Changes to allow six-storey wood construction under consideration for National Codes

Volume 17, Number 4, December 2012

The Canadian Commission on Building and Fire Codes (CCBFC) is taking a closer look at requirements in the 2010 National Building and Fire Codes of Canada that currently limit the height of wood buildings to no more than four storeys. The initiative was undertaken as a result of code change requests from the Province of British Columbia and the Canadian Wood Council asking that the current height limits for combustible construction be increased. Doing so would move the National Model Construction Codes towards harmonization with various code development initiatives and market access policies being established in jurisdictions across the country. A joint task group encompassing several CCBFC standing committees was established in 2011, led by the Standing Committee on Fire Protection, to review current requirements and make recommendations. Four specific areas were examined: fire protection (building elements); emergency response (fire code requirements); building and plumbing services; and structural and earthquake design.
Proposed changes to increase the height and area limits to six storeys for buildings constructed of combustible materials are under development for the National Model Construction Codes (Photo courtesy of Sukh Johal c/o WoodWORKS!BC)
The task group determined that height and area limits for buildings constructed of combustible materials could safely be increased to six storeys by either introducing new and/or modifying various protective measures. These proposed changes would apply to residential and office-type buildings (Groups C and D occupancies, respectively, in the Codes). They would also include mixed-type occupancies where Group C and D buildings, depending on the top occupancy, may have office, residential, mercantile, assembly, low hazard or storage garage-type occupancies (Group D, C, E, A2, F2, F3 respectively) on the lower levels. To address emergency responder concerns, provisions to allow greater access for firefighting have been proposed, such as requiring that a minimum of 25% of the building perimeter be directly accessible by fire responders. Other requirements would include mandatory sprinklers (conforming to NFPA-13) throughout the building; a fire-resistance rating of not less than one hour for floor and roof assemblies as well as mezzanines; and non-combustible cladding on roofs that are inaccessible to fire hoses. The building could also only be occupied once fire safety features were fully enabled. Further proposed changes dealing with structural and earthquake design, such as changes to seismic force resisting systems, are also being developed. Following acceptance of the proposed changes by the CCBFC, the committees plan to start work on a second phase of this project, which would involve a review of the Codes in their entirety to determine if the concept of combustible/non-combustible construction could be eliminated, augmented, or replaced with performance-based requirements. Research underway at NRC Construction to obtain technical data on the fire safety (see story this issue: NRC fire researchers making strides in mid-rise wood research project), acoustic and building envelope performance of wood-based structural products would be considered in committee discussions at this stage. The policy implications of the proposed changes, including enforcement issues, will be discussed with the provinces and territories during the summer of 2013. The proposed changes are expected to be submitted for public review in fall 2013. Final changes, if approved by the CCBFC, will be incorporated in the 2015 editions of the National Building and Fire Codes of Canada.

For more information

Contact Philip Rizcallah at philip.rizcallah@nrc-cnrc.gc.ca or 613-993-4064.