Deals with requirements for penetration and for retention of a range of preservatives for timber, veneer and plywood intended for use in conditions where the material is exposed to certain decay and insect attack hazards. The compositions of acceptable preservatives are given, and recommended treatment and levels are listed according to the anticipated decay or insect attack hazard. Appendices give information on the sampling of preservatives and preservative-treated wood; on the determination of the penetration and retention of preservatives in wood; on the in-ground durability of various species of timber; and a method for detecting Lyctus-susceptible sapwood in timber.