Canada's National Code System
On behalf of the Canadian Commission on Building and Fire Codes (CCBFC) the National Research Council (NRC) Canadian Codes Center publishes national model codes documents that set out minimum requirements relating to their scope and objectives. These include the National Building Code, the National Fire Code, the National Plumbing Code and other documents. The Canadian Standards Association (CSA) publishes other model codes that address electrical, gas and elevator systems.
Requirements on the specification of structural wood products and wood building systems is set forth in the National Building Code which is concerned with health, safety, accessibility and the protection of buildings from fire or structural damage. The Code applies mainly to new construction, but also aspects of demolition, relocation, renovation and change of building use. The current NBCC was published in 2010, and is usually updated on a five-year cycle. The next update is expected in 2015.
Objective Based Format
The current edition of the National Building Code of Canada is published in an objective based format intended to allow more flexibility when evaluating non-traditional solutions. The Objective- based Code currently in use provides additional information that helps proponents and regulators determine what minimum performance must be achieved to facilitate evaluation of new alternatives. Although the Code helps users understand the intent of the requirements, it is understood that proponents and regulators will still have a challenge in terms of demonstrating compliance. In any case, objective based codes are expected to foster a spirit of innovation and create new opportunities for Canadian manufacturers.
Model codes have no force in law until they are adopted by a government authority having jurisdiction. In Canada that responsibility resides within the provinces, territories and in some cases, municipalities. Most regions choose to adopt the NBCC, or adapt their own version derived from the NBCC to suit regional needs. Some links to provinces that have adopted their own version of the Building Code are provided below:
Parts of the Building Code
In Canada structural wood products are used prescriptively or by design depending on the application and occupancy. Design professionals are generally required for structures that exceed three storeys or are greater than 600 square meters, or if occupancies not covered by Part 9 of the Code.
Buildings Requiring Design Professionals
Buildings that fall outside of prescriptive boundaries or intended for major occupancy or post disaster situations must be designed in accordance with Part 4 of the Code by design professionals. These structures are designed using loads and engineering mechanics calculations specified in Part 4. Structural resistance to Part 4 loads is specified in the material standard for engineering design, which for wood is CSA Standard O86 " Engineering Design in Wood". For more information also see the Structural page
For information on how fire safety is addressed in the NBCC see the fire section.
Buildings Requiring Prescriptive Design
Housing and small buildings can be built without a full structural design using prescriptive requirements found in Part 9 of the Code. Some Part 9 requirements are based on calculations, others are based on construction practices that have a proven performance history. Generally prescriptive use is allowed if the following conditions are met:
- 3 stories or less
- 600 square meters or less
- uses repetitive wood members spaced within 600 mm
- spans are less than 12.2 meter
- floor live loads don't exceed 2.4 kPa
- residential, office, mercantile or medium-to low-hazard industrial occupancy
The rationale for not basing all Part 9 requirements on calculations is that there has been long experience with small wood-frame buildings in Canada, and many of the non-structural elements actually contribute to the strength of the structure. Quantifying this contribution cannot be done adequately using typical design assumptions that include two dimensional load paths and single member engineering mechanics. In these cases the qualification of houses and small buildings is based on alternative criteria of a prescriptive nature. These prescriptive criteria are based on an extensive performance history of wood housing and small buildings that meet current day code requirements.
Code Referenced Publications
The Canadian Wood Council has developed the Engineering Guide for Wood Frame Construction. The Guide gives background information on the wood frame requirements of Part 9, provides guidance in defining situations where engineering design is required to supplement the prescriptive requirements, outlines design procedures, and provides design aids.
Links to additional referenced publications are provided below:
Codes in other Countries
Building codes in the United States also address minimum requirements of health and safety. Regulatory requirements are adopted both on a state and municipal level. Information on American Building Codes can be found at:
Additional US building code information relating to wood products can be found here.
The U.S. model codes also reference American Forest and Paper Association's wood design standards such as the ANSI Allowable Stress Design (ASD) Manual for Engineered Wood Construction - 2001 Edition, and the American Society of Civil Engineer's Load and Resistance Factor Design Manual for Engineered Wood Construction.