×2 and 6×2
Tanalised Treated Timber 47 x 125mm 4.2m – 5×2 Timber offers a practical combination of section size and length for outdoor frameworks, landscaping and general building projects. Always confirm its exact dimensions, treatment level and strength grade against the requirements of the intended application before installation.
