Pressurised timber and Tanalised timber are in fact the same thing. This type of timber is carefully treated with a chemical mixture that makes the wood strong and durable. The treatment, often known as Tanalith E, is applied under pressure which ensures that the chemicals absorb deeply into the wood. Pressure treated/tanalised timber is much more resistant to rot, mould, fungus, insects and extreme weather conditions.

How Is the Tanalised Timber Made?

The pressure treating process is actually really simple. The wood is placed into a large tank that is vacuum sealed. The chemicals are pumped into the tank and due to the vacuum, the chemicals are forced several millimetres deep into the wood. After this process, the timber will be left to dry.

A mixture of chemicals is used to treat the timber, the dominant one being copper which offers excellent protection against decay and insect attacks. The chemical mixture often contains a biocide as well which helps to kill naturally occurring rot and moulds that the copper cannot prevent. The chemicals used in tanalised wood are generally safe and this means that the treated timber can be used around children and pets without any problems.

How Long Will Pressure Treated Wood Last?

This may vary depending on the location of your timber structure and its exposure to the elements. A shed placed in a sheltered corner of the garden will generally last longer than one placed on top of a hill in a cold and windy climate. Generally, tanalised timber will last for several years rot free. 30 years is usually a good estimate for it to last without any additional treatment, stains or paint. Obviously, if you choose to treat it, this will prolong its life.

How Do I Tell If The Timber Has Been Treated?

Pressure treated timber will be stamped to state that it has been treated, however, this may be cut off if the timber is cut to size. Freshly treated timber is easily recognisable due to its green tinge. The green colour will fade to become a golden colour then eventually a silvery-grey over time.

Do I Need To Treat Tanalised Timber?

The short answer is no. It is already treated and will last a long time however, treating it helps to prolong the life of the wood and because this type of timber changes colour over time, treating it will help to maintain its original colour.

What Can I Use Pressure Treated Timber For?

Tanalised timber is fantastic for a wide range of applications, especially where the timber will be exposed to changing weathers. It’s great for internal and external structure joists and can be used in contact with the ground and fresh water. It is ideal for building decking, garden furniture, fencing and landscaping.

Can I Paint or Stain The Timber?

Whilst the timber will not need staining or painting, it will last perfectly well outside without any additional treatment, should you wish to paint or stain it then it will certainly help the longevity and maintain a uniform colour, preventing fading.  

If you choose to stain your timber it is recommended to wait until it has been out in at least three dry days so that the tanalith oxidises and the wood dries. If you intend to paint your timber then it is best to wait approximately six months.  Use an exterior primer first, preferably one that states it is fine to use on pressure treated timber.  Once your primer is dry, you can use an exterior paint to paint it the colour of your choice.  We find that latex-based paints give the best overall finish.

We hope after reading this article that you have a better understanding of what Tanalised Timber is.  It’s long lasting, strong and durable and suitable for a variety of home, commercial and industrial uses.  You can shop our range of Treated Timber here at KPT Timber.