Calculating Gross Square Footage (GSF) is a fundamental step in real estate and construction, representing the total area of a building. Based on standard definitions, including the provided reference, the calculation involves specific measurements of the building's footprint.
The Gross Square Footage is calculated from the outside of the exterior walls and is inclusive of all space within minus areas that are open to below.
Understanding the Basis of Gross Square Footage
Gross Square Footage provides a comprehensive measure of a building's size. It's essentially the area covered by the building's structure at each floor level. Unlike other measurements that focus on usable space, GSF accounts for the entire enclosed volume (excluding certain voids).
Step-by-Step Calculation
Based on the reference, the calculation of Gross Square Footage follows a clear method:
- Measure from the Outside of the Exterior Walls: Begin by measuring the dimensions of the building from the outer face of its exterior walls on each floor level. This means the measurement includes the thickness of the exterior walls themselves.
- Include All Space Within: Within the perimeter defined by the outside of the exterior walls, all space within is included in the calculation. This covers everything inside the building envelope on that floor level.
- Subtract Areas Open to Below: From the total area calculated in the previous steps, subtract any areas that are open to the floor below. These are typically voids or openings that extend through the floor, such as stairwells, elevator shafts, or double-height spaces that look down onto the floor below.
- Example: If a building floor measures 50 feet by 100 feet from the outside of the exterior walls, the initial area is 5,000 square feet. If there is a 10x10 foot opening for a stairwell that is open to the floor below, you would subtract 100 square feet from the total for that floor.
Gross vs. Net Square Footage
It's important to distinguish Gross Square Footage from Net Square Footage (NSF), as they measure different aspects of a building's area.
| Feature | Gross Square Footage (GSF) | Net Square Footage (NSF) |
|---|---|---|
| Measurement Point | From the outside of the exterior walls | Sum of individual room/area footages on a floor |
| Scope | Inclusive of all space within the exterior walls | Total square footage of all the rooms/areas on a floor (includes assignable and non-assignable rooms) |
| Exclusions | Minus areas that are open to below | Generally includes all defined rooms/areas; exclusions vary by standard but the reference implies everything within rooms |
| Purpose | Represents total building size; used for construction cost estimates, zoning, etc. | Represents usable or functional space within rooms; used for leasing, space planning, etc. |
As defined in the reference, Net Square Footage is the total square footage of all the rooms/areas on a floor, encompassing both assignable and non-assignable spaces. GSF provides the overall shell size, while NSF focuses on the areas divided into specific rooms or functions.
Practical Considerations
When calculating GSF:
- Ensure measurements are taken from the outermost face of the exterior walls at each floor level.
- Be diligent in identifying and subtracting all voids that are open to the floor below.
- Consistent application of the measurement standard is crucial for accuracy, especially when comparing different buildings or floors.
Understanding and accurately calculating Gross Square Footage is vital for various purposes, including property valuation, development planning, and compliance with building codes.
