Thermally modified woods have many of the same attributes as western redcedar – dark colour, dimensional stability, decay resistance, and relatively low strength – and are poised to compete for many of the same markets. Although thermal modification generally increases durability, both species and modification process can affect the degree of decay resistance. There are currently insufficient data on the durability of thermally modified white spruce. The present work evaluates the durability of white spruce modified at two temperatures using the decay fungi Postia placenta and Gloeophyllum trabeum. Western redcedar was included in the study as a reference species of naturally durable wood. A laboratory decay test classified the wood modified at 190°C as moderately resistant to both fungi, while the wood modified at 212°C was resistant to both fungi. In comparison, western redcedar heartwood was classified as resistant/highly resistant to P. placenta, and highly resistant to G. trabeum.
In addition, three medium- or long-term decay tests were initiated. The Accelerated Field Simulator (AFS) test will generate decay resistance data from an accelerated above-ground exposure. The L-joint test will generate decay resistance data specific to the window industry. The field stake test will generate decay resistance data from exposure in ground contact. Together these tests aim to provide comprehensive information on the performance of thermally modified spruce in a range of environments that will help producers gain access to new markets.
Regulators and traders around the world need internationally accepted, economical, and environmentally friendly treatment options to sanitize wood and allow its safe trade. With methyl bromide being phased out by 2015 (Montreal protocol) and severely restricted in some countries, including Canada, new treatments are needed to support international trade. A promising alternative fumigant, phosphine, is more environmentally friendly, easier and safer to use, and cheaper than methyl bromide. It is registered by the Pest Management Regulatory Agency for use on wood in Canada. However, specific efficacy data against pests associated with wood products are needed if phosphine is to be accepted through IPPC as a treatment recognized under ISPM-15 or ISPM-28. Over the last three years, FPInnovations has developed small-scale methods for evaluating fumigant efficacy using 10L glass jars that allow accurate control of temperature, fumigant concentration, and exposure time. These tests have shown that commercially suggested dosages for phosphine (200-500 ppm for 3-5 days at temperatures above 16°C) were not effective in killing pine wood nematodes, two species of bluestain fungi and one decay fungus. Nematodes and fungi also survived exposure to phosphine for 5 days at 800ppm, at 15 and 20°C. With additional funds received by CFS in 2011, we conducted additional tests where pine wood nematodes, two bluestain fungi and one decay fungus were exposed to the following concentrations of phosphine: 300, 600, 1000, 1500, 2000, 2500 and 3000 ppm over 5 days at 20°C and 25°C. The fungi were not killed with any of the combinations, while the number of nematodes was drastically reduced, but they were not fully eradicated.
Further work is needed to evaluate additional concentrations and times, and determine field feasibility in collaboration with international partners before we could advise the Canadian government whether a submission of efficacy data on phosphine to IPPC would be likely to succeed.
As methyl bromide is being phased out or severely restricted by 2015, and kiln-heating (56/30) is not ideal for some products, there is a need to find alternative treatments for phytosanitary purposes. Specific efficacy data against pests associated with wood products are needed if alternative treatments are to be recognized under ISPM-15 or ISPM-28. This study evaluates the efficacy of radio frequency (RF) energy heating for the treatment of pinewood nematode (PWN) infected wood. Following the most current guidelines on efficacy testing, in stage 1 of the study, 13 temperatures were tested on small wood samples to determine the minimum lethal temperature that produced 100% mortality of nematodes. The results showed 100% mortality at a minimum temperature of 56°C (based on Infra-red thermal images data 55.5-57.4). Additional samples were tested at 54°C, 56°C and 58°C to show 100% mortality at a sample size sufficient to satisfy the Probit 9 requirement where at least 93,613 individuals must be tested without survivors. In stage 2 of the experiment, RF heating was tested on industrial sized wood blocks. Due to observed variability in heating profile and the presence of cold spots in stage 1, in stage 2 two temperatures (58 and 60°C) were tested to ensure the samples reached the minimum lethal temperature. Survival was observed in only one sample, which, according to temperature probe data, did not maintain the minimum lethal temperature after a one minute hold time. Probit 9 was also satisfied in stage 2. The results of this study showed that to effectively treat PWN infected wood the entire sample must reach at least 56°C for a minimum of one minute using RF heating. Further work in the industry is needed to design schedules and technology able to deliver the target temperature thought the profile of treated wood in industrial scale operations.
