In certain applications, fire doors are required to minimize the transmission of heat from one side of the door to the other, as in the stairwell of a high-rise building or in horizontal exits. These doors are fire-resistance rated, as opposed to fire-protection rated. If the door can limit the transmission of heat for a period of time, people can safely pass below the floor of fire origin in a burning building. These doors are built with a core that is specifically designed to restrict the transmission of heat and are referred to as temperature rise doors.
In addition to the hourly rating, the fire door label will also state the temperature rise rating of the door. Temperature rise ratings are 250°F (139°C), 450°F (250°C), and 650°F(361°C), and the ratings indicate the maximum rise in temperature above ambient temperature measured on the unexposed surface (non-fire side) of the door during the first 30 minutes of the standard fire test. In some applications the International Building Code (IBC) requires a 450° F (250°C) temperature rise rating for doors, interior exit stairs and ramps, and exit passageways. The 250°F (139°C) temperature rise designation is the most stringent rating of the three, since itrequires the most limited rise in temperature. A 250°F (139°C) temperature rise door meets the requirements of specifications calling for a 450°F (250°C) or 650°F (361°C) temperature rise rating.
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