Ce rapport décrit les résultats d’études en cours ou antérieures réalisées par Forintek sur les méthodes utilisées pour l’aboutage du bois et la qualité des produits. Il donne une description détaillée des différents paramètres susceptibles d’affecter le procédé d’aboutage et la qualité du produit fini. Il contient également une masse de renseignements publiés dans le cadre d’ateliers, de conférences ou de revues techniques. Cette information a été regroupée et intégrée dans un format simplifié de façon à être utilisable dans la fabrication des bois aboutés. L’un des chapitres porte sur le processus de qualification et de contrôle de la qualité des bois de charpente aboutés et décrit les normes canadiennes de produits spéciaux applicables. On trouvera à la fin de chaque section un paragraphe traitant d’idées de recherche novatrices, de questions importantes pour l’industrie canadienne du bois abouté et de lacunes dans les connaissances.
In this study builders and professional repair and remodellers were given a chance to evaluate 12 of the most common home siding products available in the market today. The products were evaluated on seven different attributes: price, maintenance, installation, attractiveness, status/image, fire resistance, and durability. Overall, fire resistance, attractiveness, and maintenance were selected as the most important product attributes by single-family homebuilders and repair & remodellers. The majority of respondents stated that their customers had a strong influence on their final choice of siding materials. In addition respondents were asked for their opinion regarding product popularity, rate of installation, substitution trends, and their choice of siding products for different categories of homes.
The market for hardwood component production is currently affected by low-cost components importation from Asia. Industrial automation is an actual option for the secondary manufacturing industry to counter this situation. Integrating a defect detection system is a complex process and selecting the right system is even more complicated. This study proposes an approach for assessing the defect detection capabilities of different systems as well as a decision support tool to guide the producer toward the adequate equipment. The study is limited to assessing defect detection capacities; the overall system performance, the optimization software and the cutting equipment are not analyzed.
Understanding the origin and characteristics of defects to be detected and the capacities and theoretical limits of vision technology are prerequisites. A sampling with defects that, due to properties such as their small size, are hard to detect, is assessed by each system and the results are compared. To date, the assessed systems are not capable of detecting all defects pertaining to hardwood component production. A decision support tool will make it possible to methodically select the equipment most appropriate to the producer’s needs and leads to an enlightened decision in terms of the producer’s priorities and expectations.
This report summarises progress in the second year of this project. Significant progress has been made towards achieving the original objectives of the project. In addition, several other applications of fire models have been identified that would further the interests of the Canadian wood industry and so appropriate research was initiated.
An objective of this project was to identify wood-stud walls that qualify as being of fireproof construction in Japan. To be classified as fireproof construction, a wood-stud wall must pass the 1 + 3 test in which it is subjected to a one hour fire-resistance test and then must support its load for another 3 hours as the furnace cools. Attempts were made to revise WALL2D to model the response of walls during the heating and cooling phases of an arbitrary fire. The revised model was to be used to model the response of walls in the 1 + 3 test and in furnished house fire tests run in Kemano. However, it turned out to be a major revision to include a cooling phase in WALL2D, but revisions were made to model a heating phase of an arbitrary fire. This was sufficient to get good agreement with temperatures measured within walls in Kemano. Revision of WALL2D to model the 1 + 3 test has been deferred until 2004-2005.
The Japan 2 x 4 Home Builders Association and the Council of Forest Industries have identified, by testing, wood-stud walls and wood-joist floors that pass the 1 + 3 test. These assemblies have been granted Ministerial Approval as being of fireproof construction. It is therefore possible to build 4-storey wood-frame apartment buildings in high-density urban areas. Employing models to identify assemblies that pass the 1 + 3 test is now less urgent, but will continue as models may suggest ways to optimise assemblies meeting the 1 + 3 test.
Another objective of this project was to undertake performance-based design of a building as a showcase study. Carleton University is developing a model to evaluate fire safety designs for 4-storey wood-frame commercial buildings. The first building to be analysed is a wood-frame version of the Carleton Technology Training Centre. The Carleton University model does not yet model the response of the structure of the building. To supplement Carleton University’s efforts, Forintek will undertake performance-based design for fire resistance of a wood-frame version of this building in 2004-2005.
