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Means of Egress: The Lifeline of a Building – Part 1
Protection of life is the primary purpose of building codes. Paramount to this purpose is the path of egress travel, especially as it relates to mass exit during an emergency. Unfortunately, many people have needlessly died when they’ve been unable to escape a burning building. In response to these tragic fires, building codes were created to put minimum life safety requirements into place. One of these requirements is means of egress and it is the lifeline of a building.
Means of Egress
Every building code addresses means of egress. According to the International Building Code, this is defined as “a continuous and unobstructed path of vertical and horizontal egress travel from any occupied portion of a building or structure to a public way.” That sounds complicated. But it’s really not. Basically, a means of egress is an exiting system. Its main objective is to get people out of a building safely and quickly during an emergency event. When designing a means of egress, a life safety engineer needs to consider how a building’s design features will impact the movement of people. In general, building design should aid egress, not impede it.
Each building provides unique challenges, and life safety engineers should do more than simply design to meet code. They should analyze the facility to maximize the safety and protection of its occupants. To do this, it’s essential to understand the three distinct components to means of egress:
1) Exit Access
3) Exit Discharge
1) Exit Access
The exit access always leads to an exit. It starts from any point in a building and ends at an exit. In other words, exit access is the part of the building occupied by people. In an emergency, these are the spaces in need of evacuation. For a typical office building, the exit access is the path from a person’s desk to an exit. The exit access includes any intervening spaces, such as aisles or corridors. It provides the most flexibility as far as occupant movement. However, it also provides the least amount of protection.
An exit is separated from all other spaces in a building. It provides protected egress between the exit access and the exit discharge. Exits include both interior and exterior exit stairways and ramps, exit passageways, and horizontal exits. Exits cannot be used for any purpose other than exiting. These spaces cannot include furniture, storage, or work space. Doing so might block the exit. Once a person enters an exit, he or she is considered safe from the effects of fire.
3) Exit Discharge
Exit discharge is the final element of the means of egress. This is the portion of egress travel between the end of an exit and the start of a public way. Simply put, it’s the path of travel away from a building. Ideally, exits should discharge directly to the outside of the building. Since the exit discharge includes everything between the outside of a building and the public way, all these elements are subject to code requirements.
Proper Design Saves Lives
Looking at empirical data, human behavior research, and historical precedent, life safety experts have valuable insight to design safer buildings. We have seen building codes continue to evolve over time. Undoubtedly, a well-engineered means of egress is one of the most valuable lifelines during an emergency.
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