Our work to address phytosanitary trade issues has focused on finding alternative methods of treating wood and wood products to eradicate pests of concern. Alternatives to methyl bromide require specific efficacy data against selection of pests associated with wood products, if these treatments are to be recognized under ISPM-15 or ISPM-28. In this study, dielectric heating with radio frequency (RF) energy was tested on lodgepole pine wood samples infected with various species of fungi, including bluestain, decay and mold species. We targeted the following temperatures: 40° 56°, 60°, 65° and 70°C with a hold time of one minute using the same test methodology as in our parallel study on RF efficacy against pine wood nematodes. Results for fungi were variable with no temperature resulting in 100% mortality of all fungal species. A Neurospora species, Fusarium solani, Oligoporus placenta and Antrodia carbonica showed some indication of heat tolerance as some replicates survived treatment at 60°C, 65°C and 70°C. Variable results among many of the isolates tested suggest that longer hold times or higher target temperatures should be tested in order to find effective temperature and time combinations for killing fungi in lodgepole pine using RF.
Wood preservation standards typically specify quality assurance procedures to determine whether wood is adequately treated. As a result there is a need to identify sapwood and heartwood, and measure preservative retention and penetration. For spruce and hem-fir there are no reliable methods to differentiate sapwood and heartwood. For carbon-based preservatives, preservative retention measurement typically requires GC or HPLC analyses; the only methods available to determine penetration involve detecting a surrogate in the formulation rather than the active ingredients. Multivariate models based on near infrared (NIR) spectra have been used to predict a wide range of wood properties over the past 20 years. The present research evaluates the potential use of NIR-based models as quality assurance tools for the wood preservation industry. Models were developed to differentiate hemlock and amabilis fir sapwood and heartwood. Attempts to differentiate spruce sapwood and heartwood were unsuccessful. NIR-based models were also able to differentiate untreated wood from wood treated with DDACarbonate and wood treated with tebuconazole. Models developed to predict DDACarbonate and tebuconazole retention were moderately accurate, but likely not precise enough to replace current quantitative assays. However, the sensitivity to the presence of the actives may be sufficient for estimating preservative penetration. Further work is needed using small probes suitable for scanning increment cores to adapt this technology for industrial use.
In addition to conventional NIR, hyperspectral images were obtained to differentiate untreated wood from DDACarbonate- and tebuconazole-treated wood, but accurate calibrations could not be developed.
Antisapstain formulations require field efficacy data for registration in some jurisdictions. Efficacy data are also needed to assist chemical suppliers in evaluating new formulations, and to help mills select appropriate products. A standardized approach would increase the comparability of data, increase data acceptance more widely, and improve the chances of executing a reproducible and repeatable test. The American Wood Protection Association (AWPA) recently published a provisional evaluation method (PEM) for evaluating the efficacy of antisapstain formulations in a field test. This method needs to be tested before it can be standardized. The present work evaluates three antisapstain formulations using this method. For comparison, one of the antisapstain formulations was also evaluated using a modified version of the AWPA PEM, and using FPInnovations’ internal antisapstain field test method (the Tony Byrne method). In general, a statistically significant dose response was observed for most of the treatments at one, two, and four months regardless of the evaluation method used. Results were similar for stickered and close-packed samples in the AWPA PEM, and modified AWPA PEM. All of the methods were effective in evaluating antisapstain efficacy. However, the AWPA PEM was the easiest to set up and run. The alternative methods did not offer any advantages in the present test. The most significant problem identified in the AWPA PEM was the restriction that logs be milled within 48 hours of felling. This does not represent typical industry practice. We recommend that the evaluation method specify that the time between felling and milling be consistent with the best practices of local industry, and that lumber cut from the test logs be spotless (rated 0).