While the initial completion date for this project was to be March 2004, it was intended that if other applications of fire models were identified that would further the goals of the Canadian wood industry, the project would be extended. During 2003-2004, several new applications of fire models were initiated:
A fire resistance model developed jointly by Forintek the National Research Council Canada is being employed to estimate the impact on fire-resistance ratings of the load applied to wood-stud walls during a test. This information would be useful when quoting the fire-resistance ratings of Canadian assemblies in export markets where lower loads are applied during fire tests.
A collaborative venture has been initiated with Australian researchers to model fires in large compartments (found in non-residential buildings) and the resultant response of wood-frame walls.
Data generated in fire tests conducted in furnished houses in Kemano is being used to assess the ability of current fire models to predict fire development in these houses and to predict the performance of a variety of building assemblies. If the models do a good job, one would have increased confidence in applying fire models in a performance-based design environment.
To demonstrate the good fire performance of wood-frame assemblies, three fire tests were run for visiting Chinese fire experts. Fire models were used to design the experiments to ensure that wood-frame assemblies were selected that could withstand the fire exposures envisioned in the tests.
Lors de la conception des structures en bois d’oeuvre, il importe que les éléments de la charpente, telles les poutres, les colonnes et les fermes, soient conçus de manière à résister aux charges prévues, puisqu’une chaîne n’est jamais plus forte que son maillon le plus faible. Il est tout aussi important que les assemblages de ces éléments soient conçus avec soin. Un assemblage doit pouvoir transmettre la charge et ses contraintes, d’un élément à un autre, en respectant des limites acceptables de déformation. Le rendement adéquat de l’assemblage importe particulièrement dans le cas des structures construites dans les régions sismiques, où la défaillance d’un assemblage peut entraîner l’effondrement de la structure lors d’un séisme important. L’introduction de divers produits du bois sur le marché a accru les occasions d’utiliser le bois dans diverses applications structurales, ajoutant ainsi à l’importance du rôle des assemblages dans les éléments structuraux.
As this is a relatively new field much of the emphasis of this study was on a literature review to help develop a theoretical platform to work from. It was found that the colour of wood appears in the literature in two ways. It appears qualitatively in marketing and value-added research, and it appears quantitatively in colour matching and quality control research. The present research study is the first known occurrence of the quantitative comparison of measured colour with measured consumer preference.
There has been considerable research into character marks in wood. This research has largely been based around traditional hardwoods as the result of increasing scarcity of high grades of lumber. However, more fundamental characteristics such a grain profile, rings per inch, and the presence of visual features such as rays and vessels have not been considered with respect to visual preferences.
Consumer preference data used for this study originated from the study “Consumer visual evaluation of underutilized Canadian wood species” (Fell, 2002). This was chosen as it has a great variety of species to analyze. However, in the survey consumers evaluated the species for overall appearance and not for specific end-uses. Therefore results of the current study are general to wood used in the home and do not apply to specific end-uses.
The consolidation of the homebuilding industry is meant to continue and to have profound impacts on the forest products industry. It is changing the way houses are built as well as the relationships between building materials suppliers and home builders. Along the consolidation way, builders are also gaining more purchasing power as evidenced by the lumber consumption of the Top 100 builders, estimated to near 7 billion Board Feet.
More than ever before, large homebuilders are considering direct and longer term agreement with suppliers of lumber and OSB. It is expected that, due to the emergence of longer term and more direct purchasing agreement, collaborative practices become more developed. As far as building techniques go, we assume that the componentization of the housing industry will keep its advance, especially in the large builder segment. Componentization not only brings more off-site fabrication, but it also relies on a higher engineering content in the housing construction process.
Currently, purchasing agreements are short term based either for lumber, structural panels, engineered wood products, roof trusses and prefabricated walls. However, when questioned about the future of their purchasing agreements, respondents clearly showed a propensity to develop long term agreement. Indeed, every participant to this study pointed out to longer term agreements with suppliers and, in some cases, raised the possibility of more exclusive arrangements. This observation was further confirmed in site visits.
