Last edited 30 Aug 2020

Gross internal area GIA

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

It is very important when describing the area of a building to be clear about which measure is being used, for example in planning applications, building regulation applications, property sales, 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 internal area includes:

Gross internal area excludes:

The VOA code 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.

NB: NRM1: Order of cost estimating and cost planning for capital building work, defines ‘gross internal floor area’ (GIFA) (or gross internal area (GIA)) as:

‘…the area of a building measured to the internal face of the perimeter walls at each floor level. The rules of measurement of gross internal floor area are defined in the latest edition of the RICS Code of Measuring Practice.’

According to ‘Elemental Standard Form of Cost Analysis, Principles, Instructions, Elements and Definitions, 4th (NRM) Edition’ written by RICS in 2012 and published by BCIS, GIFA includes:

It excludes:

And that:


[edit] Related articles on Designing Buildings Wiki


A question - what about undercroft spaces? Meaning an open area of building that has the same building above it and columns coming down to ground, with entrance to the building at ground.

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