This report provides the methods and summarizes the results of Forintek research to characterize the properties of British Columbia lumber containing beetle-transmitted bluestain.
In 2003 Forintek Canada Corp. collected approximately 30 pieces of bluestained lodgepole pine lumber cut from beetle-attacked trees, and an equivalent amount of non-bluestained lumber from each of 14 different sawmills in the B.C. Interior. The geographic range of beetle attack was represented in the sampling plan. The wood was delivered to the Forintek Vancouver laboratory for conditioning and processing into test specimens. The specimens were allocated, in equal proportion from each mill, between tests of mechanical, dimensional stability/permeability, gluing, and finishing properties.
This research represents the first comprehensive study and compilation of the properties of beetle-transmitted bluestained wood. Overall, the research indicates that this wood can be used, without compromising performance, for structural, furniture, and preservative-treated end uses.
A factsheet summarizing the findings produced for customers of bluestained wood is included in the appendix to this report.
Many sawmills in Canada are focused on the production of dimension lumber and use productivity levels as a measure of their success. Such mills are often unwilling to produce directly for remanufacturers or specialty product manufacturers because they believe that producing small volumes of off-sized lumber will negatively impact productivity.
This report describes the use of sawmill simulation tools to evaluate the impact on sawmill productivity of augmenting a product mix comprised of dimension lumber only with specialty sized lumber targeted toward producers of value-added wood products. The simulation tools utilised in this project were able to estimate productivity changes resulting from processing varying percentages of the log diet to higher valued, rough green products. When a relatively low percentage of logs were deemed suitable for non-standard sizes, and when the grade yields were assumed to be high, the impact on productivity was, as expected, minimal. However, productivity was observed to decrease with increasing percentages of logs from which higher valued products could be targeted, and also with decreasing grade yields.
Due to the inherent limitations of the present generation of sawmill simulation tools, namely their inability to consider defect other than wane, a number of simplifying assumptions were made regarding the proportion of logs suitable for higher valued products as well as grade yields from said logs. The results of this study must be viewed in the context of these assumptions.
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.
When constructing timber structures, it is important that structural members such as beams, columns, and trusses be designed to carry the specified loads, because no chain is stronger than its weakest link. It is equally important that the connections joining these members be carefully designed. A connection must be able to transfer the load and its effects from one member to the other within acceptable deformation limits. Adequate connection behaviour is especially important for structures built in seismically-active regions where inappropriate connection design can lead to structural collapse during a major earthquake. The introduction of various wood products to the market has increased the opportunities for wood use in various structural applications, thereby increasing the importance of connections as structural components.
Finished wood used outdoors can become unserviceable within a few years if not effectively protected against ultra-violet (UV) light and moisture deterioration. For exposed outdoor wood the finish is especially important, as it is the main defence against weathering. At the same time, extended service life, low-cost maintenance and, where possible, preserving the natural appearance of wood is increasingly demanded by customers.
When properly finished, exterior wood can last a long time. For example, latex paints have performed well for 10 years or longer. By comparison, improperly finished wood can fail due to flaking, cracking, erosion and discolouration after only one year of exposure. Finish lifespan depends on several principal factors including service conditions, wood substrate properties and finish type. Understanding these factors and how they link together is needed to maximize the performance of any finished wood product for exterior applications.
Western Canadian hardwood lumber is not difficult to dry. However, each of these commonly available species has certain characteristics that will cause problems in the drying process if not dealt with correctly. Significant business failures have resulted when producers have ignored these hardwood-specific characteristics and applied generic softwood drying schedules. As a rule, typical softwood drying practices will not produce good results for hardwood products.
While the industry is placing greater emphasis on producing higher-value secondary wood products, there is a concurrent need to understand species-specific characteristics as the wood goes through various manufacturing processes.
Forintek assists secondary wood processors in the design and manufacture of higher-value products, and helps promote Canadian species in domestic and export markets. To reach the high quality standards required by today’s end-user of value-added wood products, Forintek is assisting manufacturers choose the appropriate species and process technology for their products.
Quality gluing is critical to the manufacture of quality value-added products. Poor gluing practices can cause your company to lose money, customers, morale and reputation—all of which are difficult to recover.
To ensure satisfactory performance of edge-glued, laminated or finger-jointed wood products, manufacturers need to pay close attention to a number of processes and variables that affect the quality of glue joints. Some of the variables include the product and its end-use, the type of adhesive, the moisture content and storage of wood to be glued, as well as wood properties. Processing variables range from preparation of the surfaces to be glued, and mixing of the adhesive, to glue application variables and quality control procedures. The purpose of this Profile is to provide a summary of the key factors that affect the production of good glue joints.
Even though fire-resistance (FR) ratings for generic assemblies traditionally used in construction of Canadian housing and small buildings had been published in every edition of the National Building Code of Canada (NBCC) since 1950, and in the later years, sound-transmission-class (STC) ratings were also listed for each assembly, in 1992 the Canadian Commission for Building and Fire Codes (CCBFC) decided to delete from the 1995 edition of the NBCC, all STC and FR ratings that could not be supported by contemporary data.