Carbon-based preservatives are susceptible to biological degradation whereas metal-based preservatives can only be chelated by fungal metabolites. While biodegradation may prove a disadvantage in long-term preservation of wood, recycling treated wood through bioremediation will recover value from end-of-service- life wood, and enhance the perception of wood as a sustainable building material. An experiment was designed to determine whether bioremediation of treated wood could degrade the wood preservative, leaving no residual contamination. The proposed research included an accelerated exposure of treated wood to mimic end-of-service-life preservative concentrations, followed by inoculation of the weathered wood with fungi. However, after one year of accelerated exposure, preservative concentrations were not sufficiently low to proceed to the bioremediation phase.
The Canadian wood preservation industry is at a competitive disadvantage in both domestic and international markets because our major species (e.g. spruce and pine) are difficult to impregnate as they are characterized by a thin sapwood band and refractory heartwood which limits chemical penetration. Achieving adequate penetration may be even more challenging for the next generation of carbon-based and micronized preservatives. Biological incising with Dichomitus squalens, developed in Austria in the 1990s, increased permeability in European spruce. More recently, studies done on commercial sized pine and spruce with a Canadian isolate of D. squalens under non-sterile conditions showed through-treatment (19 mm penetration) with 1.7% ACQ after six weeks in spruce samples; however, strength loss was slightly higher in some samples than what is found with conventional incising. Penetration was more variable in pine. A shorter incubation time would be desirable in an industrial setting. The current study was undertaken in order to determine if the processing time could be shortened by optimizing incubation temperature. Three temperatures were tested on small pine blocks using a soil block test method. Samples were exposed for between two and six weeks. ACQ-D treatment was used in this experiment as a surrogate for carbon-based preservatives because copper is easier to detect than colourless carbon-based preservatives. Optimal temperature for incubation appeared to cover a wide range around 30 °C and no growth inhibition was encountered at 35 °C suggesting that temperature variability in an industrial setting should not inhibit a biological incising operation. Uptake and penetration was variable. After 5 weeks seventy percent of pine samples reached a minimum of 5 mm penetration, and 50 % of the samples reached a minimum of 10 mm penetration. Optimal incubation time still appears to be over six weeks in pine to reach minimum 10mm penetration requirements in over 80% of samples.
Fungal infection of logs and lumber can occur in standing trees, and during harvesting, transport and storage. Such infections often appear as a visible discoloration of wood termed sapstain. This occurs predominantly on sapwood and is caused by a mix of bluestain fungi, moulds and/or decay fungi. Control of sapstain fungi can be achieved by rapid processing and kiln drying, or by using sapstain control products (antisapstain treatments). Sapstain control products are primarily intended to prevent new infections on green wood, and have limited capacity to arrest existing infections. The effect of pre-infection of logs or lumber on sapstain control product efficacy is poorly understood, and has been rarely investigated. Clear guidelines are needed on acceptable delay periods for log storage, or before sapstain control products are applied on lumber. Sawmill operators need to know the impacts of handling and storage practices to sapstain control product efficacy. The present work reviews the literature addressing pre-infection. In addition we compared the performance of fresh and pre-infected lumber in an antisapstain field test. In our experiment the sapstain control product at the highest (2 times recommended) concentration was generally able to control sapstain in freshly cut material. Incubation of pre-infected lumber for three days prior to the treatment was not associated with higher ratings (increase in visible fungal growth) in most samples. However, incubation of pre-infected lumber for seven days prior to the treatment was associated with increased surface growth by bluestain fungi. Under the conditions of this experiment a delay of one to three days before treatment application to lumber could be tolerated. However, there are numerous factors (e.g. local climate, degree of pre-infection, wood species, nature of chemicals applied) that may play a role in product efficacy, and it is not easy to pin-point an acceptable period between harvest and sapstain control product application. It is thus safest to apply sapstain control products with minimal delay.
