This report summarises the work accomplished in this one-year project in which the fire performance of wood-frame buildings was to be documented. A detailed analysis of Canadian and American fire loss statistics for residential occupancies was undertaken in order to assess the impact of the choice of building materials and the nature of fire-safety provisions in building codes on the overall fire safety in buildings. It was expected that the knowledge gained would enable the wood industry to argue more effectively during deliberations of codes and standards committees.
This study demonstrated that buildings constructed in compliance with current North American building code requirements are among the safest in the world. It was found that the fire loss record of wood-frame houses is about the same as that of large apartment buildings of non-combustible construction. It was shown that the ignition of upholstered furniture or mattresses by smokers’ materials is far and away the leading cause of residential fires involving deaths. Most of these deaths occur before the structure of the building becomes damaged by or involved in fire. Enacting more stringent building code requirements is unlikely to pay a large dividend in terms of life safety. In fact, the statistics suggest that significant improvements in fire safety in buildings would be more easily achieved by limiting the flammability of upholstered furniture and mattresses.
The purpose of this study is to investigate and record the principal problems associated with chipped surface quality at canter lines and evaluate degrade and value losses due to these problems.
Mill measurements were conducted in five member sawmills in British Columbia to evaluate the value losses and lumber degrades due to chipped surface defects. The test lumber was sampled from the planing mills to identify the chipping losses and main problems. The five types of chipped surface defects influencing lumber grade are: knot tear-out; failure to remove chipped spline channel; torn grain without knots; scalloping; and chipped thin end.
Average value losses for all mills were $11.4/MBF and $12.6/MBF in freezing and non-freezing conditions respectively. Removing the non-freezing data from one mill changed this to $11.4/MBF and $9.0/MBF respectively. Knot tear out caused 60% of lumber to be degraded. On average, over 55% of knots had tear-out. 42.3% of trim length was caused by failure to remove chipped spline channel.
Canada is one of the largest exporters of forest products in the world. To develop and transfer low environmental technology to eliminate wood infection is one of Forintek's program goals, and biotechnology is one of such technology. The application of biotechnology in forestry and wood protection has been explored to a limited extent worldwide. In order to allow the Canadian wood industry to take advantage of this enabling technology, this report summarizes various activities conducted by Forintek to stimulate the development and application of biotechnology for wood protection in Canada. The report also intends to review previously published researches on the use of biotechnology in wood protection. It will discuss the potential benefits and challenges to the applications of biotechnology in this area. It will cover the needs and opportunities of linking biotechnology and wood pest control. The future trends of the research and development will be discussed. In the last section, recommendations will be made to Forintek for devising a vision of the application of biotechnology in wood protection.
Wood is a renewable resource and plays an important role in the world economy; however, it is subject to attack from wood-degrading fungi and insects. In Canada, it is estimated that about 10 million m3 of softwood lumber is treated with anti-sapstain chemicals annually, and around 4% of the wood products are preservative treated against decay and termites. Biotechnology may help in developing more effective and low environmental impact technologies for wood pest control. In wood protection, biotechnology currently has applications in wood durability improvement, in genetic engineering for wood pest resistance, in biological protection of wood against insect, stain and decay damage, and in detection and diagnosis of wood sapstain and decay infection.
The future application of biotechnology to wood protection is likely to focus on the development of diagnostic kits for wood degrading fungi, commercialization of bio-pesticides against fungal degradation, wood surface modification by enzymes, and genetic engineering of trees for durability.
The key challenge faced by the Canadian biotechnology industry in the development and the use of biotechnology-derived products and processes of wood protection is the bio-product registration. Public attitude against the environmental release of genetically engineered organisms may also have a strong effect on the development of these bio-products.
It is recommended that Forintek take the following roles in the future development of biotechnology in wood protection: a) to provide the knowledge base and the technology to contribute to enhanced tree breeding processed for wood durability; b) to develop safe and effective deployment strategies for sapstain and decay control biotechnology-derived products; c) to provide the knowledge base and the technology for more energy efficient and environmentally friendly wood protection processes; and d) to foster the acceptance of forest biotechnology by the Canadian wood products manufacturing industry.
The objective of this project was to provide a baseline evaluation of the market fit of new and existing structural floor systems in residential construction. The project focuses on the attributes that are demanded by specifiers of floor systems and the tradeoffs made among attributes when designing and building these systems. This information will aid product manufacturers and the research community in better meeting market demands.
The project identified specific attributes that are being demanded of floor systems (including ease of design, ease of construction, costs, safety factors, serviceability, performance, durability, indoor air quality, and walking comfort), and evaluated the trade-off made among these attributes in design/construction. The latter was accomplished through a mail survey of single-family homebuilders throughout North America. Finally, the homebuilders that filled out the survey were asked to offer a detailed description of the installed floors in the last house the built in 1999.
