CIL measurements


CIL refers to the Royal Institute of Chartered Surveyors (RICS) code for measuring gross internal floor area. Planning applications ask for gross external measurements. The main differences are set out below.

CC Planning fee floor space definition (Gross External Area)

  • areas occupied by internal walls and partitions
  • columns, piers, chimney breasts, stairwells and the like
  • lift rooms; plant rooms; tank rooms; fuel stores
  • balconies
  • mezzanines
  • terraces
  • stores/bin stores
  • enclosed external areas eg compounds and external sales areas. (this also includes areas where the proposed development creates an enclosed area as a result of building works. And this area becomes usable space eg quadrants within schools and office buildings)
  • perimeter wall thickness and projections (party walls are to be measured to their centre line)
  • open sided covered areas eg car ports and enclosed car  parking areas.

In addition to the above any areas set aside for storing equipment/vehicles/objects that can be moved in and out can be classed as usable floor area. They can be included in any floor space calculation for fee calculation purposes.

RICS definition of Gross Internal Area (used for CIL)

  • areas occupied by internal walls and partitions
  • columns, piers chimney breasts, stairwells, lift-wells, other internal projections, vertical ducts, and the like
  • lift rooms, plant rooms, fuel stores, tank rooms which are housed in a covered structure of a permanent nature, whether or not above main roof level
  • internal open sided balconies, walkways, and the like
  • mezzanine areas intended for use with permanent access
  • atria and entrance halls with clear height above, measured at base level only
  • structural, raked or stepped floors are treated as a level floor measured horizontally
  • horizontal floors with permanent access below structural, raked or stepped floors
  • corridors of a permanent essential nature (eg fire corridors, smoke lobbies, etc)
  • areas in the roof space intended for use with permanent access (BCIS)
  • service accommodation such as toilets, toilet lobbies, bathrooms, showers, changing rooms, cleaners’ rooms and the like
  • projection rooms
  • voids over stairwells and lift shafts on upper floors
  • loading bays
  • areas with a headroom of less than 1.5m
  • pavement vaults
  • garages
  • conservatories (BCIS)

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