Vacuum pressure impregnation, often simply referred to as pressure treatment, should be considered as the preferred factory treatment process for the long-term protection of softwood-based garden products; such as garden buildings, fencing, arbours and furniture.
Once in use, the impregnated preservative will enable the timber to resist rot and insect attack, ensuring the product purchased will last longer and so enhance your enjoyment of it.
Commonly having a green-tinge finish when new, pressure treated products are aesthetically pleasing and blend easily into a typical garden environment. The surface ageing process sees the finish pass from green to a honey-brown appearance, culminating with a silvery grey finish; all without loss of protection.
Find out more about the different treatments for sheds by watching our video below:
Why pressure treat timbers?
Untreated timber will rapidly degrade, whether it’s set into the ground or above exposed to the weather. Through the seasonal moisture stresses caused by Spring and Summer shrinkage, then Autumn and Winter expansion, exposed untreated timbers face a losing battle to resist decay.
Short-term treatment processes like immersion (dipped) or brush application (staining) of preservative will always offer only minimal surface protection, which can quickly thin and fade. These low-cost treatments are a false economy as they require annual replenishment, leaving you to spend further resources on both time and preservative.
Pressure treatment is the answer. Preservative is forced deep into the grain and pores of the timber, so that its anti-rot benefits are not lost through the effect of surface weathering. You get to simply enjoy the product year-after-year, no further treatment required.
How is my shed pressure treated?
Machined timber is allowed to dry naturally by air flow or with the assistance of a kiln, to reduce its moisture content to a level ready to draw in the preservative. It is then tightly bundled and placed upon a trolley system and fed into the pressure treatment tank. Sawmills commonly operate these tanks as they require skilled handling.
Once closed, air is removed from the tank by vacuum. The tank is then flooded with the preservative liquid, which with the help of hydraulic pressure is forced deep into the timber. After the allotted cycle the excess fluid is extracted under pressure and stored for re-use.
Once completely vented, the tank is opened and the timber is removed.