How land for development purposes is measured globally

For all that it is a traditional practice, land measurement would benefit from a standard approach around the world, as is the aim of RICS guidance


  • Jonathan Manns

02 July 2019

Ancient Egyptian surveyors using cord to measure. Best practice has since moved on, and in the 21st century surveyors around the world are now looking for more consistency. ©De Agostini Picture Library/Scala, Florence

When approached by RICS to draft guidance on the measurement of land for planning and development purposes, my first reaction was simply – why? After all, while fundamental to a surveyors' work, it's also something we've been doing for millennia.

The Egyptians began surveying land to set out structure and boundaries for tax purposes as early as 1400 BCE. The practice has carried on through the centuries and I have spent my entire career referring to land measurements without too much confusion or complication. Surely we've managed fine without guidance?

It didnt take long to realise that we have been muddling through.I found out as much when I called three local authorities asking how they measured land for planning and development purposes to apply their policies and received three different answers.
  • One measured what was shown on the planning site area drawing.
  • Another measured to the edge of the site plus an extension to the middle of any adjoining roads.
  • A third measured the part of the site where building took place.

These were off-the-cuff responses, but it's clear that measurement of land is less straightforward than you might assume. Next, I trawled the internet, which highlighted variations in the measurement of land in different parts of the world in relation to development proposals. The search also flagged up the extent to which metrics for assessing proposals, such as density, are applied differently in the different local authorities. As we move from place to place, we're not always comparing apples with apples.

"Measurement of land is less straightforward than you might assume"

Its not only places that work differently, but people as well. Pick up a copy of any property magazine to see the wider professional implications: it will be replete with the usual advertisements for land, putting the site area that can be acquired front and centre. While this information will be relevant to a purchaser or agent, there is not necessarily any correlation between the area of land being marketed and that for which permission to build might be sought. Having different measurements isn't itself problematic but does create misunderstanding, not least when it comes to valuation.

Irrespective of expertise, the surveying profession largely depends on colloquial references to 'the site' and 'site area'. In some instances this has legal connotations, in others it does not. In some it relates to planning and development proposals, in others it does not. Standardised definitions will help to clarify these issues.  Surveyors have been effective in their roles, but depend on context-specific and ultimately inconsistent approaches. RICS should therefore intervene to ensure matters are properly regulated.

Changes afoot

A change in the way that surveyors work is inevitable and unavoidable. Standards enable us all at each stage of the development process to compare properties accurately. Whether to value, transact on or develop a site, it is just as important for the land as the buildings on it that measurement be carried out consistently and uniformly.

The guidance is intended to provide surveyors with necessary new standards for best practice. It proposes five definitions for terminology as follows.

  • Land area

    This should be used to refer to the legal title area of land and is of particular relevance to agents and lawyers, as it is the legally demised area of land being marketed.

  • Site area

    This should be used to refer to the area of land used for planning application purposes and is of importance to those involved in the development process, as it is the area to which any permission for development relates.

  • Net development area

    This should be used to refer to the area from which financial value is directly derived by virtue of either being income-producing or for sale, and is of relevance to development surveyors and valuers.

  • Plot ratio

    This is the ratio of Gross External Area (GEA) of a building or buildings at each floor area under the International Property Measurement Standards to the site area, and is already used as a standard metric for planning and design in certain sectors and jurisdictions.

  • Site coverage

    This is the ratio of the building footprint's GEA to the site area at ground-floor level, and again is already a standard metric for planning and design in certain sectors and jurisdictions.

The implications for development surveyors, planners and architects are considerable: once published, the guidance note will become best practice for consistent calculation of land measurement and associated metrics. The impact on valuers and agents should also be acknowledged, as it has the potential to change the way in which values are reported to clients and development sites are marketed.

Jonathan Manns MRICS is board director and head of planning and development at Rockwell Property

Related competencies include: Development appraisals, Legal/regulatory compliance, Surveying and mapping

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