While centralization of the purchasing process is not the preferred choice of every large builder, we hypothesize that the specifiers will increasingly be centralized in the future in the wake of national purchasing agreements. Meanwhile, it is clear that regional offices will continue to have their word to say. Materials selection is not a one way process from top to bottom, but the head office is likely to be involved even when the process is regional.
As of now, most of the interactions between large builders and their suppliers may be summarized as information exchange. This indicates a fairly low level of inter-firm co-operation. However, the majority of participants expect either a shorter supply chain, more direct relationships or more partnering over the next five years. In turn, information and communication technologies, either for fund transfer of business planning, will spread out.
Ce projet de recherche sur l’automatisation des procédés dans l’industrie des maisons préfabriquées, plus précisément la fabrication de murs fermés prêts pour l’installation sur le chantier, permet de documenter et de planifier une amélioration de productivité dans les usines déjà existantes ou encore à déterminer quel type d’usine il faudra établir en fonction du potentiel annuel de ventes de maisons préfabriquées.
Les résultats de ce projet sont présentés dans ce rapport. Des scénarios sont élaborés suivant divers degrés d’automatisation manufacturière. Les résultats démontrent que, suivant le marché de l’industrie de la maison préfabriquée, diverses options sont à la portée des manufacturiers.
Ce rapport intéressera les manufacturiers existants de même que ceux en devenir; car il donne un aperçu d’automatisation pouvant être apporté dans une usine de préfabrication.
This benchmarking study aims at providing the Canadian industry, agencies and governments with the necessary understanding of the knowledge and perception of wood roof trusses among specifiers in selected urban regions in China for ongoing and future promotions of wood roof trusses in China.
The objectives of this project are the following:
1. Assess current awareness, knowledge and perception of wood roof trusses in multi-family housing among specifiers (architects, engineers and builders/developers);
2. Examine how decisions on roofing/building systems and materials are made;
3. Determine best ways to transfer knowledge about wood roof truss systems to specifiers.
Two separate surveys were carried out for benchmarking wood use in roofs in China. The first survey was part of a survey of Chinese building specifiers (Benchmarking Chinese Building Specifiers (Cohen and Ding 2004)) carried out in October/November 2003. A second survey was administered during the Conference on Hybrid Building Construction in China and Wood Roof Truss Workshops in Shanghai and Beijing in December 2003.
Oriented strand board (OSB) is widely used in house construction in North America. In Canada, OSB panels are commonly made of aspen strands and are susceptible to mould and decay when they get wet. Building envelope failures due to mould, decay or poor construction practices can negatively impact the image of wood. This can lead to product substitution that in turn can affect the wood industry’s overall competitiveness. To ensure durability of OSB panels, the most important consideration is the use of mould- and decay-resistant panels to prevent fungal attack. Using low environmental impact technology to improve the durability of OSB products could have market-related advantages over using chemical protection products. This project aimed to develop technologies for protecting OSB raw materials from biodegradation and to explore biological pre- or post-treatments to increase the durability of panels so they would better resist mould, stain and decay.
The project was divided into three parts. Part one involved developing a biological technology to protect OSB raw materials from biodegradation. In this part, aspen, red maple and yellow birch trees, which are commonly used to make OSB in Canada, were felled in May and cut into 4-foot logs. These logs were then equally divided into two groups (16 logs each) with one group keeping its bark and the other having it removed. These debarked and “bark-on” logs were further divided into two groups, each containing 8 logs. One group of logs was treated with a bioprotectant and another group served as a control. The treated and untreated logs were stored separately in Forintek’s yard. Two inspections were conducted, one at the end of the growth season (in October after a 5-month storage period) and the other after one year. During each inspection, four logs from each test group were examined for fungal degradation (mould, stain and decay), and then cut into strands to be used for manufacturing panels. The panels’ physical and mechanical properties and mould resistance were evaluated.
The second part involved developing a biological pre- or post-treatment technology by using naturally resistant wood species to increase the durability of panels so they would better resist mould, stain and decay. In this part, a series of tests were conducted using various wood species. These tests included a) determining the antifungal properties of bark from various wood species; b) using white cedar to improve panel durability; c) optimizing manufacturing conditions for producing durable panels with white cedar; d) using other wood species to produce mould-resistant panels; and e) post-treating panels with extracts of durable wood species.
