Categories in wood preservation hazard, risk, and use
In various countries hazard-, risk-, or use-categories have been established. The different terms seem to be only a sophisticated language problem, but they are rather a basic principle of the philosophy of wood preservation which is going to obtain importance with respect to the low reputation of chemical wood preservatives in an increasing number of countries. Whilst hazard signifies the fact that an attack may occur, the term risk implies the probability how often and how important attack may be. It further includes the consequences of a failure. Both are orientated towards the organisms, which may involve problems when using wood or wood-based products. Use-categories are directed towards the utilization of the material possibly or not exposed to an attack. The author is convinced that for the future of wood preservation it is essential to combine the hazard of possible attack with a risk assessment for the probability and the consequences of an attack. In addition, also a time assessment is needed to consider the intended service life of a timber component. Only a combination of these influences will lead to the most suitable way of wood protection under environmental impact conditions.