The results showed that the respondent homebuilders the three most important floor attributes are, in order, dimensional stability, low installed cost, and ease of on-site construction. 57% of the respondents installed solid wood floors in 1999, followed by 23 % wood I-joists, 9% parallel chord trusses and the balance concrete. When rating floor type against attributes, wood I-joists performed the highest against the top three just mentioned, as well as scoring top marks in design flexibility, technical support, walking comfort and low environmental impact. Out of 15 attributes investigated, wood generally scored higher ratings than concrete except for vibration, sound transmission and fire resistance. It is important to note that solid wood floors scored the lowest of all building materials when it came to the number one attribute, dimensional stability.
Results of this study lead to recommendations for extension and/or further research in the following areas;
1. Dimensional stability of solid wood joists.
2. Vibrations in wood floors.
3. Technical support for using solid wood. .
4. Technical transfer on the environmental performance of wood.
5. Further analysis of floors database for specific inquiries.
6. Creation of products/practices/performance databases for walls and roofs.
A study was performed to determine the feasibility of an outdoor test facility for building envelope materials and components in Vancouver. Test facilities are useful for real-time, real-weather performance assessment of construction materials and assemblies. There are several such facilities in use around the world but none in a climate comparable to that of coastal British Columbia. The feasibility study included a review of existing similar facilities, determination of criteria for a successful Vancouver facility, investigation into research grant opportunities for funding the facility's construction, development of a conceptual design for the facility and its experimental capabilities in order to determine a cost target for fundraising, sampling of a pool of potential paying users of the facility, identification of possible sites and project custodians, and development of a project development plan. The study indicated that the concept for a Vancouver test facility is viable enough to warrant movement into the next phase of project development: handover to a project development team and initiation of fundraising.
We ran two field experiments in summer 2000 to test the feasibility of using two biocontrol agents to protect logs from being stained by wild-type bluestain fungi. Both Cartapip and Gliocladium roseum showed promise to control stain in freshly felled logs for the critical first 12 weeks of storage.
Results show that:
Cartapip applied at the recommended concentration significantly reduced the amount of stain in the Alberta trials.
Cartapip concentration at 1/3 of the recommended concentration resulted in stain that was not significantly different from that in the control logs.
Tim-Bor and the integrated control with G. roseum also significantly reduced stain but less than did Cartapip applied at the recommended level.
In the B.C. trials the stain prevention effect of Cartapip appeared to be stronger in discs that had large sapwood areas (available areas). However, no treatment effects were found to be statistically significant.
We need to repeat the experiment at least once as consistency must be demonstrated before the biocontrol agent can be used industrially. In our next field studies, we will concentrate on Cartapip. Additional studies could look into optimizing the formula and use of product by testing different concentrations of biocontrol agents, adjuvants (spreaders and stickers), and ways of timing application.
In this work, the properties of aspen veneer from two mills (A and B) were compared. The comparisons between the incised veneer and non-incised veneer for mill A were made in terms of veneer thickness, ultrasonic propagation time (UPT), density and MOE. The aspen veneer was further characterized for LVL/plywood products by tailoring veneer grades to the requirements of final veneer products. In addition, MOE-based veneer stress grading and UPT-based veneer stress grading were compared for the aspen veneer. The advantages of MOE-based veneer stress grading over UPT-based veneer stress grading were identified in terms of veneer grade MOE and volume breakdown. The main results are summarized as follows:
1) Aspen veneer properties change from mill to mill. The differences in aspen veneer density and MOE between mill A and B are significant with mill A producing denser and stronger aspen veneer.
2) For aspen veneer in the mill A, the distribution shapes of veneer thickness, UPT, density and MOE between the non-incised and incised veneer are quite similar. Although the differences in veneer thickness, UPT and density between the non-incised veneer and incised veneer are identified as significant, the difference in veneer MOE is not significant due to the effect of both veneer UPT and density. The incised veneer has a slightly higher variation in thickness and is also slightly thicker compared to the non-incised veneer. This could due to the change of lathe settings or the property variation of aspen species as indicated with the veneer density variation.
3) Of the aspen veneer from mill A, using the optimum UPT thresholds, about 27.5 ~ 30.9% can be extracted through veneer stress grading to make 2.0 million psi LVL; about 43.4 ~ 59.9% can be sorted out for 1.8 million psi LVL; and the remaining 12.6 ~ 25.7% can be used for 1.5 million psi LVL or for plywood. It was also found that the incised aspen veneer generates 3.4% less of top stress grade G1 but 16.5% more of stress grade G2 compared to the non-incised aspen veneer if performing the optimum UPT-based stress grading.
