The Gross Areas of a Building: Methods of Measurement
In 2009, BOMA International published "The Gross Areas of a Building: Methods of Measurement". The document is primarily concerned with the appraisal, valuation, replacement, and construction costing for buildings of all types. Using the standard, any building can be measured, including office, retail, industrial, residential and institutional buildings. The standard outlines two distinct measurement methodologies, called "Construction Gross Area" and "Exterior Gross Area".
Construction Gross Area (CGA)
This method includes all of the areas measured in the Exterior Gross Area method but also includes unenclosed areas within the building perimeter that has a structural floor, or are covered by a roof or canopy. This method is useful for determining construction and replacement costs of a building.
Exterior Gross Area (EGA)
This method is similar to BOMA 1996 Gross Building Area (which has been removed from the 2010 office standard). Exterior Gross Area is determined by measuring to the outside surface of exterior walls for each floor without deduction. It includes enclosed structured parking but excludes the roof level of a parking structure. Exterior Gross Area is most often used for tax assessment, but it may also be used when leasing an entire buildng to a single tenant; as long as both parties agree upon it's suitability.