Choice of two exits...but one is outside POT

[admiralArchArch]

I might be over thinking this but I've read almost all of Chapter 10 in the 2018 IBC and commentary and can't find clear wording on this.

In this scenario two exits are required, and you reach the first exit stair under the common path of travel distance, lets say 125' for a R-2 occupancy. However the 2nd exit is still over the max allowed exit access travel distance of 250'. In this scenario it is a double-loaded R-2 apartment building in a horse-shoe shape configuration, with exits at both ends and one in the center.

Common path of travel is the max distance you can travel until you have two-choices to an exit, but does it matter if that 2nd exit is still over 250' away?

Thank you.

 

[Yankee Chronicler]

The code only regulates the maximum length of travel to reach "an" exit -- any exit. As long as there is one exit within the maximum distance from every point in the plan, the travel distance to a second, third, or fourth exit is not regulated.

That said, I don't think your opening sentence makes sense:

In this scenario two exits are required, and you reach the first exit stair under the common path of travel distance, lets say 125' for a R-2 occupancy.

As you subsequently mention, the common path of travel is from a remote point to a point from which you have a choice of two exits in different directions. In your example, if the allowable common path of exit travel is 125 feet, does the plan really make someone travel all the way to the first exit before they have access to a path of travel to the second exit? Common path of travel isn't addressing the complete path to one exit, it's only addressing the distance to where you have a choice of turning left or right.

From the IBC Commentary to 1017.2:

The common path of egress travel addressed in Sections
1006.2.1 and 1006.3.3 is part of the overall exit
access travel distance, with both starting at the same
point. Common path of egress travel stops where the
occupant has a choice of at least two exits, and overall
egress travel distance stops where an occupant gets to
the closest exit.

 

[RLGA]

I think YC covered it pretty well.

From your description of the floor plan ("a horse-shoe shape configuration, with exits at both ends and one in the center), I do not see how you would have a common path of egress travel of 125 feet unless the "exits at both ends" are not exactly at the ends (i.e., inset from the ends of the corridor) and the path of travel within a dwelling unit exceeds 125 feet.

 

[admiralArchArch]

The code only regulates the maximum length of travel to reach "an" exit -- any exit. As long as there is one exit within the maximum distance from every point in the plan, the travel distance to a second, third, or fourth exit is not regulated.

That said, I don't think your opening sentence makes sense:


As you subsequently mention, the common path of travel is from a remote point to a point from which you have a choice of two exits in different directions. In your example, if the allowable common path of exit travel is 125 feet, does the plan really make someone travel all the way to the first exit before they have access to a path of travel to the second exit? Common path of travel isn't addressing the complete path to one exit, it's only addressing the distance to where you have a choice of turning left or right.

From the IBC Commentary to 1017.2:

I think YC covered it pretty well.

From your description of the floor plan ("a horse-shoe shape configuration, with exits at both ends and one in the center), I do not see how you would have a common path of egress travel of 125 feet unless the "exits at both ends" are not exactly at the ends (i.e., inset from the ends of the corridor) and the path of travel within a dwelling unit exceeds 125 feet.

Thank you both. I must be misunderstanding common path of travel. If there is only one direction of travel than there is not a choice of two directions.

As a follow up, any stair/exit that is outside the maximum travel distance to reach that stair would not have occupants counted in its egress capacity. For example, say we have a floor plate of 333 occupants and three exit stairs are provided. Simply dividing the total number of occupants by three is 111 occupants for each stair. But say for 50 occupants, one of those stairs is outside the max travel distance so maybe for each exit stair the occupant load is distributed as 141/142/50 occupants.

Is that logic correct?

 

[RLGA]

Thank you both. I must be misunderstanding common path of travel. If there is only one direction of travel than there is not a choice of two directions.

As a follow up, any stair/exit that is outside the maximum travel distance to reach that stair would not have occupants counted in its egress capacity. For example, say we have a floor plate of 333 occupants and three exit stairs are provided. Simply dividing the total number of occupants by three is 111 occupants for each stair. But say for 50 occupants, one of those stairs is outside the max travel distance so maybe for each exit stair the occupant load is distributed as 141/142/50 occupants.

Is that logic correct?

Here are two examples of a CPET depending on where the "exits at the ends" are located:

This shows the exits at the ends of the corridor. The CPET (red dashed line) is to the unit's entrance, and the point where the occupant can take two paths to two separate exits is marked by the green "X." The travel distance would be measured along the blue dashed line.



Here is a modified example where the exits are near the end of the corridor. The CPET ends (green "X") where the occupant can enter the closest exit or continue to the next available exit in the center of the building. This condition would also have to comply with the dead-end corridor requirements.



As for the latter part of your post, it does not matter if an exit is outside of their travel distance as long as at least one of the exits is within the maximum travel distance. I would still divide the occupant load on the story by three to ensure compliance with IBC Section 1005.5 (2021 edition).

 

[admiralArchArch]

Excellent diagrams, thank you so much for the explanations.