Recent work suggested that near infrared (NIR) spectroscopy may be able to estimate extractive concentration in western redcedar (WRC) heartwood. This would facilitate the screening of breeding stock that will produce durable heartwood. Increment cores from 50 trees were scanned and analysed for extractives content to evaluate existing models. Extractives data were not accurately predicted by the developed models. This was likely due in part to the much smaller range of extractives in the increment core data set. Subsequent partial least squares (PLS) models based on the increment core data set confirmed that NIR is not sensitive enough to small variations in extractives to differentiate wood with small or medium differences in extractives content.
The present work also examined the ability of PLS models to predict decay resistance from NIR spectra. The developed models were not able to accurately predict weight loss caused by Coniophora puteana in a soil block test. Correlations between extractives data and decay resistance data were very weak. This weakness may have been exacerbated by the leaching and biodegradation steps that would have reduced the concentration of thujaplicins in the samples.
The long-term performance of carbon-based preservatives may be limited by detoxification by microorganisms. This study identified primary colonizers of wood treated with carbon-based preservatives that may contribute to detoxification of carbon-based biocides. Wood coupons treated with three different carbon-based preservatives were subjected to a repeated wetting and drying cycle in an accelerated field simulator for 2, 4, 8, 16 and 32 weeks. After exposure, samples were analysed for triazoles or DDAC concentration and microorganisms were isolated and identified using culturing onto malt extract and Luria Bertani media followed by DNA extraction and sequencing of representative isolates. Bacteria from the genus Pseudomonas were found on all three treatments at all sampling times. Few fungal isolates were obtained; one isolate was identified as a Trichoderma sp., while the remainder were identified as a Penicillium species. The data indicated a possible succession in species that may be caused by the change in amount of active preservative remaining in the samples over the duration of the experiment. No difference was observed in bacterial colonization based on the preservative used in the experiment. Future work should focus on determining the role of Pseudomonas in preservative detoxification, and finding preservative formulations capable of inhibiting colonization by Pseudomonas.
The apparent inability of carbon-based preservatives to move into and protect checks exposing untreated wood in service means it may be more important to achieve deep penetration with these preservatives. The work reported here builds on previous research which examined the effect of a range of pressure treatment process modifications and formulation additives to improve the penetration of borate- and copper-based preservatives. The effects on penetration of carbon-based preservative of six process variables and three additives were evaluated in the new, insulated stainless steel retort. Fluctuating pressure around a set point did not improve uptake or penetration. Increasing solution temperature showed improved uptake, but did not improve penetration. This was likely due to the increased fixation rate of the DDACarb/Amine oxide. Steaming before treatment in kiln or in retort impeded uptake and penetration. Steaming after treatment also did not show improvement over the standard treatment. Adding ethanol did not improve uptake or penetration. CCA reference treatment showed the greatest uptakes suggesting that the carbon-based preservative may have a negative effect on uptake. Adding DOT at 0.5% to the treating solution showed an improved uptake of 16%, but penetrations were less than the standard treatment, possibly due to stripping of the amine oxide during previous treatments. This requires further investigation. Comparing the penetration of borate and DDACarb/Amine-oxide showed that the DDACarb/Amine-Oxide component of the treating solution was being stripped out of solution as the formulation penetrated the wood. Additive A showed the most promising improvements increasing edge penetration by 16% and increased heartwood face penetration by 22%. This treatment had 85% of the samples greater than or above 5mm surpassing the CSA standard for residential product group C, without incising.
The work in 2011/2012 on phytosanitary measures had several significant positive outcomes. Most importantly, we provided contributions to the work of IFQRG which is a key forum for critical discussions on proposed new regulations and phytosanitary treatments options. IFQRG also advises international bodies that are directly involved in phytosanitary policy/standards making.
