Tanalised Treated Timber 75 x 225mm 4.8m – 9×3 timber
Tanalised Treated Timber 75 x 225mm 4.8m is a large and substantial timber section suitable for demanding building, landscaping and outdoor construction projects. Commonly referred to by builders and tradespeople as 9×3 timber, it combines a generous 75mm nominal thickness with a deep 225mm nominal width and an extended 4.8-metre length.
The substantial dimensions make this timber suitable for projects requiring a heavier section than standard 2-inch-thick treated timber. It may be used for outdoor structures, substantial frameworks, landscaping features, agricultural projects and various general construction applications.
The timber has been pressure treated, often called tanalised, to improve its durability. This treatment helps protect the wood against fungal decay and attacks from wood-destroying insects, making it suitable for many projects where untreated timber could deteriorate more quickly.
Product Dimensions
The nominal dimensions of this timber are:
- Thickness: 75mm
- Width: 225mm
- Length: 4.8m
- Common imperial name: 9×3
- Finish: Tanalised or pressure treated
The term 9×3 timber is the commonly used imperial trade name for this section. Its supplied metric size is described as 75 x 225mm, although these measurements should be regarded as nominal rather than guaranteed finished dimensions.
The exact size can vary slightly because of machining, pressure treatment, moisture content and natural timber movement. Check each piece before beginning work where precise finished measurements are essential.
What Is Tanalised Timber?
Tanalised timber has undergone a controlled pressure-treatment process. During treatment, the wood is placed inside a specialist vessel, where preservative is forced into the timber under pressure.
This provides more effective protection than a simple surface coating. The treatment helps the timber resist fungal decay and attacks from wood-destroying insects, potentially extending its service life when it is installed correctly and used in an appropriate environment.
Pressure-treated timber is not completely waterproof and should still be installed using good construction practices. Provide suitable drainage and ventilation, avoid areas where water can become trapped and protect newly exposed surfaces after cutting, drilling or notching.
Common Uses for 9×3 Treated Timber
The large 75 x 225mm section makes this timber suitable for numerous heavy-duty projects. Potential applications include:
- Substantial outdoor timber frameworks
- Large garden structures and pergolas
- Heavy-duty landscaping features
- Agricultural and workshop projects
- Raised beds and large planters
- Timber edging and garden borders
- Repair and replacement projects
- General building and construction work
- Outdoor furniture frameworks
- Projects requiring a traditional 9×3 section
The 4.8m length provides excellent coverage for larger installations and can help reduce the number of joints required across extended runs. It may also be cut into several shorter components when a project requires multiple matching sections.
Due to its dimensions and length, this timber can be heavy and difficult to manoeuvre. Suitable lifting assistance may be required during unloading, storage and installation. Always support the timber correctly and use safe manual-handling practices.
The product’s suitability will depend on its intended purpose, treatment classification, expected loads and the overall project design. If it will be used for structural or load-bearing work, confirm that it carries an appropriate strength grade.
Pressure-treated timber is not automatically classified as C16, C24 or another structural grade unless it is specifically marked and sold as such. Structural spans, loads, fixings and supports should be determined by a suitably competent person.
Benefits of Pressure-Treated Timber
Timber used outdoors can be exposed to moisture, rain, temperature changes and insects. Pressure treatment improves the wood’s resistance to biological deterioration and makes it a practical choice for many exterior projects.
The principal benefits include:
- Improved resistance to fungal decay
- Protection against wood-destroying insects
- Suitable for numerous outdoor applications
- Longer potential service life than untreated timber
- Substantial 75 x 225mm nominal section
- Extended 4.8-metre length
- Suitable for professional and DIY projects
- Can be cut to suit individual requirements
Treatment requirements differ depending on how and where the timber will be installed. Timber used above ground may have a different treatment classification from timber designed for direct ground contact.
Confirm that the treatment or use class is appropriate if the timber will be placed directly against soil, subjected to continuously wet conditions or installed in a particularly demanding environment.
Natural Appearance and Variations
Timber is a natural product, so every length will have an individual appearance. Variations in grain, colour and surface texture are normal. Individual pieces may contain knots, resin pockets, minor splits, wane, treatment marks and other naturally occurring characteristics.
Freshly treated timber may have a green or light brown tint, depending on the treatment process and timber species. This appearance normally softens and changes as the wood is exposed to daylight and weather.
Changes in moisture content may cause timber to expand, contract, twist or develop small surface checks. These are common characteristics of natural wood and do not necessarily prevent the timber from being used for its intended purpose.
Please note that colours, sizes and finishes can vary slightly due to manufacturing and pressure-treatment processes. Product photographs should be considered representative, as individual pieces and different batches may vary in appearance.
Cutting and Installation
The timber can be cut using suitable woodworking tools. Because it is a substantial 4.8m length, ensure it is evenly supported before measuring or cutting. This will help improve accuracy and reduce uncontrolled movement.
Cutting, drilling or notching can expose internal areas that may not contain the same level of preservative as the original treated surfaces. Apply a compatible cut-end or end-grain timber preservative to all newly exposed areas, following the product manufacturer’s instructions.
Use fixings suitable for pressure-treated timber and the intended installation environment. Galvanised or stainless-steel screws, nails and bolts are commonly selected for outdoor projects because unsuitable fixings may corrode or cause staining.
Wear suitable gloves, eye protection and a dust mask while cutting or drilling. Work in a well-ventilated location, wash your hands after handling the timber and dispose of offcuts responsibly. Tanalised timber should never be burned.
Storage and Maintenance
Store the timber flat, raised clear of the ground and evenly supported along its full length. Protect it from prolonged heavy rain while allowing air to circulate. Uneven storage can encourage bowing, twisting and unwanted movement, especially with longer and heavier sections.
Once installed, the timber may be allowed to weather naturally or finished with a compatible exterior wood paint, stain or oil. Freshly treated or damp timber should be allowed to dry sufficiently before applying a decorative finish.
Inspect completed structures periodically for trapped moisture, loose fixings, damaged coatings or newly exposed timber. Carrying out maintenance promptly can help protect the wood and prolong the life of the completed project.
Tanalised Treated Timber 75 x 225mm 4.8m provides a robust 9×3 section for substantial outdoor building and landscaping work. Its pressure-treated finish offers improved durability compared with untreated wood, while the extended 4.8m length provides useful coverage for larger projects.
Always inspect the actual dimensions, condition, treatment specification and strength grade before installation. Seek professional advice for structural, retaining or load-bearing applications to ensure the timber and proposed design are appropriate.
