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How Is Timber Pressure Treated?

Post on 9th December 2020

You’ll probably have heard of the phrase ‘You have a way with words’, well here at Slatted Screen Fencing, we have a way with woods. There are premium qualities we look for in the timber we select to ensure it keeps its stunning looks for years, and that doesn’t happen by accident. Our range of fencing includes Canadian Western Red Cedar and Siberian Larch which are both incredibly popular, but our Pressure Treated Timber fencing panels pack their own punch too. In order to appreciate the benefits of Pressure Treated Timber, it helps to understand the pressure-treating process and what actually happens to the wood before it gets to us.

What is Pressure Treated Timber?

In a nutshell, Pressure Treated Timber, also referred to as tanalised timber, is wood which has had protective chemical preservatives forced deep into it under extreme pressure. The very nature of fencing and the fact it is outdoors all year round means the timber it is made from is constantly exposed to the many conditions which deteriorate natural wood. It’s an organic product, so wind, rain, heat, ultraviolet light and continual temperature and humidity changes all shrink and expand the wood, which weakens it over time.

It is also susceptible to rot from the ground, and insects see it as a free meal too, so it actually has a fair bit to contend with. Many people paint their fencing with protective treatments to combat the deterioration of the wood, but this is a very temporary process as those elements wear the protective coatings away too. Instead of only being protected at surface level, the process of pressure treating the timber forces all of that protection right into the grain of the wood. This means you won’t have to spend hours each year, trying to protect it from the outside as it’s already protected from the inside no matter how much the exterior surface is damaged.

How does the Pressure Treated process work?

For us, the selection process starts way before the timber is pressure treated. There are criteria the wood must meet in order to make the cut, pardon the pun:

  • The wood type is selected from specific mills we’re happy to work with
  • The moisture content of the wood is checked to ensure it is low enough to accept the pressurised preservative treatment
  • All timber is tagged with information vouching for its type, source location, quality and any applicable trademark stamps as it will have been inspected thoroughly by this point

Add to this that we are an environmentally conscientious company too. Being eco friendly and only using sustainable resources are important aspects of our ethos so we rigorously check the suppliers we use, and the chemicals they apply to the products we select.

Let’s Apply Some Pressure…

Once the wood and suppliers have met our requirements, the timber being used is then ready for treatment. The wood is placed into a large steel vacuum pressure cylinder which is then sealed. After being completely sealed, a powerful industrial vacuum pumps all of the air out of the cylinder. This vacuum is so strong, it pulls the air and moisture out of the wood too. Imagine a sponge which has been completely wrung out – it is now extremely compacted ready to absorb anything around it as it expands again. The preservative solution is then flooded into the cylinder, and the voids in the wood which have been created by the vacuum, make it so sponge-like, it sucks up the solution and absorbs it. To force the preservatives even deeper into the wood cells, extreme pressure is applied too.

Various wood species and retention levels will affect the capacity of the wood and how long they need this treatment for, so these will dictate the pressure settings and length of cycle needed for this process. This step is crucial as done properly, this process can strengthen the wood too so it’s essential this step is conducted with precision. At the end of this cycle, the cylinder will be drained and a pump used to remove the surplus solution from the wood. A further vacuum cycle is then run to remove any excess preservative solution from the wood. When complete, the wood can be removed, and placed for 24-48 hours on a drip-pad where the freshly treated timber can drain and start to dry naturally. It is now ready to make its way to us!

The Benefits Of Pressure Treated Timber

The pressure-treating process gives the wood additional advantages over non treated timbers which we covered in the Know Your Wood: Pressure Treated article, including:

  • Pressure Treated Timber Is Stronger
  • Pressure Treated Timber Is Long Lasting
  • Pressure Treated Timber Is Low-Maintenance
  • Pressure Treated Timber Is More Economical

It is important that the pressure-treating process is conducted properly in order to give it those qualities. There are various factors which could affect the quality of the final product.

The timber needs to be of a specific type, age, moisture level and quality. The preservatives need to meet strict quality and safety standards. The cycle times need conducting properly in order to strengthen the wood as opposed to weakening it. The pressure needs to be correctly applied to ensure the wood is infused properly and thoroughly. Any gap in any one of these processes would result in an inferior product which is why we are meticulous with our selection process. The benefits of Western Red Cedar And Siberian Larch are significant, so we only ever use premium quality pressure treated timber to compliment our selection. A good quality pressure treated timber offers instant protection against the elements. It is strong and doesn’t soften so is less prone to damage and the bugs will hate it so they’ll dine and live elsewhere. All of this protection helps you fully enjoy having an attractive fence instead of needing to keep one eye on whether you need to get your paintbrush out. If you’d like to know more about our pressure treated range, get in touch and our team will happily talk you through the best options for your needs.