The third part consists of developing a biological pre- or post-treatment technology by using fungal antagonists to increase the durability of panels against mould, stain and decay. This part will be conducted in the 2004-2005 fiscal year, and results will be included in next year’s report.
The results of the first part on the protection of raw materials showed that all untreated logs, with or without bark, were seriously degraded by moulds, stain and decay fungi after a summer storage period of five months. The logs with bark were more degraded than the debarked logs, and the log ends were more degraded than the middle sections. After summer storage, 55% to 83% of the wood was degraded in untreated logs. The biological treatment was effective, only 4% to 16% of the wood in treated logs was affected by various fungi after a five-month storage period. Furthermore, the biological treatment was more effective on logs without bark than logs with bark, and more effective on yellow birch and aspen than on red maple. After one year in storage, the total infection rates of untreated logs ranged from 68% to 91%, whereas the rate for biologically treated logs ranged from 27% to 49%. Among these treated logs, the logs ends were degraded from 31% to 62%, whereas the middle sections were degraded from 7% to 26%. Strands cut from untreated logs contained 50% to 75% of grey or blue stained strands, whereas those cut from biologically treated logs contained 10% to 25% of such strands. Panels made using biologically treated logs had the lowest TS and WA values compared with panels made using fresh-cut logs and untreated stored logs. The other physical and mechanical properties of the various panels made for this test were comparable.
The antifungal properties of bark from six wood species (aspen, red maple, yellow birch, balsam fir, white spruce and white cedar) were investigated in the second part of this research project. Based on the colony growth rate of moulds, stain and decay fungi on bark-extract-agar media, white spruce bark was the best at inhibiting growth of these fungi, followed by red maple bark. White cedar and balsam fir bark somewhat inhibited certain fungi tested. Aspen and yellow birch bark did little or nothing at all to inhibit fungal growth. The research also showed that the white cedar heartwood-extract-agar medium not only inhibited decay fungi growth, but also inhibited the growth of moulds and staining fungi. The bark-extract-agar medium of this wood species was less effective in inhibiting fungal growth than the heartwood was.
Three-layer panels made using white cedar heartwood strands in the face layers and aspen strands in the core layer at a ratio of 25:0:25 were mould and decay resistant, but the panels “blew” easily during manufacturing and their mechanical properties were not satisfying. The overall mould infection rate on white cedar heartwood-faced panels was 0.8, which indicated that the panel was mould resistant. White spruce heartwood-faced panels were highly mould resistant and moderately decay resistant. The overall mould infection rate on white spruce heartwood-faced panels was only 0.2 after 8 weeks of exposure to high humidity environmental conditions. In addition to being mould resistant, white spruce heartwood-faced aspen panels also had better IB, MOR and MOE properties, compared with aspen panels. The panels with black spruce in surface layer had mechanical and mould-resistance properties that were similar to those with white spruce in surface. The panels with surface layer of Eastern larch heartwood were non-resistant to moulds and slightly resistant to decay, but they had better IB, TS and WA properties compared with the other types of panels. The overall mould infection rate on the panel with surface layer of Eastern larch heartwood was 3.7, which was similar to the rate for aspen control panels. Aspen panels (serving as control panels) were seriously affected by moulds with overall mould infection rates ranging from 3.8 to 4.9.
Aspen panels with surface layer from whole-wood strands (using both sapwood and heartwood) from white cedar, in a ratio of 25:50:25 and pressed at 220°C for 150 seconds, were well bonded and had IB, TS, WA and MOE values that were similar to those of aspen control panel, but with a higher MOR. All the panels’ properties met the requirements of the standard. This type of panel also was the least infected by moulds, especially in the face layers which rated a 0.2. The panel sides were moderately infected, rating a 2.6, this occurring mostly in the middle layer of aspen strands. The overall rate of this type of panel was 1.0, which indicated that the panels were resistant to mould infection. This type of panel was also highly resistant to brown rot and moderately resistant to white rot.
Panels made of steam-treated white cedar whole-wood strands and aspen strands at a ratio of 3:7 based on oven-dry weight also had low infection rates: the average face infection rate was 1.2; the side infection was 2.4 and the overall rate was 1.6. Compared with aspen panels, this type of panel also had high MOR and MOE values and low TS and WA values.
