What term describes the areas in a building that are not rent-generating but necessary for the operation of the building?

The term that accurately describes the areas in a building that are not rent-generating but necessary for the operation of the building is "support spaces." Support spaces include areas such as hallways, lobbies, stairwells, restrooms, and mechanical rooms. These spaces facilitate the functioning and access within the property but do not directly contribute to generating income through rent.

Support spaces are crucial for tenants and visitors, providing essential services that support the overall operation and accessibility of the building, even though they do not produce rental income. Understanding the role of these spaces is important for landlords, property managers, and real estate professionals when evaluating the efficiency and functionality of a property.

"Dead space" might imply areas that are completely unusable, while "common areas" generally refer to shared spaces that may have some rental potential in conjunction with another tenant. "Lost areas" is not a standard term used in real estate to describe these types of spaces, making "support spaces" the most appropriate choice.