ABSTRACT
Before the most suitable preservation system can be selected the deterioration risk must be clearly defined. With normal structural wood it is possible to define situations where deterioration will certainly occur, and in these severe hazard conditions the use of naturally durable or adequately preserved wood is essential. Perhaps the most important severe hazard situation is ground contact and transmission poles, fence posts, railway sleepers (ties) and construction piles must be properly protected. In most marine situations protection is required against marine borers, and building structures require protection against the House Longhorn beetle and against Dry Wood termites in areas where there is a danger of attack by these insects. In all these situations the use of naturally durable wood is unrealistic as it is both scarce and expensive, and in practice preservative treatment is essential and often required under local regulations.