Because of the location of this year’s IFQRG meeting (Canberra) there was a significant presence from Australia/New Zealand regulators at the IFQRG meeting. They often push for the most stringent and trade-damaging phytosanitary regulations that are often followed by other countries in the region. At the meeting they realized the value, the merit, and transparency of the IFQRG activities and are likely to trust the IFQRG process, and to participate in and follow its recommendations in the future.
IFQRG made a significant step in simplifying the requirements for new treatment efficacy data after being asked specifically by the Standards Committee (SC). It has never happened before that the SC has given such credibility to IFQRG to influence policy making. A small group including Adnan Uzunovic recommended and drafted a simplified three-step process with only seven test pests (instead of an unspecified and endless list of pests and life stages of pests) to be tested in the first step followed by testing the most tolerant pest in step 2 and 3. We also provided arguments why we need to get away from Probit 9 requirements that were stalling new treatment development. A large majority of IFQRG members were very supportive of this approach and it is hoped that the Standards Committee (SC) and Commission on Phytosanitary Measures will use our suggestions to adjust the current text in the standard.
In April 2011 the SC approved the draft of a rapid dielectric heat treatment method (that included FPInnovations efficacy data against PWN) as a potential new treatment for wood packaging and sent it for member country consultation. Several members supported this treatment being adopted as soon as possible while some members requested more operational guidance for commercial facilities. Adnan took an active role in discussing these issues to support the MW/RF technology adoption and will be included in teams that will develop guidance documents and generate additional information if needed. This may bring additional opportunities to continue filling gaps on dielectric heating and through additional funding and collaboration.
The opportunity arose to share our expertise on bluestain with Australian regulators, encouraging them to re-assess their attitude towards bluestain fungi as quarantine organisms and argued against incinerating or returning lumber shipments lumber with live bluestain. Adnan suggested that current data do not support the attitude of labeling bluestain fungi as quarantine organism and shared information we know about bluestain fungi in the context of pathogenicity to trees. In similar way we headed off publication of a paper that would have equated live bluestain with pathogenic fungi and hopefully continue to maintain a $173.5 million market for green lumber exports to Japan.
On the potential increase of required heat treatment from 56/30 to 60/60 or 71/70, IFQRG further discussed this issues and maintained its stand that heat treatments as described under ISPM-15 (bark removed, 56/30 heated to the core) continue to be appropriate to sufficiently reduce the risk of Emerald Ash Borer and other pests.
Adnan gave four presentations at IFQRG, establishing an image of FPInnovations as a capable, independent, and unbiased research provider that can, in parallel, work with fumigants, dielectric heating, molecular genomics, develop and carry out standardized test protocols, and provide advice and research data to its government and policy makers. Our participation was commended by IFQRG chairman as an important asset to the group, sharing a rare mix of: good science background, careful hard work, and being knowledgeable and also very aware of practical considerations and potential repercussions for the industry and trade.
Together with Pennsylvania State University and USDA colleagues we visited BOC International Ltd. (the official name of the multinational industrial gas company that is now a part of The Linde Group) and discussed potential work with ethane dinitrile (EDN), which currently is the most promising alternative gas to methyl bromide for quarantine treatments, but lacks efficacy data in North America. There was a great chance of receiving additional funding from BOC or USDA in 2012 to carry some of that work at FPInnovations. CFIA and Canada Wood are also aware that FPInnovations is best positioned to do this required work and would additionally support us. However in January 2012, we were told that BOC had decided not to provide EDN gas to any outside research organization at this stage.
