Tanalised Treated Timber 75 x 100mm 4.8m – 4×3 Timber
Tanalised Treated Timber 75 x 100mm 4.8m is a versatile pressure-treated softwood section suitable for building, landscaping and outdoor construction projects. It is commonly referred to as 4×3 timber, based on its traditional approximate imperial dimensions of 4 inches by 3 inches.
Supplied in a long 4.8-metre length, this timber is useful for creating frameworks, supporting garden structures and completing general external carpentry. Its rectangular 75 x 100mm section provides a substantial piece of timber while remaining manageable to cut and install using suitable woodworking tools.
The timber has undergone a pressure-treatment process to help protect it against fungal decay and wood-destroying insects. This improved resistance makes it more suitable than untreated softwood for many outdoor and exposed applications.
Product dimensions
The nominal product dimensions are:
- Metric section: 75mm x 100mm
- Common imperial name: 4×3 timber
- Length: 4.8m
- Material: Treated softwood
- Treatment: Pressure treated or tanalised
- Finish: Sawn timber
- Suitable for: Building, landscaping and outdoor projects
The name 4×3 is a familiar trade description. It should not be treated as an exact finished measurement, and the stated metric dimensions should be used when planning a project.
What is tanalised treated timber?
Tanalised timber is timber that has been treated with wood preservative under controlled pressure. During manufacture, the timber is placed inside a treatment vessel so the preservative can penetrate further into the wood than a simple surface coating.
This treatment helps protect the timber against fungal decay and wood-destroying insects. It can extend the timber’s service life when the material is correctly specified, installed and maintained.
Pressure treatment does not make timber completely waterproof or immune to weathering. Exposure to rain, sunlight, moisture and changing temperatures may still result in movement, small surface splits and gradual colour changes.
Any cut ends, drilled holes or notches created during installation should be coated with a suitable end-grain wood preservative. This helps restore protection to the areas where the factory-treated surface has been broken.
Common uses for 4×3 treated timber
The 75 x 100mm section offers a useful balance between size, strength and versatility. Depending on the project design and specification, it may be used for:
- Outdoor timber frameworks
- Garden structures and features
- Landscaping projects
- Pergolas and sheltered structures
- Agricultural and equestrian projects
- Timber supports and bearers
- Raised garden features
- External carpentry and joinery
- General construction work
- Bespoke timber projects
- Heavy-duty garden edging
- Repairing existing outdoor structures
Where the timber will carry structural loads, confirm that its strength class is appropriate for the proposed use. Treated timber should not automatically be assumed to be structurally graded unless it is specifically marked and sold with a recognised grade such as C16 or C24.
Natural characteristics of timber
Timber is a natural product, so each length will have its own grain pattern, knots and colour variations. Features such as resin pockets, surface checking and small splits may occur and are not necessarily defects.
The pressure-treatment process introduces moisture into the timber. As it dries, the wood may experience some shrinkage, twisting, cupping or bowing. These are natural characteristics that can vary depending on storage, exposure and moisture conditions.
Treated timber may initially have a green or brown appearance depending on the preservative system used. This colour will generally fade and weather over time when the timber is installed outdoors.
Treatment marks and shade variations may also be visible between individual lengths or manufacturing batches.
Important sizing information
Please note: Timber dimensions are nominal and may vary slightly due to the manufacturing process, pressure treatment, moisture content and natural movement of the wood.
The common name 4×3 is an approximate imperial description of the timber section. Customers requiring precise dimensions should measure the timber before installation or contact us to confirm the specification of the available stock.
Allowing the timber to acclimatise before installation can be helpful where accurate joints or close fitting tolerances are required.
Cutting and installation
Use suitable, sharp woodworking tools when cutting or drilling the timber. Appropriate gloves, eye protection and respiratory protection should be worn when handling, sawing or sanding treated wood.
Avoid breathing in timber dust and work in a well-ventilated area. Collect sawdust and offcuts for responsible disposal. Pressure-treated timber should never be burned on a domestic fire, garden bonfire or in a wood-burning appliance.
Apply a suitable end-grain preservative to all freshly cut ends, drilled holes and notches. Use corrosion-resistant fixings that are compatible with treated timber, particularly for external installations or areas exposed to regular moisture.
Supports and fixings should be appropriate for the intended application. Where the timber performs a structural function, installation should follow the approved drawings and specifications.
Storage and maintenance
Before installation, store the timber flat, raised off the ground and supported at suitable intervals. Protect it from prolonged saturation while allowing air to circulate around the lengths.
For visible external projects, a compatible wood stain, oil or protective coating may be applied once the timber has dried sufficiently. Follow the coating manufacturer’s instructions regarding surface preparation and moisture content.
Periodic maintenance can help preserve the timber’s appearance and service life. Pay particular attention to cut ends, joints and horizontal surfaces where water could collect.
Key benefits
- Substantial 75 x 100mm timber section
- Commonly known as 4×3 timber
- Supplied in a versatile 4.8m length
- Pressure treated against fungal decay and insects
- Suitable for many outdoor and landscaping projects
- Useful for frameworks, supports and garden structures
- Can be cut and worked with suitable timber tools
- Suitable for professional and DIY projects
- More durable than untreated softwood in suitable conditions
- Versatile rectangular timber section
Tanalised Treated Timber 75 x 100mm 4.8m – 4×3 Timber is a practical choice for outdoor frameworks, landscaping and general building applications. Always confirm the dimensions, strength grade and treatment suitability against the requirements of your project before installation.
