Net Floor Area is defined as the floor area within the inside perimeter of the outside walls, or the outside walls and fire walls of the building under consideration with deductions for hallways, stairs, closets, thickness of interior walls, columns, or other features.

Net Floor Area is defined as the floor area within the inside perimeter of the outside walls, or the outside walls and fire walls of the building under consideration with deductions for hallways, stairs, closets, thickness of interior walls, columns, or other features.

• A. The floor area within the inside perimeter of the outside walls with deductions for hallways, stairs, closets, thickness of interior walls, columns, or other features.
• B. The floor area within the inside perimeter of the outside walls with no deductions for interior features.
• C. The floor area within the inside perimeter of the outside walls, or the outside walls and fire walls of the building under consideration with deductions for hallways, stairs, closets, thickness of interior walls, columns, or other features.
• D. The area inside exterior walls used for tenant storage.

Answer: (C)

Net floor area is the usable floor space contained inside the building’s exterior boundary, with deductions for features that occupy space or aren’t usable for occupancy. The boundary can be the inside perimeter of the outside walls, or, when fire walls exist, the outside walls and fire walls that define the building. After establishing that boundary, you subtract areas such as hallways, stairs, closets, the thickness of interior walls, columns, and other intrusions. This description exactly matches how NFPA 101 defines net floor area, because it accounts for both boundary scenarios (with or without fire walls) and for subtracting non-usable spaces. If the boundary was described without including fire walls, it would be incomplete. If deductions for interior features weren’t required, the area would overcount usable space. And describing area as simply “tenant storage” would miss the general concept of usable floor area for any occupancy.

Net floor area is the usable floor space contained inside the building’s exterior boundary, with deductions for features that occupy space or aren’t usable for occupancy. The boundary can be the inside perimeter of the outside walls, or, when fire walls exist, the outside walls and fire walls that define the building. After establishing that boundary, you subtract areas such as hallways, stairs, closets, the thickness of interior walls, columns, and other intrusions.

This description exactly matches how NFPA 101 defines net floor area, because it accounts for both boundary scenarios (with or without fire walls) and for subtracting non-usable spaces. If the boundary was described without including fire walls, it would be incomplete. If deductions for interior features weren’t required, the area would overcount usable space. And describing area as simply “tenant storage” would miss the general concept of usable floor area for any occupancy.