What is Treated Timber?

It’s quite a wide term, with consideration to both commercial and domestic applications. What we aim to clearly define is commercially treated timber that would be purchased in timber merchants or used in all manner of construction/contract based work.

A natural product

Whilst timber is a sustainable and beautiful material to use, both out and inside, it is a natural product and without any treatment, it will, however, deteriorate over time. For internal timbers such as trusses, joists and framework, that might be deterioration from insects and fungi, whilst for timber that is used externally, damage can come from environmental factors such as the weather.

In all of the above situations, the service life of the wood can be maximised by choosing treated timber.

So what is the treatment process?

The principle of creating treated timber is generally the same, whatever the spec of treatment. The packs of timber are manoeuvred into very large tanks which are then sealed and filled with the appropriate preservative chemicals and water.

The treatment process is either described as high or low pressure and which to use is determined by many factors. High-pressure timber treatment can also be called vacuum pressure timber treatment. The chemical mixture penetrates deep into the wood to provide long-lasting protection.

Commercially treated timber offers a thorough and professional result every time and delivers excellent durability.

When to use low pressure treated timber

Internal timbers tend to be treated with a low-pressure process. In terms of Use Class, this is 1 and 2. Typical applications include joinery, CLS framing, trusses and flooring. The treatment protects against inserts and fungi for the lifetime of the building. If the timber is going to be exposed to moisture then the treated timber will need a coating to help protect it.

Low-pressure timber treatment uses less water and so the wood returns to its optimum moisture content and dimensions far more quickly. It also remains a more natural colour, compared to high pressure treated timber.

When to choose high pressure treated timber

If the wood is to be used outside, high-pressure timber treatment is essential. In Use Class terms, that’s 3 and 4. Typical end use includes cladding fence posts, garden furniture and decking. The chemicals need to penetrate deep into the wood in order to provide sufficient protection and so a high-pressure process is used. The further the chemical penetrates into the wood, the higher the Use Class. Timber to be used in the ground must be treated to Use Class 4. Service life varies from 5 to 30 years dependant on a number of factors such as wood species, level of treatment and end use.

Wood Lane Timber Merchants Ltd supply a large range of treated timber products. For additional product information please call 0115 964 0888 or email us at sales@woodlanetimber.co.uk.

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