What percentage reduction in required capacity or width is permissible when more than one exit is required and one exit is lost?

The permissible percentage reduction in required capacity or width when one exit is lost is typically established by building codes and safety regulations, which recognize the importance of maintaining a safe egress system. When more than one exit is mandated, the legal framework allows for a reduction in exit capacity or width, assuming that the remaining exits can adequately accommodate the occupants of the building in an emergency.

In this case, a reduction of 50% is standard practice, primarily to ensure that the remaining exit(s) are still adequate to handle the expected evacuation load. This percentage strikes a balance between safety and practicality, ensuring that even with a single exit available, there is a sufficient capacity for the remaining occupants to exit the building safely and efficiently.

The other percentages would impose stricter limitations that may not be practical for maintaining operable safety measures in commercial buildings. Thus, recognizing a 50% reduction aligns with safety regulations while still ensuring an adequate means of egress for occupants.