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.
In the 3-year rotation of subject matter for the reports of the "Durability of Wood" project, attention has again turned to treated commodities. In these tests, we evaluate not only the efficacy of the wood preservative, but also the effect on performance of the quality of treatment that can be achieved with Canadian wood species. The collection of long-term performance data takes time and it is impossible to predict questions about standards for which answers will be needed in 10 or 20 years' time. Consequently, Forintek has maintained a comprehensive field-testing program covering a wide range of commodities, wood species, preservatives and treatment methods. The reports in this compilation cover decking, finger-jointed lumber above ground, shakes, millwork, fence posts, lumber in a termite area and needle-incised lumber in an accelerated ground contact test.
Softwoods - Preservatives
Glued joints - Finger - Preservation
Preservatives - Chromated copper arsenate (CCA)
Preservatives - Penetration
Preservation - Durability
Decking - Preservation
Shingles - Preservation
Thuja plicata - Shingles
Shingles - Durability
Preservatives - Ammoniacal copper arsenate (ACA)
Posts - Preservation
Preservation - Incising - Tests
Picea - Preservation
Pinus contorta Dougl. var. latifolia - Preservation
A field test of untreated and preservative-treated round fence posts has been ongoing at Petawawa, Ontario since 1937. Service life data on twenty eastern Canadian wood species was developed. In addition, treatments by a variety of pressure and non-pressure processes with waterborne and oilborne preservatives were tested. Thermal immersion in creosote was the most effective non-pressure method used. Brush treatments and cold soaking proved to be ineffective for long-term protection from decay. Pressure treatment utilizing standard waterborne (CCA and ACA) and oilborne (creosote, pentachlorophenol, and copper naphthenate) provided excellent protection from decay.
The fence delineating the FPInnovations – Forintek Division test site at Maple Ridge, BC was designed to be functional, but also to incorporate a study to determine whether a physical barrier between the soil and wood surface, in the form of a wrap, would affect the performance of ACQ-treated lodgepole pine roundwood in ground contact. After five years in the field test, the fence posts treated with two formulations of ACQ, both wrapped below ground up to the groundline and non-wrapped, remained sound.