Section 4: definitions

Element: A major physical part of a building that fulfils a specific function, or functions, irrespective of its design, specification or construction.

Dates

Base date: The contractual date at which the pricing levels have been set. This is defined as 'Date of Tender' in editions of JCT contracts. Under formulae fluctuating contracts it is the base month.

Date for receipt of tenders: The deadline for the receipt of competitive tenders or the date of agreement of negotiated price.

Date of acceptance: The date the price was contractually agreed.

Date of possession of site: The date the site was available to the contractor.

Floor areas

Gross internal floor area (GIFA): Area of a building measured to the internal face of the perimeter walls at each floor level (see notes).

Notes:

1. The definition of gross internal floor area is taken from the RICS Code of Measuring Practice 6th Edition 2007.
2. The GIFA excludes the thickness of perimeter walls, but includes the thickness of all internal walls. Therefore, you need to identify what constitutes a separate building, e.g. the sum of the GIFA of a terrace of buildings, treated as separate buildings, will be different from the terrace treated as a single building.
3. Areas of open ground floors and the like should be excluded.
4. 'Internal face' means the structural wall or plaster coat applied to the structural wall, not the surface of internal linings installed by the occupier.
5. Include lift rooms etc. if housed in a roofed structure having the appearance of permanence (e.g. made of brick or similar building material). Exclude areas covered by enclosures designed solely to mask plant, rooflines, etc.
6. Note the presence of steps or changes in floor levels.
7. Attention is drawn to the exclusion of voids over atria at upper levels and the inclusion of voids over stairs etc. Where an atrium-like space is formed to create an entrance feature, and this also accommodates a staircase, this does not become a stairwell but remains an atrium measurable at base level only.
8. Include walkways across an atrium at upper levels in the measurement of upper floors.
9. Include areas in the roof space intended for use with permanent access in the measurement of upper floors. Measure to internal face of the roof at floor level.
10. Treat re-entrant balconies (i.e. open-sided balconies within the predominant line of the external wall) as open-sided balconies and exclude them.

Area of lowest floor: Area of lowest floor measured to the internal face of the external wall (as for gross internal floor area) (m2).

Basement floor area: Area of all floors below ground floor measured as for gross internal floor aea. Note: This is not the same as the 'area of lowest floor'.

Ground floor area: Area of the floor nearest the level of the outside ground measured as for gross internal floor area.

Upper floor area: Area of all floors above ground floor measured as for gross internal floor area. Note: This is not the same as the 'area of upper floors'. See measurement rule for the element unit quantity in element 2.2 Upper Floors.

Note: The sum of basement, ground and upper floor areas should equal the gross internal floor area.

Usable floor area: Total area of all enclosed spaces fulfilling the main functional requirements of the building (e.g. office space, shop space, public house drinking areas, etc). Where this is defined by the client, state the definition.

Circulation floor area: Total area of all enclosed spaces forming entrance halls, corridors, staircases, lift wells, connecting links and the like.

Ancillary floor area: Total area of all enclosed spaces for lavatories, cloakrooms, cleaners' rooms, lift, plant and tank rooms and the like, supplementary to the main function of the building.

Internal divisions floor area: The area occupied by partitions, columns, chimney breasts, internal structural or party walls.

Note: The sum of the usable, circulation, ancillary and internal divisions floor areas should equal the gross internal floor area.

Net floor area: Sum of usable, circulation and ancillary floor areas. Note: This is not the same as the net internal area defined in the RICS Code of Measuring Practice.

Floor spaces not enclosed: Spaces fulfilling a requirement of the building, which are not enclosed spaces, such as open ground floors, open covered ways, open-sided balconies and the like, should be shown separately and measured by notionally enclosing the open sides. Exclude eaves, overhangs, sun shading, awnings and the like.

Floor area of internal spaces: Where the area of an internal space is given, e.g. to calculate treated area or volume for air conditioning, or to define the area of a department, measure to the internal face of the enclosing external and internal walls as for gross internal floor area. Note: This means that the sum of internal spaces will not be the same as the GIFA.

Roof area: Plan area of a designed roof measured across the eaves overhang or to the inner face of parapet walls. Includes area covered by rooflights. Sloping and pitched roofs should be measured on plan area. Note: This is not the same as the element unit quantity for 2.3 Roof.

Area of vertical enclosure (external wall area): The wall area of all the enclosed spaces fulfilling the functional requirements of the building, measured on the internal face of external walls and overall windows and doors, etc. This should equal the sum of the element unit quantities for 2.5 External Walls and 2.6 Windows and External Doors.

Wall to floor ratio: Calculated by dividing the area of vertical enclosure by the gross internal floor area to 3 decimal places.

Element unit quantity: The measurement of each element as given in the Element Definitions. 

Treated floor area, floor area serviced: The floor area intended to be covered by an installation or system, measured to the internal face of enclosing walls.

Element ratios: Calculated by dividing the element unit quantity by the gross internal floor area to 3 decimal places. Note: In the case of buildings, where only a part is treated or served by mechanical or electrical installations, indication of this is given by a ratio as follows:

Where Tm2 is the total area in square metres of the various compartments treated or served.

Storey height: Height measured from floor finish to floor finish. For single-storey buildings and top floor of multi-storied buildings, measure the height from floor finish to underside of ceiling finish.

Internal cube: All enclosed spaces fulfilling the requirements of the building. Measure the cube as the gross internal floor area of each floor multiplied by its storey height. Exclude any spaces fulfilling a requirement of the building, which are not enclosed spaces, such as open ground floors, open covered ways and the like, which should be shown separately giving the notional cubic content of each, ascertained by notionally enclosing the open top or sides.

Functional unit: Express the functional unit(s) of the building as a number of units of accommodation, (e.g. seats in churches, school places, persons per dwelling, etc.) or usable floor area of accommodation provided. Where the functional unit is defined by the client, state the definition; see Recommended functional units.

Site area: Total site area, excluding any areas used temporarily for the works that do not form part of the delivered site. Note: This is not the same as the element unit quantity for 8 External Works.