Fire separations and fire-resistance ratings are often required together but they are not interchangeable terms, nor are they necessarily mutually inclusive.
The National Building Code of Canada (NBC)1 provides the following definitions:
A fire separation is defined as “a construction assembly that acts as a barrier against the spread of fire.” A fire-resistance rating is defined as “the time in minutes or hours that a material or assembly of materials will withstand the passage of flame and the transmission of heat when exposed to fire under specified conditions of test and performance criteria, or as determined by extension or interpretation of information derived therefrom as prescribed in [the NBC].”
In many buildings, the structural members such as beams and columns, and structural or non-structural assemblies such as walls and floors, are required to exhibit some degree of resistance to fire in order to prevent the spread of fire and smoke, and/or to minimize the risk of collapse of the building in the event of a fire. However, fire separations are assemblies that may or may not be required to have a specific fire-resistance rating, while structural members such as beams and columns that require a fire resistance rating to maintain the structural stability of a building in the event of a fire are not fire separations because they do not “act as a barrier against the spread of fire.”
Requirements for fire separations and fire-resistance ratings are just one aspect of the fire-safe design approach used by the Code to reduce risk to building occupants of injury, as well as to reduce risk of property loss. Together, they are key elements to the strategy of controlling fire spread called “compartmentation.”
