Before it finds its way into a construction project, timber will need to have undergone several processes. The tree will have been cut down, split, left to dry in a controlled environment, and then sawn into lengths of the appropriate dimensions. In some cases, timber is put through an even lengthier process, designed to help it to withstand certain environmental challenges.
Introduction to Treated Timber in Construction
‘Treated’ timber comes in several different categories. Different sorts of treatments will yield improved performance in different sorts of settings.
Pressure-Treated Timber
Pressure treatment involves using pressure to force protective chemicals into the timber, rather than simply coating it. In this way, it provides protection against attack by the natural world. Wood that would ordinarily be chewed up by small insects and microbes can safely be used outdoors when it’s been treated. As such, pressure-treated timber is a popular choice in outbuildings and patios.
Fire-Retardant Treated Timber
One of the major disadvantages of timber is its flammability. Fire-retardant timber aims to combat this problem. It’s used in structures which require special protection against fire (like cinemas, theatres, hospitals, schools and libraries), and it can be essential in complying with building regulations.
Chemical Preservatives for Timber
Several different kinds of preservatives are used in the treatment of timber. Two stand out as worth knowing about:
Borate products use salt to do their job. The upside here is that the wood looks identical to timber that hasn’t been pressure-treated. The downside is that the salt can be washed out into the surrounding environment.
Alkaline copper quarternary is a more environmentally-friendly alternative. It’s slightly toxic, and so shouldn’t be used where animal (or human) food is being served. Provided that the chemicals stay inside the timber, it’s an ecologically-sound choice.
Benefits and Considerations of Treated Timber
Treating timber is an expensive process, and these costs are passed to the consumer. So what makes this process worthwhile?
Structures made using pressure-treated timber will tend to last much longer. If you’re building something outdoors, you’ll save money in the long run by using pressure-treated materials. This, after all, will save you from having to build the structure again.
On the other hand, pressure-treated timber will need to be cared for if you’re going to get the most from it. Research what’s required before you make the investment.
It’s also worth considering the colour of the timber you’re buying. The pressure-treatment process can often give timber a slightly green tinge, depending on the chemical being used. Moreover, many manufacturers will deliberately colour their timber, to indicate the standard to which it conforms. For example, you might see blue timber used to demonstrate compliance with National House-Building Council standards.
