Gross External Area (GEA) is a fundamental measurement in property, representing the total area of a building calculated by measuring its exterior dimensions at each floor level.
Understanding Gross External Area (GEA)
GEA provides a comprehensive measure of a building's overall footprint, encompassing not just the usable space but also the structural elements. It is distinct from other measurements like Gross Internal Area (GIA) or Net Internal Area (NIA) because it includes the thickness of the external walls. This metric is commonly used in various stages of a building's lifecycle, from initial planning and cost estimation to valuation and rating purposes.
The Measurement Process for GEA
To determine the Gross External Area, a building is measured from its outer perimeter at every floor. This means capturing the full extent of the building's shell, including all areas within the external face of the perimeter walls.
The calculation for GEA typically includes:
- The full thickness of the perimeter walls.
- All areas occupied by internal walls and partitions.
- Structural elements such as columns and piers.
- Vertical shafts like chimney breasts, stairwells, and lift-wells.
- Any other similar enclosed areas within the building's external shell.
Key Components Included in GEA
GEA is designed to account for the entire structural volume of a building. The table below illustrates the typical inclusions:
| Component | Description |
|---|---|
| Perimeter Wall Thicknesses | The full width of the external walls that define the building's boundary at each floor level. |
| Internal Walls & Partitions | The area taken up by all dividing walls and partitions within the building, whether load-bearing or not. |
| Structural Elements | Features like columns, piers, and any other integral structural supports. |
| Vertical Penetrations | Spaces such as chimney breasts, stairwells, and lift-wells that vertically traverse multiple floors. |
Practical Applications and Significance
GEA serves a crucial role in the property and construction industries. It offers a consistent basis for comparison and calculation, particularly in:
- Valuation and Rating: For assessing property taxes or market value, as it reflects the overall scale of the structure.
- Planning and Development: To understand the building's impact on a site and ensure compliance with zoning regulations.
- Construction Costing: Providing a broad metric for estimating construction costs per square meter/foot, especially in early project stages.
- Feasibility Studies: Helping developers evaluate the potential of a project based on the total buildable area.
For a more comprehensive understanding of property measurement standards, you can refer to established guidelines such as those provided by the Royal Institution of Chartered Surveyors (RICS).
Distinguishing GEA from Other Metrics
It's important to understand that GEA differs from other common property measurements:
- Gross Internal Area (GIA): Measured to the internal face of the perimeter walls at each floor level. It includes internal walls but excludes external walls.
- Net Internal Area (NIA): Represents the usable area within a building, typically excluding structural elements, common parts, and vertical penetrations.
GEA is fundamentally about the external envelope, making it the largest area measurement for a given building.
