The Basics of Swinging-Type Egress Door Operation
Door assemblies serve multiple purposes that relate to the comfort and safety of building occupants. They provide protection from weather, reduction of noises from adjoining areas, prevent trespassing by unauthorized persons and slow or stop the spread of fire and smoke. While seemingly so commonplace, door assemblies can become an impediment to occupants if they are locked or inoperable.
Doors within a means of egress include those non-fire-rated, fire-rated and smoke-resisting door assemblies. None of these will perform properly if left open during a fire. There are many examples of fires where fatalities resulted because of doors that were left open. There are also examples of fires where lives were saved because a door leaf was closed. Unfortunately, there are those fires in which door openings needed for escape were blocked or locked, resulting in devastating losses. Just this week, an eight-alarm fire in Queens, New York City, displaced 240 residents and injured people, including 16 firefighters. The fire was reported to start in a unit on the top floor. An occupant fleeing the building left the door open to the apartment unit, causing the fire to spread into the hallway and to other areas of the building.
To help ensure safe door operation during an emergency, considerations must be given to the type of door, width of opening and door leaves, door swing direction, encroachment, the force required to operate the door, and the locking and latching devices. Here we will focus on those fundamental operational features only for side-hinged or pivoted-swinging type egress doors as these include the majority of doors an occupant will likely face while egressing a building. Other door types may be permitted in lieu of swinging doors but these will be addressed separately.
Minimum Width
Door openings must be of sufficient width to ensure that enough people can pass through the openings quickly and safely during egress. Too narrow of an opening, or not enough total available capacity can create bottlenecks, and obstruct the flow of occupants leaving as they move towards a safer area.
Minimum door width is prescribed as (1) clear width, (2) egress capacity width, or (3) leaf width and when a specific minimum width is required by the Code, the specific width will be refenced. Specifying a door leaf width (the width of the door leaf, not the opening) is the least common case, and more often a minimum clear width or egress capacity width is mandated. Door width measurements might be used in calculating egress capacity or in determining if a minimum door width requirement is met. Depending on the purpose for which the door width measurement is used, the allowable encroachments on opening width vary.
Measuring egress capacity width for a new door leaf that opens 90 degrees
(Credit: NFPA 101 Handbook, 2021 edition)
Measuring egress capacity width for a new door leaf that opens 90 degrees
(Credit: NFPA 101 Handbook, 2021 edition)
Clear width of a door opening is used for meeting minimum door-opening requirements, not for determining egress capacity. In some cases this minimum clear width value is based on the need for occupants traveling in a wheelchair to be able to move the wheelchair through the door opening. The egress capacity width, used to determine how many occupants can be credited with passing through the opening safely, will be less than the actual door leaf width because deductions in width are made for certain encroachments that extends into the door opening.
Note: This describes the types of various door width measurements, but users should reference Section 7.2.1.2 of NFPA 101 for further details about how to obtain these measurements in both new and existing conditions.
Door Swing Direction
Door leaves are required to swing in the direction of egress travel only if any one of the following three conditions exist:
- The door serves a room or area with an occupant load of 50 or more,
- The door assembly is used in an exit enclosure,
- The door opening services a high-hazard contents area.
These three conditions address situations where it is undesirable for an occupant to take time to pull the door open in the direction they are moving from. This could be due to the higher number of occupants, or where conditions exist that could require instant and immediate access to the path of egress travel due to extreme fire or explosion risk.
Ideally, all door leaves in a means of egress would swing in the direction of egress travel. However, because of operational concerns, there are cases where door leaf swing in the direction of egress travel is not desirable. For example, a classroom door leaf that swings into a corridor serving as an exit access for several classrooms might open against another door leaf or against the flow of people and possibly restrict the width available as corridor exit access. The Code recognizes this danger and permits the classroom/corridor door leaf from a room with an occupant load of fewer than 50 persons to swing against the direction of egress travel.
Encroachment
To minimize the risk of a door restricting the width available of other egress components, the Code establishes maximum encroachment allowances. During its swing, any door leaf in a means of egress is required to leave not less than one-half of the required width of where it is opening. When the door is fully open, is cannot project more than 7 in (180 mm) into the required width of the aisle, corridor, passage or landing unless the door is equipped with a proper self-closing device and swinging in the direction of egress travel. These two conditions help to ensure that the door leaf does not become an obstruction in the egress path onto which it opens which could reduce capacity and delay egress travel. There are no encroachment limitations for a door opening that provides access to a stair in an existing building.
Door leaves capable of swinging a full 180 degrees have a greater utility than door leaves capable of swinging only 90 degrees. The 180-degree-swinging door leaf can be fully opened into a corridor without significant intrusion on corridor width. The 90-degree-swinging door leaf, however, might have to open into an unusually wide corridor, be set into an alcove, or otherwise be recessed so as not to exceed the maximum encroachment.
Door leaf swing into a corridor
(Credit: NFPA 101 Handbook, 2021 edition)
Door leaf encroachment on landing in new building.
(Credit: NFPA 101 Handbook, 2021 edition)
Unlatching Force
Several movements are necessary to move a door leaf from its closed to its fully open position. The force needed to unlatch the door assembly cannot exceed 15 lbf (67 N) for hardware that may push pull or slide and 28 in.-lbf for hardware that requires rotation. Additional limits are placed on the force to start the door leaf in motion and on the force necessary to move the door leaf to its required open position. Consideration must be made for persons with severe mobility impairment, such as someone using a wheelchair, who might find it difficult or impossible to exert excessive force to unlatch the door and put it in motion. Additional scenarios may render others incapable of exerting larger forces, so values as high as 50 lbf which were recognized in earlier editions of the Life Safety Code, are now only acceptable for existing installations.
Locking and Latching
Doors within an occupant’s means of egress cannot be locked beyond their control but must also be designed to accommodate building’s and occupant needs for security. If done incorrectly, door locking and latching can become a severe impediment to free and safe egress. The details and permissions for door locking and door latching are extensive, and must not be overlooked. We will address this subject in its entirety in a future blog (stay tuned!)
In conclusion, leaving a building or moving within a building to a point of safety in the event of an emergency is almost guaranteed to include using doors to get there. Proper door operation is critical to occupants being afforded a safe and efficient means of egress. Adequate door opening width, correct door swing direction, minimal encroachment, and appropriate opening and unlatching forces, combined, will work together to provide occupants with reliable and safe door operation.
(Note: Additional details and requirements related to door operation can be found in NFPA 101, Life Safety Code, Section 7.2.1.)
