Last edited 08 Oct 2016

Gross external area GEA

The area of a building can be measured in a number of different ways:

It is very important to be clear about which measure is being used, for example in property sales, planning applications, building regulations applications, lease negotiations, rating valuations and so on.

The UK government’s Valuation Office Agency (VOA) Code of measuring practice: definitions for rating purposes suggests that ‘gross external area’ refers to the whole area of a building taking each floor into account, including perimeter walls. This includes:

  • Perimeter wall thickness and external projections.
  • Areas occupied by internal walls (whether structural or not) and partitions.
  • Columns, piers, chimney breasts, stairwells, lift wells and so on.
  • Lift rooms, plant rooms, tank rooms, fuel stores, whether or not above roof level.
  • Open-sided covered areas (should be stated separately).

Gross external area excludes:

  • Open balconies.
  • Open fire escapes.
  • Open sided covered ways.
  • Open vehicle parking areas, terraces and so on.
  • Minor canopies
  • Any area with a headroom of less than 1.5m (except under stairways).
  • Any area under the control of service or other external authorities

It suggests that party walls should be measured to their centre lines.

The VOA Code of measuring practice is in general agreement with RICS Guidance Note, A guide for Property Professionals, 6th Edition Code of measuring practice 2007, other than, areas with a headroom of less than 1.5m which are excluded from the VOA measurement.

[edit] Find out more

[edit] Related articles on Designing Buildings Wiki