Lumber and Plywood
Wood is among the world’s most sustainable building materials. In fact, trees’ ability to absorb carbon dioxide and emit oxygen make wood the only building material that is renewable and has a positive impact on the environment. Treating lumber and plywood used for homes and other structures with borates provides protection from termites – including the voracious Formosan termite – decay fungi, carpenter ants, and wood boring beetles. Lumber and plywood can be treated through a vacuum pressure process, or by dip-diffusion. Pressure-treatment is used most often in North America while other parts of the world rely on dip-diffusion. While both methods are effective, treatment standards may differ according to location.
Flame retardant-treated lumber and plywood have often been successfully used in structures exposed to temperatures less than 100°F (38°C). The usual method of treatment of dimensional lumber and plywood is by vacuum/pressure impregnation with aqueous solutions of flame retardants. Flame retardant plywood can also be produced by impregnation of individual veneers, often just by soaking, prior to assembly and gluing into plywood. It is necessary to ensure compatibility between the flame retardant additives and the adhesive system to obtain strong bonding. Boron compounds by themselves are effective flame retardants in lumber or plywood. They can be used in conjunction with other flame retardant chemicals including ammonium sulfate, diammonium phosphate or zinc chloride.