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.
The first paper, Understanding Biodeterioration of Wood in Structures, provides an overview of the subject matter and refers to a selection of textbooks for more detail. It provides some essential background on wood structure and composition, the range of wood-inhabiting organisms and their effects on wood. The colonisation sequence, the conditions required for decay, and the rates of growth and strength loss are covered in some detail. The second paper, Moisture Problems in Vancouver Condominiums reviews the background to the recent epidemic of decay problems in southwestern B.C. and Forintek's short-, medium- and long-term response. In the short term, Forintek has been assisting in the work of the Building Envelope Research Consortium (BERC) designed to understand and deal with these problems. In the medium term, we have developed a combination of safe low-level chemical treatments which will provide OSB with the same fungal resistance as Douglas-fir faced plywood. This paper also describes the long-term project Decision Aids for Durable Wood Construction.
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
MPB-affected pine sapwood features increased permeability to preservative treatment. Selection of post-MPB lumber heavy to sapwood for preservative treatment may add value and allow access to new markets. A new process, developed in New Zealand has shown promise to deeply penetrate dry lumber with termiticides without using a pressure treating plant. Borates are one of the components used as a buffer and carrier but the levels are not necessarily sufficient to protect against Formosan termites without the carbon-based termitides in the formulation. Performance data are required to assure customers of product durability. Short lengths of heavily blue-stained post-MPB lodgepole pine lumber were pressure-treated with ACQ-D and borates targeting levels recommended for protection against attack by the Formosan subterranean termites. Additional samples were treated by the new dip-plus-kiln-conditioning process to borate levels less than recommended retentions, with and without the addition of organic termiticides. The boards were installed in field tests in Hawaii and Japan at sites with confirmed populations of Formosan subterranean termites, and will be monitored annually for termite attack to determine if the lower borate retentions with and without carbon-based termiticides are effective.
In order to develop long term performance data on the ability of pressure treated wood currently being produced in Canada to resist termite attack, a test plot has been established at Kincardine, Ontario in an area of known termite activity. This particular location, where termites were first reported in 1954, was selected after an extensive evaluation of potential test sites in southwestern Ontario. Material for evaluation in the test plot was either supplied directly by the wood treating industry or purchased at local lumber retailers. This material consisted of incised and non-incised commodities, ie: 2x4 (50x150mm), 2x6 (50x150mm), 4x4 (100x100mm) and 6x6(150x150mm), of four species (red pine, jack pine, lodgepole pine, eastern spruce) treated with either copper chrome arsenate (CCA-C) or ammoniacal copper arsenate (ACA) preservatives to the requirements of the CSA 080 Wood Presevation standard. Some additional PWF grade pressure treated plywood and a number of untreated controls were also installed. Treatment penetration and assay retention determinations were carried out on all test material prior to installation in the test plot. After one year in service, almost half of the untreated controls showed signs of attack, indicating extensive termite foraging activity in the test plot area. While most of the pressure treated material was rated as sound, there were several individual pieces that showed superficial signs of termite attack. However, all of this particular material was known to be very poorly treated. In a separate test at the site, commercial copper naphthenate field cut preservative was found to be very effective in protecting untreated wood surfaces from termite attack.
As part of the eastern field testing program, Forintek Canada Corp. established the first Canadian termite test plot at Kincardine, Ontario in 1988 to address an industry need for performance data on treated wood commodities exposed to attack by the eastern subterranean termite. CCA-C and ACA treated red pine, jack pine, lodgepole pine, eastern spruce and SPF lumber of various dimensions was obtained directly from the wood treating industries or purchased from retail outlets for installation in the test plot. The material represents a wide range of treatment penetrations and assay retentions. After four years in service, the performance of untreated controls shows a continuing high level of termite activity in the main plot area, but a lower level in an annex area. A fairly high incidence of surface grazing was observed on much of the CCA-C treated lumber in the main plot. Although this superficial attack resulted in only cosmetic damage in most cases, there were a number of test pieces in which termites had clearly broken through the treated zone and were attacking untreated wood within the treated shell. Since most of this attack was found on non-incised CCA-C treated lumber with very shallow preservative penetration, this material was considered to be vulnerable to termite attack. Incised CCA-C treated and non-incised ACA treated lumber which came closer to meeting the CSA080 standard for ground contact applications continue to perform well and was considered to be resistant to termite attack. Copper naphthenate field cut preservative was also found to provide good protection againds termite attack.
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.