For areas having fixed seats and aisles, the occupant load must be determined by the number of fixed seats installed therein.

The statement is true because, in spaces that are specifically designed for fixed seating, such as theaters, auditoriums, or assembly areas, the occupant load calculation is directly based on the number of fixed seats. This approach is in line with building and safety codes, which mandate that when fixed seats are present, they dictate how many individuals can safely occupy that space.

The rationale behind this guideline is rooted in safety and egress considerations. Fixed seating arrangements lead to set pathways for movement, and the ability to exit the facility efficiently in case of an emergency. Moreover, having a clear standard aids in determining how many people can be safely accommodated without risking overcrowding, which could hinder evacuation and increase the potential for accidents.

In contrast, if there are no fixed seats or if the seating is designed to be movable, occupant loads may be determined by different criteria, such as area per person, reflecting a more flexible use of the space.