IPMS: introducing Residential Buildings

Homing in: IPMS Residential

3 January 2017

Alexander Aronsohn introduces the newly published IPMS Residential Buildings

In September 2016 the International Property Measurement Standards Coalition (IPMSC) published IPMS Residential Buildings, an open-source document that is available to download. It is the second building class in this suite of standards, following a second stage of consultation that concluded in April 2016.

Definitions and revisions

The IPMSC Standards Setting Committee (SSC) has amended or added the following definitions:

  • Balcony: an external platform at an upper floor level with a balustrade to the open sides projecting from or recessed from an External Wall and including in this definition generally accessible rooftop terraces, external galleries and loggia.
  • Covered Area: the extent at ground level of the area of Building covered by 1 or more roofs, the perimeter of which, sometimes referred to as the drip line, is the outermost structural extension, exclusive of ornamental overhangs.
  • Mezzanine: an intermediate or partial storey, other than a Catwalk, between the floor levels or roof of a Building and usually fully or partially open on 1 or more sides.
  • Patio: a paved or floored terrace, adjacent to a Building, that may or may not be covered by an independent framework.
  • Permanent Mezzanine: a Mezzanine that is an integral part of the structure of a Building.
  • Residential Building: a Building predominantly used for residential purposes, whether or not part of the Building is used for other purposes.
  • Veranda: an open or partly enclosed area on the outside of a Building at ground level (Level 0), and covered by a roof that is an integral part of the Building. In response to the feedback it received from the consultation, the IPMSC SSC has also revised the following definitions for both Internal Dominant Face (IDF) and IDF (Internal Wall Section), the latter of which was previously called Vertical Section, in order to make these more user-friendly.
  • IDF: the inside Finished Surface comprising more than 50% of the floor-to-ceiling height for each IDF Wall Section. If such does not occur, then the Finished Surface is deemed to be the IDF.
  • IDF Wall Section: each internal finish of a section of an External Wall, ignoring the existence of any columns, that is either recessed from or protrudes from its adjacent section.

The revised standard also includes a new section 1.4, entitled Floor Level Designation, to deal with a lack of global market consistency. IPMS Residential Buildings states:

'to provide consistency in IPMS, the primary ground level has been designated Level 0, with the levels above as Level 1, 2, 3 etc. and levels below the primary ground level as Level –1, –2, –3, etc.'

The standard also identifies a new Limited-Use Area called 'Example 5 – Area difference from Covered Area'. It explains that,

'where a Sheltered Area is not functional for the primary use, this part of the Covered Area may be classified as limited-use area'.


The format of IPMS Residential Buildings marks a change from the one that was used for IPMS Office Buildings; in addition to Part 1 – Aim and Scope of the Standards, Part 2 – Principles of Measurement IPMS 2 and Part 3 – IPMS Standards, there is a new Part 4 – Technical Section, which contains the IPMS Residential Component Areas and the IDF technical diagrams.

IPMS Residential Buildings includes separate floorplans for Residential Apartments and Residential Dwellings

IPMS Residential Component Areas have now been revised so the sum of the Component Areas now equals IPMS 1, and the sum of the Component Areas minus the new Component Area B1 (External Walls) equals IPMS 2 Residential Buildings. The new sub-categories of Component Area B are as follows.

  1. IPMS Residential Component Area B1, external walls, are defined as: 'The external enclosure of a building, which comprises the area between the IDF and the outside face of the building.'
  2. IPMS Residential Component Area B2, internal structural elements, comprise all internal structural walls and columns.
  3. IPMS Residential Component Area B3, internal non-structural elements, comprise all internal full-height permanent walls other than those included in Component Areas B1 and B2.

In addition to the revised Component Area B, there is also a new Component Area G called Living Space, which is defined as 'the area available for use by residential occupiers. Some of the Component Areas in this table can be further used for IPMS 3 if required.'

IPMS Residential Buildings still comprises the following three main measurement standards:

  • IPMS 1
  • IPMS 2 – Residential Buildings
  • IPMS 3 – Residential Buildings.

IPMS 1 can be used by parties for planning purposes or the summary costing of development proposals, and is defined as:

'the sum of the areas of each floor level of a building measured to the outer perimeter of external construction features. It is the same for all classes of building. In many markets, but not universally, this is known as gross external area.'

IPMS 2 – Residential can assist the property sector in making efficient use of space and benchmarking data, and is defined as: 'The sum of the areas of each floor level of a residential building measured to the IDF.' However, in respect of IPMS 3 – Residential Buildings, the SSC identified 3 different measurement bases that were required to meet global market needs: IPMS 3A – Residential, IPMS 3B – Residential and IPMS 3C – Residential. Some markets require only 1 of these measurement bases, but others may use 2 or more for different purposes.

Furthermore, IPMS Residential Buildings includes separate floorplans for Residential Apartments and Residential Dwellings in order to enable the general public to use the standard to measure their houses.

IPMS 3A – Residential is the area in exclusive occupation measured to the outer face of the External Wall for detached dwellings, and to the outer face of the External Wall and the centre line of shared walls between occupants for attached dwellings.

IPMS 3B is the area in exclusive occupation, including the Floor Area occupied by internal walls and columns, measured to the IDF and the Finished Surface of internal perimeter walls.

IPMS 3C is the area in exclusive occupation, excluding the Floor Area occupied by full-height internal walls and columns, measured to the IDF and the Finished Surface of all the full-height internal walls.

The IPMSC SSC is currently working on drafting IPMS Retail Buildings, while consultation on IPMS Industrial Buildings concluded in September 2016.

Alexander Aronsohn FRICS is RICS Director of Technical International Standards and Executive Secretary of the IPMS SSC

Further information