4) The MOE-based veneer stress grading not only results in a smaller variation in MOE of each grade, but also higher volume percentages of stress grades G1 and G2 compared to the UPT-based veneer stress grading. This smaller variation in MOE of each stress grade will be very beneficial to the industry and structural applications since higher design stress can be assigned for the wood structural components. Also the higher percentages of stress grades G1 and G2 with the MOE-based veneer stress grading has significant economical implications and should be recognized by the industry.
5) To maximize mill profits, veneer sheets need to be periodically sampled and analyzed using the VGrader software. The optimum grading thresholds for the specific veneer can be established for on-line veneer stress grading based on the current market and requirements of final veneer products, providing a real solution to characterize and make best use of the specific veneer for LVL/plywood products.
Characterizing aspen veneer for LVL/plywood products. Part 2. LVL pressing strategies and strength properties|Manufacturing characteristics and strength properties of aspen LVL using stress graded veneer
In this study, aspen veneer sheets were sampled from a Forintek member mill. Their attributes and properties were measured. Using the optimum stress grading strategy, aspen veneer was segregated into 3 distinct stiffness groups (stress grades G1, G2 and G3) and conditioned to 3 different moisture levels. An experimental design for 3-level four factors comprising veneer moisture content, veneer stress grade, mat pressure and glue spread (or resin level) was adopted. Based on the experimental design, LVL panels with different combinations of four factors were pressed until the target core temperature reached 1050C to achieve full cure followed by a stepwise decompression cycle. The LVL panel final thickness, density, compression ratio and relevant strength properties were measured. After that the effect of aspen veneer moisture, stress grade, mat pressure and glue spread and their relative importance on LVL compression behavior, hot-pressing and strength properties were evaluated using a statistical analysis program. The relationship between LVL panel properties and veneer properties was examined. Finally a method to enhance LVL modulus of elasticity (MOE) to make high stiffness LVL was discussed. From this study, the following results were found:
Aspen veneer is capable of making LVL products meeting 1.8 and 2.0 million psi MOE requirements. Optimum veneer stress grading and proper pressing schedule are two important keys to the manufacture of high-stiffness aspen LVL products. Further, a possibility to make high-grade aspen LVL meeting 2.2 million psi MOE exists by proper veneer densification and optimum veneer stress grading.
The roles of four factors affecting LVL pressing behavior and strength properties are quite different. Glue spread and mat pressure, rather than stress grade and veneer moisture content, are two main factors affecting hot-pressing time taken for the core to reach 1050C. With incised veneer, the moisture from the glue in the glueline affects the rise of core temperature more pronouncedly than the moisture in the veneer, and is more critical to the cure of the glue. High glue spread (44 lbs/1000ft2) not only significantly increases the hot pressing time taken for the core to rise to 1050C, but overall also decreases most LVL strength properties with the pressing schedule used. High mat pressure does not necessarily result in high LVL panel compression due to the high gas pressure that occurs in the core.
Veneer stress grade and veneer moisture are the two predominant factors that mostly affect LVL strength properties. LVL panels assembled with high stress grade result in increases in both flatwise and edgewise MOE and MOR properties rather than shear strength either longitudinal or through-the-thickness. Further, using high stress grade veneer can help make more efficient structural systems in terms of both stiffness-to-weight and bending strength-to-weight ratios compared to using low stress grade veneer. High veneer moisture at 6% impairs all LVL strength properties except edgewise bending MOE.
LVL compression ratio can help link veneer MOE with LVL panel edgewise bending MOE. Overall, every increase of 1% in LVL compression ratio would result in 1% increase in LVL and veneer MOE ratio. With regard to aspen LVL MOE enhancement, using high veneer stress grade gains slightly less than using low veneer stress grade. On average, every increase of 1% in aspen LVL compression ratio results in 0.82%, 1.05% and 1.20% increase in aspen LVL and veneer MOE ratio assembled with stress grades G1, G2 and G3, respectively. In practice, those conversion factors for any specific veneer can be derived based on the correlation between veneer MOE and MOE of target LVL/plywood products made with proper pressing schedules, and be further used to derive requested veneer MOE for each stress grade to perform the optimum veneer stress grading.
Pressing schedules show significant effect on aspen LVL compression behavior and strength properties. Using a pressing schedule with step-wise decompression cycles following the core temperature to rise to 1050C, an excessive compression of LVL in the range of 13.5% to 27.6% is generated which results in high-stiffness LVL with an average MOE of approximate 2.0 million psi for all experiments. Although this pressing schedule has slightly longer pressing time and off-target LVL thickness than current commercial LVL pressing schedules, it helps enhance the strength properties of LVL.
It is recommended that further work should include the effect of different decompression cycles and mat pressure on LVL panel compression ratio and strength properties.