California IDEX Practice Exam 2025 - Free IDEX Practice Questions and Study Guide

In commercial design, incidental use areas are spaces that are typically not the primary function of a building but are still essential for the overall operation. A storage room exceeding 100 square feet often fits this description, as it may not be the main focus of the design but serves a necessary function for the operation of the facility, such as storing supplies, equipment, or materials.

Choosing a storage room over 100 square feet as the correct answer reflects an understanding of how incidental areas can contribute to the functionality of a space without being central to its purpose. These areas are often subject to specific building codes and regulations, particularly regarding fire safety and occupancy, which further emphasizes their significance in commercial design.

Other options, while related to commercial spaces, do not embody the same incidental nature. Public restrooms and meeting rooms are usually critical to the main functions of a commercial building, while employee workstations are essential direct-use areas within the design. Therefore, the characterization of the storage room as an incidental use area stands out as the correct choice.