The means of egress is critical to the safety of occupants in every occupied structure. When a fire situation occurs an integral part of the safety of the occupants is the proper function of the egress systems. There are several principals that means of egress is based on:
- Occupants will have choices on how to evacuate.
- The system will accommodate the number of occupants and provide some separation from the fire.
- The path is clear, illuminated and marked. This includes the simple fact the all aspects of the egress system are under the control of the occupant (excluding prisons of course).
Egress is not the only life safety system. A main idea behind egress is that life safety is typically related to time. The faster we can report a fire and notify the occupants, the likelihood for them to escape without injury is great (install smoke alarms or notification fire alarm system). If we can slow the fire growth down or extinguish the fire a panic situation may not occur (installing sprinklers or other approved fire suppression system).
What are the basics of an egress system:
Egress has three main parts; the exit access, the exit, and the exit discharge. The 2006 editions of the International Building and Fire Code, provide definitions for these terms in section 1002 and NFPA Life Safety Code 2007 edition, provides definitions in chapter 3 (Exit 3.3.75, Exit Access 3.3.76. Exit Discharge 3.3.77). They are similar defined as:
- Exit Access, That portion of a means of egress that leads to an exit.
- Exit, That portion of a means of egress that is separated from all other spaces of a building or structure by construction or equipment as required to provide a protected way of travel to the exit discharge.
- Exit Discharge, That portion of a means of egress between the termination of an exit and a public way.
If I am in an occupied building and in my office, that area is called the exit access. The path of travel that I take to the stairway is considered the exit access as well. If I step into a rated stairwell I am now in the exit.
If the stairway is not rated, the space is part of the exit access. If I work on the first floor the door that leads to the outside is considered the exit. Once I leave the door and walk to my car, I am in the exit discharge.
Key Ingredients of the Means of Egress
- The means of egress shall have a ceiling height of not less the 7 feet 6 inches, except those approved protruding objects
- Walking surfaces of the means of egress shall have a slip-resistant surface and be securely attached
- Elevators, escalators and moving walks shall not be used as a component of a required means of egress from any other part of the building (except if part of an accessible means of egress).
- Any device or alarm installed to restrict the improper use of a means of egress shall be designed and installed so that it cannot, even in case of failure, impede or prevent emergency use of such means of egress, unless otherwise approved by the appropriate code.
- Means of egress shall be continuously maintained free of all obstructions or impediments to full instant use in the case of fire or other emergency.
- Doors in the means of egress shall not require special knowledge or locking arrangements.
There are many issues which affect the means of egress and are a key component in safety of occupants. Stories such as the station night club fire, the E-2 disaster, and the Dance King Nightclub (China) make us all realize that the egress system must be protected at ensure that all occupants can leave a structure. Understanding the fundamentals of egress is only the start as future parts of this topic will be look at which include allowed egress length, interior finish requirements, and delayed egress locking.