Net Internal AreaNet Internal Area

Net Internal Area (NIA) is defined as the usable floor area within a building, inside the internal face of perimeter walls. Used as the basis for Property Valuation, Rating, Property Management and Marketing, Net Internal Area (NIA) surveys are essential for all commercial and residential properties.


In determining whether an area of a property is usable or not, and can be counted towards Net Internal Area, the correct approach is to ascertain whether the area can be used for any sensible purpose in connection with the purposes for which the property is to be used. This is so, whether or not the area is “floor”. If the space is “usable” on this basis, it should be calculated as part of the NIA. Specific details, inclusions and exclusions are detailed in the RICS Code of Measuring Practice, Guidance Notes.


The purpose of the Code is to provide 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. This may be required for valuation, management, conveyancing, planning, taxation, sale, letting, or acquisition purposes.



We have amassed considerable experience providing NIA surveys to retail, residential, office, leisure and industrial clients who are located throughout the UK and Ireland.


We will provide you with detailed plans and reports in accordance with the Royal Institution of Chartered Surveyors (RICS) code of Measuring Practice and to meet with your own specific requirements. The Duty of Care offered will guarantee our work is in accordance with the RICS code of measuring practice and the accuracy and detail can be wholly relied upon.



  • Accurate net floor areas for all building layouts

  • 2D Floor plans with the required level of detail


  • Clear Floor area reports and calculations


With over 27 years experience in land and building surveying, our success to date is attributed to many factors, however it is our accuracy and high levels of quality control in addition to our client centred consultancy that we believe to be the core to our success.


Murphy Surveys are widely regarded as one of the most experienced, professional, innovative and technically proficient surveying companies in the UK.