Fire rated doors are used in buildings to prevent the passage of fire and smoke between two compartments or areas. They are used as a passive means of protecting people and property from fires.
Doors and frames are given a fire-resistance rating after extensive testing by the Underwriters Laboratory in the United States, or another testing agency in other countries. Once tested, the door and frame receive a label that describes the amount of time the component is expected to provide protection when exposed to fire. When combined, all of the components of the door form an assembly that protects the opening. For this reason, all components of the door must include a rating label, including the door panel, the door frame, locksets, gaskets, hinges, and door protection plates.
A permanent label is attached to the door panel and the door frame, usually on the hinge side of both. Most other components have a UL symbol formed or stamped into the material to identify that they meet the UL requirements.
Local codes should be reviewed, but in general, rated doors must be self-closing and must have a positive latch. There are also limits to the size of glazing in the door, the width of gaps between door panels, the height of the door under-cut, and the size of air transfer grilles.
Chart of Door Ratings and UL Labels
|UL Label||Rating||Rating||Max. Glass Area|
|A||3 HR||180 MIN||100 square inches per leaf|
|B||1 1/2 HR||90 MIN||100 square inches per leaf|
|C||3/4 HR||45 MIN||1296 square inches per lite|
|D||1 1/2 HR||90 MIN||Refer to local codes|
|E||3/4 HR||45 MIN||Refer to local codes|
|1/3 HR||20 MIN||1296 square inches per lite|
UL Labels D and E are for exterior doors that are subject to fire hazards from the outside of the door.
Required Door Ratings Based on Partition Rating
The required door rating is based on the rating of the partition or barrier that the door is in. The table below provides an overview, but the building code should be referenced due to the complexity involved in determining the rating of the partition and the type of opening allowed. Table 716.5 in the International Building Code provides a detailed list of requirements. Local codes may vary.
|Type of Wall Assembly||Wall Rating||Minimum Door Rating|
|Fire Wall / Fire Barrier||4 HR||180 MIN|
|Fire Wall / Fire Barrier||3 HR||180 MIN|
|Fire Wall / Fire Barrier||2 HR||90 MIN|
|Fire Wall / Fire Barrier||1 1/2 HR||90 MIN|
|Fire Barrier Having a 1 HR FRR*||1 HR||60 MIN|
|Other Fire Barriers||1 HR||45 MIN|
|Fire Partitions (Corridor Walls)||1 HR||20 MIN|
|Fire Partitions (Corridor Walls)||30 MIN||20 MIN|
|Other Fire Partitions (Non-Corridor Walls)||1 HR||45 MIN|
|Other Fire Partitions (Non-Corridor Walls)||30 MIN||20 MIN|
|Exterior Walls||3 HR||90 MIN|
|Exterior Walls||2 HR||90 MIN|
|Exterior Walls||1 HR||45 MIN|
|Smoke Barriers||1 HR||20 MIN|
Fire Rated Door Modifications
Field modifications of a fire rated door require specific knowledge of the codes and should be performed by a person certified to work on rated openings. NFPA 80 provides specific guidance on what can and cannot be done to a rated door. It is important to confirm that all new components have a label that matches the rating of the existing door and frame.
Fire Rated Door Annual Inspection
In the United States, NFPA 80 requires that fire rated doors be inspected each year to confirm that the door is in good condition and that all of the required components work as required. The building owner is responsible for having the inspections done by certified inspector and for maintaining proper records of the inspections.
Refer to the codes applicable to your specific jurisdiction for label or rating requirements.