Compilation of reports. 1. Performance of treated lumber against termites after 11 years of test in Ontario. 2. Performance of borate-treated wood against subterranean termites under above-ground protected conditions in Canada
North American subterranean termites have become a major factor limiting the service life of wood products in southwestern Ontario. If preservative treatment can be demonstrated to prevent termite attack, the market for wood products could be maintained and expanded. With the assistance of the town of Kincardine, Ontario, Forintek set up a ground-contact termite test site in 1988. The material used included 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 inspected in the summer of 1999. Treated material was generally performing well, with some pieces starting to show signs of superficial surface feeding, or cosmetic damage. Some samples that had lower assay retentions and preservative penetrations showed more than just trace nibbles and termites appeared to have actually penetrated through the outer treated zone. It appeared that termite entry occurred in areas on the wood surface where defects may have facilitated such entry. Material that came close to meeting CSA O80 standards for ground contact generally suffered only minor damage.
Forintek expanded the test in 1996 to include borate-treated material above-ground, protected from rain. This method simulates the sillplate, or dodai, used in traditional Japanese housing construction. The material included hemlock and amabilis fir lumber treated with borate and chromated copper arsenate (CCA). When it was inspected in the autumn of 2000, the treated material was generally found to be performing well, with some pieces starting to show signs of superficial feeding or cosmetic damage. Attack was moderate on untreated controls.