Architects, fire-protection engineers and building officials make extensive use of the STC and FR ratings in the NBCC when designing and approving housing and small buildings in Canada. The STC ratings are also used extensively in the design of larger engineered structures. Wood-frame assemblies more than any other, are designed and constructed in accordance with the STC and FR ratings listed in the NBCC. Therefore, it was crucial for the wood industry to generate the necessary data to retain STC and FR ratings for wood-frame assemblies in the building code.
In 1992 a partnership of affected industries and governmental organisations was created, and the National Research Council Canada (NRC), in collaboration with those partners, commenced a research program to quantify STC and FR ratings for generic building assemblies protected by gypsum board. Forintek Canada Corp., in conjunction with the Canadian Wood Council (CWC) and a number of North American manufacturers of engineered wood products, participated in that program on behalf of Canada’s wood products industry.
At the same time that NRC was carrying out the collaborative program to quantify STC and FR ratings for generic building assemblies, they, in collaboration with many of those same partners including Forintek Canada Corp., carried out a separate program to identify construction designs which minimise flanking paths for noise at the connections between floor assemblies and partywalls separating adjoining units in wood-frame apartment buildings.
All empirical studies for this project were completed by March 31, 2004. Writing, reviewing and publishing of the final reports by the researchers at NRC will require an additional four to six months to complete. Nevertheless, even though some of the deliverables including the final NRC reports for the collaborative Floors-II and Phase-III Flanking projects and the best-practice design guide for design of wood-frame structures with adequate noise insulation will not be submitted to Forintek until sometime later in the year, and there are additional revisions to Table A-126.96.36.199.B. Fire and Sound Resistance of Floors, Ceilings and Roofs in the NBCC to be formulated and shepherded through the code approval process, this project ended on March 31, 2004. Forintek’s participation in reviewing of NRC’s final reports and in any subsequent technology transfer activities will be carried out under new, short-term projects. Forintek will continue to write papers for presentation at conferences, seminars and workshops and for publication in journals and other written media in order to get the message out about this project and the acoustical and fire performances of wood-frame construction. However, those activities too will be conducted under new projects.
If this research had not been carried out, only twelve designs for wood-frame walls would have been presented in Table A-188.8.131.52.A. Fire and Sound Resistance of Walls of the NBCC and there would have been only eighteen wood-frame floor ceiling assemblies in Table A-184.108.40.206.B. Fire and Sound Resistance of Floors, Ceilings and Roofs. Solely because of this research project, there are now 10½ pages of designs for wood-frame walls in Table A-220.127.116.11.A., 36 pages of designs for wood-frame floor-ceiling assemblies in Table A-18.104.22.168.B., and there will be at least 20 more pages of such information added to Table A-22.214.171.124.B. latter this year.
The results of this research project confirmed the appropriateness of NBCC provisions regarding firestopping in double-stud partywalls separating living units in multi-storey multifamily dwellings (Article 126.96.36.199. Fire Stopping in Wall Assemblies), and identified methods to minimize flanking of noises across those partywalls.
The results of this research project have permitted hotels chains, including Marriott Hotels, to continue to construct high-quality wood-frame hotels by providing them with solutions to noise transmission problems associated with such structures.
The list of published reports and presentations by Forintek’s fire scientists which have resulted from this research project is more than two pages in length. The list of NRC Client Reports and Internal Reports describing the results of the various sound and fire tests is more than three pages in length. In addition, NRC’s fire scientists and acousticians have published many other reports and have given numerous presentations based upon the results of this research. And, there will be many more by both Forintek and NRC researchers.
Through their leadership roles on standards writing committees, and backed up with information gained through their participation in this research program, wood-industry fire scientists have been able to make the key arguments that resulted in major changes to critical fire resistance test standards: changes that had been stalled for lack of such supporting data for more than a decade.
NRC instrumented every assembly for fire-resistance testing with many more thermocouples and linear deflection transducers than is specified in the test standards. Also, the physical characteristics of all materials used in construction of each assembly were fully documented. The resulting data were invaluable for validation of computer fire models developed by Forintek and NRC researchers, including Forintek’s WALL2D model for predicting the thermal response of walls to standard fire exposures, and the model to predict the fire resistance of wood stud walls developed collaboratively by Forintek and NRC.
One of the most important accomplishments of this research program was that it brought together various aspects of building science (fire resistance, structural engineering, and acoustical performance) under one umbrella research program. Previously, researchers would investigate one aspect of building performance at a time, and all too frequently, the solutions that they derived to mitigate one problem, would unknowingly exacerbate others.
Also, this research program brought various material interests together to resolve building code issues. For perhaps the first time, representatives for the manufacturers of gypsum board, various insulation products, concrete, light-structural steel and wood products worked together towards a common goal. Modern buildings are not constructed with a single building material. It made economical sense for all the material interests to work together in assessing the performance of buildings constructed with various combinations of their products. It also permitted each to learn about the design and performance problems faced by the other materials interests and of their design solutions for those problems. This has been of critical importance for the wood industry as it tries to protect its traditional markets from competition from steel and concrete products.