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Gross Floor Area (GFA)

The sum of the floor areas of all the spaces within the building, with no exclusions. The total area within the perimeter of the outside walls.

The total floor area of a building, including all public and private spaces. the following spaces are considered outside the building and are not part of GFA:

  • Balconies
  • Decks
  • Patios
The area contained within the external walls of the building measured at each floor level (including any floor below the level of the ground), together with the area of each balcony in the building.

Alternative Scopes
The basis for calculating GFA may vary between owner groups and sometimes the GFA excludes the parking garage.
  • All areas within the external walls, including the parkade (GFA)
  • All areas within the external walls, excluding the parkade (GFAxP)
Sometimes the following areas are excluded from the calculation of GFA, which results in a GFAx or NFAx:
  • Parking garage
  • Air shafts
  • Elevator shaft

GFA is
determined through drawing takeoffs or field takeoffs and is used in quantity takeoffs.

GFA has the following applications.

Management Principles
Gross Floor Area is used in benchmarking analysis when making comparisons between buildings.

Space efficiency is simply defined as the ratio of NFA to GFA
Fig. Hierarchy of floor areas ranging from gross floor area (GFA to various types of net floor area (NFA).

Fig. Gross floor area of a high rise building (shown in blue), which does not exclude any spaces whatsoever.

1  1
Fig. The variety of rooms within a building.

Fig.  Mechanical room.

See also:

Floor area gross

Total floor area of all floors of a building calculated with the external dimensions of the building including structures, partitions, corridors, stairs.

Floor area net

Sum of all areas between the vertical building components (walls, partitions,…), i.e. gross floor area reduced by the area for structural components.

Floor area usable

The fraction of the net floor area for the intended use of the building, i.e. net floor area reduced by circulation areas (corridors, stairs etc.) and functional areas (WCs, storage rooms etc.).

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