Tanalised Treated Timber 47 x 100mm 4.2m – 4×2 Timber
Tanalised Treated Timber 47 x 100mm 4.2m is a versatile pressure-treated softwood section suitable for outdoor construction, landscaping and general building projects. It is commonly referred to as 4×2 timber, based on its traditional approximate imperial dimensions of 4 inches by 2 inches.
The 47 x 100mm section is one of the most widely used timber sizes for general building, garden and DIY work. Its 4.2-metre length provides useful additional coverage for medium-to-large projects while remaining easier to handle than longer 4.8m or 6.0m lengths.
The timber has undergone a controlled pressure-treatment process to provide additional protection against fungal decay and wood-destroying insects. This treatment makes it more durable than untreated softwood when correctly specified, installed and maintained in a suitable environment.
Product dimensions
The nominal product dimensions are:
- Metric section: 47mm x 100mm
- Common imperial name: 4×2 timber
- Length: 4.2m
- Material: Treated softwood
- Treatment: Pressure treated or tanalised
- Suitable for: Building, landscaping and outdoor projects
The common name 4×2 is a traditional trade description rather than an exact conversion of the metric dimensions. Use the stated metric measurements when planning, cutting and installing the timber.
What is tanalised timber?
Tanalised timber is softwood that has been treated with wood preservative using a controlled vacuum and pressure process. This allows the treatment to penetrate deeper into the timber than a standard brush-applied surface coating.
The preservative helps protect the wood against fungal decay and attacks from wood-destroying insects. This makes treated timber suitable for many outdoor, exposed and moisture-prone construction projects.
Pressure treatment does not make the timber completely waterproof or maintenance-free. The wood can still absorb and release moisture, resulting in movement, shrinkage, surface checking and gradual colour changes.
When the timber is cut, drilled or notched, internal wood may be exposed. Apply a compatible end-grain preservative to all newly exposed areas to help maintain the protection provided by the original treatment.
Common uses for 4×2 treated timber
The 47 x 100mm section is highly adaptable and can be used for many construction, landscaping and garden projects.
Depending on its strength grade and the project specification, possible applications 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 repair and maintenance work
- Bespoke outdoor structures
- Load-bearing members where correctly graded
- Garden and DIY projects
Where the timber will carry structural loads, confirm that it 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.
The required span, loading, support spacing, connections and fixing arrangement should be confirmed by a suitably competent person for structural installations.
Benefits of the 4.2m length
The 4.2-metre length provides flexibility for projects that require greater coverage than a 3.0m or 3.6m length. Where appropriate for the design, it may help reduce the number of joints required within a framework.
It can also be divided into several smaller components. Preparing a cutting schedule before beginning work can help reduce waste and make efficient use of the timber.
Consider site access before ordering. Ensure there is enough room to unload, store and manoeuvre a 4.2m length safely.
The weight of the timber will vary according to its moisture content. Use suitable lifting assistance and safe handling procedures when moving multiple pieces.
Natural characteristics of treated timber
Timber is a natural material, so every length will vary in grain, colour, knots and surface texture. These differences are expected and contribute to the natural appearance of the wood.
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 relevant grading requirements.
Pressure treatment introduces moisture into the wood. As the timber dries, some natural shrinkage, twisting, bowing or cupping may occur. Correct storage and installation can help manage this movement.
Newly treated timber may initially have a green or brown appearance depending on the treatment system used. The colour will generally fade and weather gradually following outdoor installation.
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 4×2 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.
Allowing the timber to acclimatise appropriately can be beneficial where the project requires precise joints or close-fitting components.
Cutting and installation
Use suitable woodworking tools fitted with sharp blades when cutting or drilling this timber. Wear protective gloves, eye protection and appropriate respiratory protection while handling, sawing or sanding treated wood.
Carry out cutting in a well-ventilated location and avoid breathing timber dust. Sawdust and offcuts should be collected and disposed of responsibly. 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 every cut end, drilled hole and notch. Use corrosion-resistant fixings compatible with pressure-treated timber, particularly in external or moisture-prone environments.
For structural applications, supports, connections and fixings should follow the approved design and be suitable for the expected loads.
Storage and maintenance
Store the timber flat, raised above the ground and supported at appropriate intervals. Protect it from prolonged saturation while allowing sufficient airflow around the lengths.
A compatible wood stain, oil or protective coating may be applied to visible outdoor timber once it has dried sufficiently. Follow the coating manufacturer’s preparation and moisture-content instructions.
Inspect external timber periodically, paying close attention to joints, cut ends, fixing points and areas where water could collect.
Key benefits
- Versatile 47 x 100mm timber section
- Commonly known as 4×2 timber
- Useful 4.2m length
- Pressure treated against decay and insects
- Suitable for outdoor frameworks and landscaping
- Useful for garden and agricultural structures
- Can be cut for different project requirements
- More durable than untreated softwood
- Suitable for professional and DIY construction
- Versatile for general external building work
Tanalised Treated Timber 47 x 100mm 4.2m – 4×2 Timber provides a versatile section and practical length for outdoor construction, landscaping and general building projects. Always confirm its exact dimensions, treatment level and strength grade against the requirements of the intended application before installation.
