Do you want a sponge full of chemicals in your back garden?

Do you have timber or wish to have decking in your back garden?

If the answer is yes, then perhaps part of your reason for choosing timber over other materials such as concrete or plastic is that timber is a natural, beautiful material. Timber of course comes from trees, and so each piece of timber decking is as unique as the tree it came from. It has grown naturally in the forest and is a fantastic material to use if you care about the environment, as timber is renewable. You can replace trees by growing more trees – they are not finite in the way that other materials, such as plastic, are.

If you are the sort of person who has purchased timber decking for the above reasons then you are probably under the impression that what you own is a completely natural product. Unfortunately, you would be wrong to assume that the timber in your back garden is completely natural. The chances are that the timber decking in your back garden or yard, that you sit on and have barbecues on at the weekends, that your kids play on, that your pets lick food from, may well be a sponge full of chemicals.

We’ll just let you absorb that for a moment (sorry for the pun!) Once it has sunk in (apologies again!) you are probably wondering … why? Why does this beautiful, natural material have to be full of chemicals, and what alternative is there?

The difference between heartwood and sapwood
Sapwood is the outer part of a tree. As the living part of the tree, sapwood is also full of sugars that keep the tree alive. These sugars make the sapwood part non-durable, i.e. susceptible to fungal attack.

As most people know, having been introduced to the concept of finding out how old a tree is by counting its rings from a young age, trees grow outwards. They start the size of a little twig, and then as they grow they keep increasing both their height and their girth. So, the oldest part of the tree is the inside, the core of the tree, and the youngest part is the outside. As the tree grows, over time it makes no sense for it to keep its centre part, its original core, alive. Therefore, the cells stop irrigating it and it solidifies, getting harder and stronger, and helping to support the growth of the tree by acting as structural reinforcement for the part of the tree that continues to be alive, essentially acting as a central pillar, helping it to continue to build height and girth.

In really old trees, such as the Yew trees that you often find in churchyards in the UK, the centre of the tree is so old that is has rotted away and the tree has become hollow. The heartwood, although dead, is the solid strong part of the tree, whereas the living part of the tree, that allows nutrients to flow up and down the tree from roots to leaves and from leaves to roots, is the sapwood. The amount of heartwood and sapwood varies from tree to tree, and also according to the type of tree. For example, pine has a very small amount of heartwood and is in fact almost entirely sapwood. This makes it very light and easy to work with, but also means it will rot if not treated since sapwood is non-durable.

Heartwood will last a longer as it is already stripped of its original sugars. Sapwood, however, is living tissue that is soft and permeable, easy to attack, and not resistant to fungi. Therefore, if you are going to use timber outside that is made from sapwood, or includes sapwood, you need to treat it or do something to prevent it from rotting.

How to stop sapwood rotting
The most common way to prevent sapwood from rotting is to treat it with chemicals. If timber is made from or includes heartwood, it won’t need treatment and won’t take much treatment – any chemicals that it is soaked in will not penetrate very deep into the wood as it is no longer very porous. However, it is a different story with sapwood. Sapwood is still alive, and its role is to transport liquid up and down the tree, so is in effect ready to absorb protection treatments, usually harsh biocide chemicals which it soaks up like a sponge. The most common timber used for construction is pine, which as mentioned earlier is almost entirely sapwood. So if you are building with treated pine, then chances are it will be full of chemicals, as it absorbs them very easily.

Whilst chemical treatment is ideal for preserving timber, it is not a very green or environmentally friendly choice. The chemicals that are generally used are heavy metals used as biocides such as copper. This is an improvement on what was previously used, which was chromium, and before that arsenic, which of course is a poison that is used in the production of pesticides, herbicides and insecticides. However, it is still not the most natural choice out there

What is the alternative to chemicals?
Apart from choosing species that have low sapwood content such as FSC® hardwoods, if you want to avoid metals and other nasty chemicals then you will be pleased to know that there is a safe alternative available called OrganoWood. Instead of pumping abundant timber such as pine with chemicals, a benign mixture of water and silicon is used.

Silicon is commonly found as silicon dioxide or silicates in sand and soil. Over 90% of the Earth’s crust is made up of silicate materials, making silicon the second most abundant element in the Earth’s crust after oxygen.

The silicon forms a physical barrier around the wood, and unlike the heavy metals is perfectly safe. Whereas the chemicals kill the fungi, the silicon barrier simply prevents them from eating the wood.

There is also an extra benefit to using silicon, which is that it makes the wood flame retardant. The creators of OrganoWood weren’t aiming for this to be the outcome of it, but it certainly is a great added bonus to know that your timber is a safe option for your home.

We can supply OrganoWood to you, and you can find out more about it and its benefits here on our website at or by downloading our OrganoWood brochure:

Who are EcoChoice?
EcoChoice are specialist suppliers of certified timber products for exterior works, including OrganoWood. We were formed in 2005 with the aim of promoting FSC certified timbers to the UK construction industry, helping customers to engage in a sustainable way with tropical forests instead of turning away from the deforestation problem. We offer products from a wide range of different timber species, including Ekki, Ipe, Cumaru and Iroko. We are passionate about supplying our clients with independently certified timber products while encouraging responsible and sustainable practices at the source level. To find out how we can help you, please call us on 0345 638 1340, email us on or for more information about our sustainable timber products, please visit our website

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