Even though sound-transmission-class (STC) and 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, 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.
No single organisation in Canada could afford to bear the costs associated with a testing program to determine STC and FR ratings for all assemblies commonly used in Canadian housing and small buildings. Therefore, 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, is participating in that program on behalf of Canada’s wood products industry. This report describes progress achieved in that research program between April 1, 2002 and March 31, 2003.
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.
Revisions to Table A-9.10.3.1.B. Fire and Sound Resistance of Floors, Ceilings and Roofs in the NBCC and the accompanying Appendix Note A-9.10.3.1 were published on the CCBFC website. The revisions include FR ratings for 80 wood-frame floor/ceiling assemblies, and STC and impact-insulation-class (IIC) ratings for 348 wood-frame floor/ceiling assemblies. The table includes assemblies constructed with timber joists, wood I-joists and metal-plate-connected parallel-chord wood trusses. Prior to the revisions, Table A-9.10.3.1.B provided ratings for just eighteen wood-frame floor/ceiling assemblies.
A number of technology-transfer activities were carried out between April 1, 2002 and March 31, 2003:
q A paper by L. Richardson entitled “Thoughts and Observations on Fire-endurance Tests of Wood-frame Assemblies Protected by Gypsum Board” was published in Fire and Mater.
q L. Richardson gave a presentation entitled “Fire Safety and Acoustical Design of Wood-frame Buildings” at the Canadian Wood Council Wood Solutions Fair in Ottawa.
q L. Richardson gave a presentation entitled “Fire Safety and Acoustical Design of Wood-frame Buildings” at the annual meeting of the Building Officials Association of British Columbia in Burnaby.
q L. Richardson gave a presentation entitled “Update: Fire and Acoustics Research, Codes and Standards Issues” at the Structural Board Association’s World OSB Symposium in Chicago.
q L. Richardson gave a presentation entitled “Composite Structural Wood Products” to staff at the NRC in Ottawa.
q Forintek published a twelve-page full-colour booklet entitled “Wood-frame Construction, Fire Resistance and Sound Transmission”.
q Forintek updated and republished a four-page full-colour booklet entitled “Fire Safety - A Wood-frame Building Performance Fact Sheet”.
NRC researchers presented a series of one-day Building Science Insight Seminars entitled “Sound Isolation and Fire Containment Details that Work” in cities across Canada.
In fulfillment of a collaborative research agreement with Forintek, National Research Council Canada Final Report A1080.4 entitled “Flanking Transmission in Multi-Family Dwellings: Phase II” was submitted to Forintek. The report describes the results of research on the flanking of noise in wood-framed construction due to continuous structural elements that pass under a partition wall between two horizontally separated dwellings in multi-storey apartment buildings.
A senior NRC acoustician utilising acoustical data generated through this research project and regression-analysis approaches developed “relatively simple” mathematical expressions that predict sound transmission (STC and IIC) through floor/ceiling assemblies.
L. Richardson attended meetings of the American Wood Council (AWC) Subcommittee on Fire Performance of Wood, and the AWC Technical Committee. Many issues related to the fire-resistance of wood-frame buildings were discussed: two of the more important being the fire resistance of floor assemblies without fire protective ceiling membranes attached to the bottom of the floor joists and the risk to firefighters during fires in “lightweight” wood-frame buildings.
This research project will be continued in 2003/2004. The ultimate completion date for the project is March 31, 2004 (unchanged).