What is the term for the total volume of space that can be occupied by a proposed structure above grade level?

The correct term for the total volume of space that can be occupied by a proposed structure above grade level is indeed defined as "allowable maximum building volume." This term encompasses the three-dimensional space a building can occupy, taking into account not only the height but also the other dimensions that define the structure's overall bulk.

In building regulations, zoning laws often establish limits on this volume to manage the density and appearance of developments within a given area. By defining the maximum volume, these regulations help maintain harmony within the environment and ensure that buildings do not overwhelm their surroundings.

In contrast, building height refers specifically to how tall a structure is, while building footprint focuses on the area of land that the structure covers at ground level. Building area generally refers to the total area of all floors within a building. Each of these terms relates to different aspects of building design, but they do not fully encompass the total volume of space above grade, which is why "allowable maximum building volume" is the most accurate choice in this context.