In the case of white cedar whole-wood strands faced aspen panels, when the pressing time was increased from 160 seconds to 180 seconds at 200°C, the panels’ IB strength and MOE increased whereas the panels’ TS, WA and MOR decreased. By increasing the pressing temperature from 200°C to 240°C and pressing for 160 seconds, the panels’ IB strength, MOR and MOE increased and the panels’ TS and WA decreased sharply. At a pressing temperature of 240°C and a pressing time of 180 seconds, the panels’ IB strength, MOR and MOE increased significantly and the panels’ TS and WA decreased significantly. These data showed that aspen panels with surface layer from white cedar whole strands at a ratio of 25:50:25 and pressed at 240°C for 180 seconds had the best mechanical and physical properties. All panel samples were slightly infected by moulds on the faces. A fair amount of mould occurred on the sides of panels pressed at 200°C for 160 seconds and 180 seconds and those pressed at 240°C for 180 seconds. The panels pressed at 240°C for 160 seconds were the least infected by mould (with an infection rate of 0.3). Panels pressed at 200°C had a white-yellowish colour, whereas those pressed at 240°C were yellow-brownish and darker than those pressed at 200°C. Panels pressed at 200°C for 160 or 180 seconds and those pressed at 240°C for 160 seconds were highly decay resistant, especially to brown rot. The decay resistance of panels pressed at 240°C for 180 seconds was lower compared with the other panels.
Compared with aspen panels, panels with surface layer from steam-treated white cedar strands and aspen strands at a ratio of 7:3 based on oven-dry weight had higher TS, WA, MOR and MOE values and a similar IB value. Panels with surface layer from steam-treated white cedar strands and aspen strands at a ratio of 4:6 based on oven-dry weight had the highest IB value. A reduction in mould and decay resistance corresponded to a reduction in the proportion of white cedar strands in the face layers. The overall mould growth rate was 1.27 on panels with surface layer from steam-treated white cedar strands and aspen strands at a ratio of 4:6, 0.6 on panels with surface layer from steam-treated white cedar strands and aspen strands at a ratio of 7:3, and 0.4 on panels faced with 100% white cedar whole strands, respectively.
Panels made from 100% white cedar whole-wood strands or a mixture of whole-wood strands of white cedar and aspen (50:50) in the core layer were “blown” after pressing. Panels made from a mixture of white cedar and aspen strands at a ratio of 25:75 in the core layer and aspen strands in the face layers had superior IB, MOR and MOE values than other panels. However, their TS and WA values were also higher than those of white cedar-faced panels. Panels made from a mixture of white cedar and aspen strands at a ratio of 25:75 in the core layer and white cedar strands in the face layers had the worst physical and mechanical properties among all the panels made for this test. The tests results for mould showed that panels made with a mixture of white cedar and aspen strands at a ratio of 25:75 in the core layer and aspen strands in the face layers ware seriously attacked by moulds and had an overall mould growth rate of 4.2. No mould infection was found on panels made from 100% white cedar strands. Panels made from a strand mixture of white cedar (50%) and aspen (50%) in the core layer and white cedar strands in the face layers had little mould infection. The overall mould growth rate on this type of panel was 0.2.
Compared with the control aspen panels, aspen panels with surface layer from white cedar whole-wood strands at a ratio of 15:70:15 had similar IB and TS values, a lower WA value and higher MOR and MOE values. When the white cedar strand proportion in the face layer was increased from 15% to 25%, the panels’ IB strength and WA decreased, but their MOR and MOE values increased. Panels with surface layer from white cedar strands at a ratio of 15:70:15 had little infection from moulds on the face and bottom layers, but had an increased infection rate on all four sides. The average overall infection rate of this type of panel was 0.5. When the white cedar in the panels’ face layer was increased from 15% to 25%, the average infection rate on the panels’ faces was still 0.1, but the infection rate of the panels’ sides dropped from 1.2 to 1.0. The overall rate was 0.4. In terms of decay resistance, panels with surface layer from 25% white cedar strands performed better than those with surface layer from 15% white cedar.