I recently posted an exercise that allowed iDigHardware readers to use what you’ve learned about egress requirements to answer some questions about a swimming pool enclosure (original post, answers). A question arose regarding the required exit access doors:
If an area requires two or more exit access doors because of the calculated occupant load, how far apart do those egress doors need to be?
In Chapter 10 – Means of Egress, the IBC addresses remoteness of exits in a section called Exit and Exit Access Doorway Configuration. This section states that when 2 exits are required, they must be located at a distance of 1/2 of the diagonal measurement of the area served, or 1/3 of the diagonal measurement if the building is equipped throughout with an automatic sprinkler system. In the swimming pool example, the room measured 60 feet x 127 feet, which would have a diagonal measurement of 140.46 feet (here’s a calculator). If the building did not have a sprinkler system, the 2 exits would need to be at least 70.23 feet apart (140.46 feet / 2)…in the example the building did have a sprinkler system so the 2 doors would have to be at least 46.82 feet apart (140.46 feet / 3).
The intent of this requirement is to ensure that building occupants have another option if one exit is blocked (some areas only require one exit). If more than 2 exit access doors are required to accommodate the calculated occupant load of a space, 2 doors must meet the remoteness measurement above, and the additional doors must be located a reasonable distance apart so that if one becomes blocked, the others will be available. The measurement can be taken at any point in the door width; many AHJs measure to the center of the opening but this is not specifically required by the IBC.