In Finland, Impregnated timber is pine timber that has been impregnated with an impregnation agent containing copper compounds (C impregnation) into classes A and AB. In terms of colours, in addition to the traditional green there is also brown, which is made by adding a coloured pigment to the impregnation agent.
Classification of Impregnated timber:
- impregnation class A, thickness of sawn timber = > 48 mm: structures in contact with the ground and water
- impregnation class AB, thickness of sawn timber = < 48 mm: structures above the surface of the ground
The most common lengths of Impregnated timber vary between 2.7 m and 5.4 m in steps of 300 mm.
In terms of fasteners and mountings for impregnated wood, in all load-bearing structures and structures significant from a point of view of personal safety (e.g. steps and railings), only fastenings made of stainless steel should be used. The thickness of the layer of zinc in hot-galvanised products that may be used in other structures should be at least 90 micrometres.
Impregnated timber is classified as separately recyclable waste, so all such timber and possible machining waste that are being thrown away must be sent to special recycling points at waste disposal plants or timber retail outlets.