Subterranean termites have become a major factor limiting the service life of wood products in southwestern Ontario. If preservative treatment can be demonstrated to deter termite attack, the market for treated wood products can be maintained and expanded. With the assistance of the town of Kincardine, Ontario, Forintek Canada Corp. set up a termite test in 1988. The material included commercially available red pine, lodgepole pine, jack pine, hemlock, white spruce, and mixed spruce-pine-fir. The preservatives were chromated copper arsenate (CCA-C), ammoniacal copper arsenate (ACA), and ammoniacal copper quat (ACQ). Both incised and unincised lumber was included in the tests where possible. Also used was CCA-treated hem-fir plywood.
The material was most recently inspected in the late summer of 2003. Treated material was found to be generally performing well, with some pieces showing signs of superficial surface feeding, or cosmetic damage. Some samples with low assay retentions and preservative penetrations showed more than just trace nibbles, and termites appeared to have actually penetrated through the outer treated zone. Termite entry occurred in areas on the wood surface where defects may have facilitated such entry. Material that came close to meeting Canadian Standards Association O80 standards for ground contact generally suffered only minor damage.
Material end-matched to that at Kincardine was installed at the same time at Forintek’s test site at Petawawa, Ontario, where termites are not present, with the aim of comparing rates of decay at the two sites. After 15 years of exposure, the wood samples at Kincardine show more pronounced decay than those at Petawawa, but the most significant damage is from termite attack. Termites are a much more serious threat than decay to treated wood with shallow preservative penetration.