Field tests of wood coatings in Maple Ridge, BC and Saucier, MS were evaluated. Coatings on spruce heartwood generally performed better than those on pine sapwood. All preservative treatments were associated with improved performance of coatings F1 and F3. Coating F2 was so degraded that there were no apparent differences. All of the protective pre-coats were associated with better coatings performance. In addition, pre-treatment with various plasmas was associated with better coatings performance, similar to that obtained with the protective pre-coats. Colonisation by black stain fungi was the predominant mode of failure for all coating at both test sites. Samples coated with F2 and F3 have largely failed; however, many samples coated with F1 are still in good shape. Samples coated with F1 should be re-evaluated after 36 months of exposure to improve estimates of service life and enable a full cost benefit analysis of these technologies.
Programme des technologies transformatrices ; Projet TT.4.3.03
Une analyse du cycle de vie de la palette de bois feuillus produite dans l’Est du Canada en 2008. L’analyse portait sur l’ensemble des phases du cycle de vie de l’extraction des ressources jusqu’à la fin de vie en passant par la fabrication des palettes. L’analyse repose en majeure partie sur des données primaires provenant de trois usines du Québec et du Nouveau-Brunswick dont la production combinée représente environ 10 % de la production canadienne de palettes de bois feuillus.
Programme des technologies transformatrices ; Projet TT.4.3.03
L’objectif de ce projet était d’acquérir des connaissances sur les problèmes de fausse détection occasionnés par l’oxydation et la présence de marques ou d’impuretés sur la surface des sciages bruts à l’état vert lors du scannage.
Les tests ont permis d’identifier douze différents types de marques ou impuretés de surface qui pourraient biaiser la décision des systèmes de vision. Selon les procédés de fabrication et les équipements utilisés, on les retrouve sur 17 % à 80 % des sciages produits en scierie. Les impuretés les plus fréquemment observées sont les marques de chaines, la présence de sciure et les marques causées par le contact des scies avec un nœud contenant de l’écorce ou de la carie. À eux seuls, ces trois types d’impuretés comptent, dans certains cas, pour plus de 93 % des marques identifiées.
Ces types d’impuretés n’ont pas tous la même influence sur la performance d’un système de vision. Certaines marques sont filtrées adéquatement et n’ont aucune répercussion sur la décision de scannage alors que d’autres sont perçues comme des défauts ou camouflent un défaut existant, ce qui a pour conséquence de déclasser ou de surclasser les sciages.
L’impact des fausses détections sur la valeur des sciages diffère énormément selon le nombre et la catégorie d’erreurs ainsi que la qualité initiale des sciages affectés par les impuretés. Certains types d’impuretés ont conduit à des pertes de 446 $/Mpmp alors que d’autres ont entraîné des gains de 9 $/Mpmp. Lorsque pondérées, ces fausses détections représentent pour une scierie un manque à gagner annuel pouvant atteindre 250 000 $, si aucune mesure corrective n’est prise pour remédier à la situation. À cet effet, des pistes de solution visant à éliminer ou à limiter les marques ou impuretés à la surface des sciages sont décrites dans ce rapport.
Quant à l’oxydation, les tests effectués durant l’hiver démontrent qu’à l’intérieur d’une période approximative de 24 heures, la coloration qui en résulte n’est pas assez importante pour modifier la décision du système de vision. Nous suggérons que d’autres tests soient effectués pour connaître l’impact de l’oxydation dans des conditions différentes.
Element 4 : Hardwood initiative - Development of new processes and technologies in the hardwood industry : Best practices to avoid hardwood checking. Part 1. Hardwood checking - the causes and prevention
Transformative Technologies Program ; Project No. TT4.3.03
Wood checking is a major problem that has a significant economic impact for hardwood producers and consumers. Wood checking can occur on logs, green lumber, dried lumber and final products during manufacturing, drying process, storage and end-use. Checking on wood products is caused by many internal and external factors such as wood species, moisture content, storage method, drying process, temperature, relative humidity, air flow velocity and solar radiation. While it is impossible to completely eliminate wood checking; it however can be controlled to an acceptable level with proper measures. The control measures include best practices in harvesting, storage, sawing, drying, chemical coatings, physical methods and controlling end-use environmental conditions. This report provides scientific information on the nature of different types of checks that may occur on various wood products, checking conditions and control measures.
