The common path of egress travel distance is an import concept of egress in the international building code (IBC). Here we will dive deep into exactly what it means and how it affects the code design of a building.
All references uses the 2021 edition of the IBC, but this concept is also found in earlier and later editions.
IBC Section 202 defines the Common Path of Egress Travel as:
That portion of the exit access travel distance measured from the most remote point of each room, area or space to that point where the occupants have separate and distinct access to two exits or exit access doorways.
The italicized words are also defined, so in order to full understand what this means we must also look at those definitions. The IBC defined term of Exit is:
That portion of a means of egress system between the exit access and the exit discharge or public way. Exit components include exterior exit doors at the level of exit discharge, interior exit stairways and ramps, exit passageways, exterior exit stairways and ramps and horizontal exits.
The IBC defined term of Exit Access is:
That portion of a means of egress system that leads from any occupied portion of a building or structure to an exit
The common path of egress travel distance is essentially your max “dead end” distance. Its the maximum distance an occupant must travel before they reach a point where they can go in two different directions to toward two different exits, or until the point that they reach the exit. An “exit” can take on a few forms, a common one being a fire rated stairwell, or a door to the outside.
It is a fairly common code considerations in many building types. Any room, building, or area of a building that has only 1 way out must consider this distance.
A common situation is a double loaded corridor that has a stairwell on each of the building. The common path of egress travel distance goes from the furthest corner of the room until they reach the hallway, where the occupant then has the option to go to two different exit stairwells.
The distance depends on occupancy, occupant load, and whether or not the building is sprinklered. See the chart below:
The above chart is for spaces within a building. There is a different chart, below for if the entire story only has 1 exit.
The below example is a B occupancy room, sprinklered, with an occupancy load of 31 people. Per IBC Table 1006.2.1, we have a maximum Common Path of egress travel distance of 100 ft. It’s actual distance is 79 ft, so it is code compliant. We are also under the maximum allowable number of occupants with 1 exit of 49.
Now, lets hypothesize the building is non sprinklered. Then, the maximum common path of egress travel distance is now 75 ft. Now, you would exceed the common path of egress travel distance. The simplest solution would be to add a second door out of the room, or make the room smaller. Now, you have virtually 0 ft of common path of exit travel distance as from all points in the room you have two distinct paths to two exits.
Note that if there is fixed furniture, this should be taken into account when layout out the egress paths to go around this.
Below is another slightly more complex scenario. It features a front manufacturing area and a back storage area. The back storage area must consider the maximum common path of egress travel distance of 75 ft. We must travel 60 ft until we reach the front area where we now have two distinct paths to two exits. So, this example complies. The S occupancy rear area also must be under 29 occupants, which it is.
Article by: Matthew Taylor-Rennert
