Termite resistant wood products

Use of either naturally-resistant woods, preservative treatments, or engineered wood products with enhanced insect/decay resistance represents a final line of defense in structural protection. Ideally, proper construction techniques, physical or chemical barriers, and baiting systems can be used to prevent termites from ever entering the structure. However, very few things in life work perfectly all of the time, so redundancy is valuable in termite prevention. If termites penetrate the outer defenses of the building, use of insect-resistant building materials ensures against structural collapse and allows sufficient time for the problem to be discovered and corrected. Laboratory and field tests against Coptotermes formosanus have demonstrated the preservative concentrations necessary for protection, and illustrate the different modes of action of different preservatives (toxicity vs. repellence). For example, borate and CCA (chromated copper arsenate) wood treatments are not repellent to termites, but a four-year field test in Hawaii indicates that only superficial cosmetic damage will occur even with long-term termite exposure and that the timbers remain structurally sound. In contrast, untreated timbers in this test were destroyed within a single year. Research on naturally-resistant woods indicates that these, too, are not immune to termite attack, but can be equivalent in resistance to preservative-treated wood. Steps must also be taken to protect engineered wood products, and viable approaches are incorporation of preservatives during manufacture or incorporation of wood or bark containing naturally-resistant extractives.