Fire testing of doors and hardware and the resulting labeling authorities granted, is a complex subject that is better understood when basic rules and guidelines are applied.
The fire rating classification of the wall into which the door is installed dictates the required
fire rating of the door. The location of the wall in the building and prevailing building code establish
the wall’s fire rating. The associated door ratings are shown in table 1 below.
2.1 Hourly ratings
Steel fire doors are “rated” by time (in minutes or hours) that a door can withstand exposure
to fire test conditions. Hourly ratings include 1-1/2-hours, 1-hour, 3/4-hour, and 1/3-hour,
with the maximum rating required of any swinging type fire door being three hours.
2.2 Three-hour (180 minute) doors A door with a three-hour fire protection rating
is usually found in walls that separate buildings or that divide a large building into
smaller fire areas. The wall rating is four hours.
2.3 1-1/2-hour (90 minute) doors
Doors rated for 1-1/2 hours are found in 2-hour rated walls. These doors are commonly located
in stairwells, or other enclosures of vertical communication through a building. They
also occur in boiler rooms and in exterior walls that have potential for severe fire exposure
from the outside the building.