Gross external floor area (GEFA) is the total floor area of a building measured externally, in accordance with IPMS 1 under the International Property Measurement Standards.
IPMS 1 measures the area of each floor to the outer perimeter of the external walls, so it includes the thickness of the external walls as well as all internal space. It is broadly comparable to the gross external area (GEA) used under the RICS Code of Measuring Practice, and in the UK both are applied through the RICS professional statement on property measurement. GEFA is mainly used for planning purposes, site coverage calculations and, for some building types such as houses, cost estimating. For the QS, the important point is consistency: always state which measurement basis has been used, and do not mix rates based on external and internal areas when benchmarking costs.
Related terms: Gross Internal Floor Area, IPMS, Net Internal Area, Code of Measuring Practice.