It is not surprising to see a rapid growth in the demand for mid- to high-rise buildings. Traditionally, these types of buildings have been dominated by steel and concrete. This trend creates a great opportunity for wood to expand its traditional single and low-rise multi-family building market to the growing mid- to high-rise building market. The significance and importance of wood construction to environmental conservation and the Canadian economy has been recognized by governments, the building industry, architects, design engineers, builders, and clients. It is expected that more and more tall wood frame buildings of 6- to 8-storeys (or taller) will be constructed in Canada. Before we can push for use of wood in such applications, however, several barriers to wood success in its traditional and potential market places have to be removed. Lack of knowledge of the dynamic properties of mid- to high-rise wood and hybrid wood buildings and their responses to wind, and absence of current guidelines for wind vibration design of mid- to high-rise wood and hybrid wood buildings are examples of such barriers.
This report summarises results from the first year study of this project and from other two one-year related projects. The main objective of the study was to build a framework for the development of design guide for controlling wind-induced vibration of mid- to high-rise wood and hybrid wood frame buildings, to ensure satisfactory vibration performance during high winds.
A literature review of the existing database of the dynamic properties of 1- to 3-storey wood platform buildings was conducted. The test system and protocols of ambient vibration tests (AVT) was developed. Collaboration with McGill University was also established to verify the AVT system and the test protocols. AVT tests were conducted on two 2-storey non-residential hybrid heavy timber platform buildings, three new heavy timber (glulam) non-residential buildings of 4-6 storeys and on two cross-laminated timber (CLT) condominium buildings of 3 and 4 storeys. The monitoring system to determine the vibration response in wind of mid-to high-rise wood frame building was developed. The database consisting of the data in the literature and our measured fundamental natural frequencies of the wood frame building were used to verify the NBCC equations to estimate building fundamental natural frequencies. Collaboration with Tongji University was established to explore the potential use of the finite element commercial software Ansys, for simulation of vibration performance of wood frame buildings.
It is concluded that the project was on the right track towards the development of a design guide for controlling wind-induced vibrations of mid- to high-rise wood frame buildings. The results from this study and other two relevant projects confirmed that AVT and computer simulation are useful, and appropriate tools for the development of solutions and a design guide for controlling wood frame building vibrations in wind.
It is recommended that current NBCC equations using building height as a variable to estimate the building fundamental natural frequency can be used to predict the fundamental natural frequencies of wood frame buildings, until a better calculation methodology is developed. More field data of the fundamental natural frequencies measured on mid- to high-rise wood frame or hybrid wood buildings are needed to further verify the NBCC equations, or to develop more suitable equations for wood buildings.
In the built environment wood surfaces often experience different exposure conditions, particularly exposure to sunlight. This can result in part of a surface receiving full sun, while other parts may be completely shaded. Methods that minimize the resulting colour differences between exposed and shaded areas would enhance the aesthetic appeal of wood. In the present work a “pre-weathering” approach to wood colour stabilization was investigated. After two months of natural exposure, colour change was similar regardless of pre-exposure. The heartwood samples in a shade exposure were much more discoloured than the equivalent sapwood samples. This suggests that heartwood extractive oxidation is a major cause of initial heartwood discolouration. The samples exposed to the sun did discolour more, indicating a UV/Visible light effect as well.
A new design Section on Lateral Load Resisting Systems (LLRSs) was introduced in the 2009 edition of Canadian Standard for engineering Design in Wood (CSA O86). The activities presented in this report (development of technical papers, development of technical polls and attending various code committees) have a goal to continue the work in this field by further improving the new Section on LLRSs by implementing additional design information for other wood-based structural systems and assemblies. During the last two years, several technical polls and papers were developed and presented to various code committees for future code implementation. These activities will help design engineers to use timber in structural systems in residential and non-residential buildings in Canada and the US.