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 LabelRatingRatingMax. Glass Area
A3 HR180 MIN100 square inches per leaf
B1 1/2 HR90 MIN100 square inches per leaf
C3/4 HR45 MIN1296 square inches per lite
D1 1/2 HR90 MINRefer to local codes
E3/4 HR45 MINRefer to local codes
1/3 HR20 MIN1296 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 AssemblyWall RatingMinimum Door Rating
Fire Wall / Fire Barrier4 HR180 MIN
Fire Wall / Fire Barrier3 HR180 MIN
Fire Wall / Fire Barrier2 HR90 MIN
Fire Wall / Fire Barrier1 1/2 HR90 MIN
Fire Barrier Having a 1 HR FRR*1 HR60 MIN
Other Fire Barriers1 HR45 MIN
Fire Partitions (Corridor Walls)1 HR20 MIN
Fire Partitions (Corridor Walls)30 MIN20 MIN
Other Fire Partitions (Non-Corridor Walls)1 HR45 MIN
Other Fire Partitions (Non-Corridor Walls)30 MIN20 MIN
Exterior Walls3 HR90 MIN
Exterior Walls2 HR90 MIN
Exterior Walls1 HR45 MIN
Smoke Barriers1 HR20 MIN
* Enclosures for shafts, exit access stairs, exit access ramps, interior exit stairways and ramps, exit passageway walls.

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.

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