Vacuum Pressure Impregnation

Whether palisades, pergolas, carports or playground apparatus – wood needs protection.

Particularly when used outdoors in constant contact with earth, our indigenous, relatively low durability wood types are at risk from fungi, insects and the elements. Vacuum pressure impregnation can provide lasting protection for these types of timbers.

You can find extensive information on wood destroying fungi and insects on page About wood pests.


The structure of wood is similar to that of a sponge, with cell cavities and cell walls, which represent the actual wood. The aim of wood preservation is to coat these walls with preservative to protect them from decay caused by wood-destroying fungi and insects. The preservative penetrates deep into the wood with the aid of pressure and a vacuum. First the vacuum removes the air from the cavities to create space for the preservative solution, which is then forced deep into the wood under high pressure.

Depending on the wood type, the intended application or the wood’s moisture level, different variations of the vacuum pressure process can be used.

Vacuum Pressure Process 

Oscillating pressure process 

Double vacuum process 

Lowry process 

Royal process