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.