‘A Guide for Consistent Measuring in the Building Industry’
The Sixth Edition of the ‘Code’ provides succinct, precise definitions to permit the accurate measurement of buildings and land, the calculation of the sizes (areas and volumes) and the description or specification of land and buildings on a common and consistent basis. The main area terminology used in the particulars on this site refer to
Gross Internal Area (GIA)
Gross Internal Area is the area of a building measured to the internal face of the perimeter walls at each floor level.
Net Internal Area (NIA)
Net Internal Area is the usable area within a building measured to the internal face of the perimeter walls at each floor level.
Here we refer you to the RICS ‘Code of Measuring Practice’ for detailed explanations of what is included & excluded in the measurements, it can be found for sale at the link below: