RICS Code of Measuring Practice: GEA

Measurement Practice

• The RICS Code of Measuring Practice, 6th edition (2007) provides three core definitions: Gross External Area (GEA), Gross Internal Area (GIA), and Net Internal Area (NIA).

Gross External Area (GEA)

• Recommended for: building cost estimations, town planning applications, and rating and council tax bands.
• Defined as the area of a building measured externally at each floor level.

Gross Internal Area (GIA)

• Recommended for: building cost estimation, marketing and valuation of industrial buildings, and property management.
• Defined as the area of a building measured to the internal face of the perimeter walls at each floor level.
• Note: Internal face refers to the brick/block or plaster coat applied to the brick/block work, not the surface of internal linings installed by the occupier.

Net Internal Area (NIA)

• Recommended for: marketing and valuation of shops, supermarkets, and offices, and rating shops.
• Defined as the usable area within a building measured to the internal face of the perimeter walls at each floor level.
• Note: An area is usable if it can be used for any sensible purpose in connection with the purposes for which the premises are to be used.

Standard Methods of Measurement of Building Works (SMM7)

• First appeared in 1922 and aimed to bring uniformity to the measurement and pricing of building works.
• Traditionally presented in trade format.

Key Principles of the RICS Code

• The bill of quantities is traditionally presented in trade format, following the order of SMM7.
• Managing the measurement process involves a group approach, including substructure, frame, upper floors, external walls, windows, staircases, roof, internal doors, doors, internal finishes, services, and drainage.

Taking-off Construction Works

• Refers to the process of identifying and quantifying elements of construction works that can be measured and priced.
• Used to produce bills of quantities for tenderers and to determine quantities required by contractors and subcontractors.
• Involves the use of timesing, dotting on, and waste calculations.

Timesing

• A method used to multiply measurements and calculate quantities.
• Involves setting down additional numbers in the timesing column.

Dotting On

• A method used to add dimensions together in the timesing column.
• Involves positioning numbers diagonally in the column with a dot between them.

Waste Calculation

• Important to write down calculations done to work out dimensions in the description column.
• Allows reviewers to trace back the process by which final figures were calculated.

Alterations

• Incorrect dimensions should be neatly crossed out with ‘nil’ written alongside in the squaring column.
• Indicates that the dimensions are cancelled.

Dimensions for Taking Off

• Can be in the form of cubic measurements, square measurements, linear measurements, or enumerated items.
• Should be set down in order of horizontal length, horizontal width or breadth, and vertical depth or height.

Taking-off Columns

• Timesing column: gives the factor of multiplication for the measurements in the dimension column.
• Dimension column: where the measurements are set down.
• Squaring column: where the calculated volumes, areas, and so on, are set out.
• Description column: where the description of the work item in relation to the measurements is written.

Test your knowledge of the RICS code of measuring practice, 6th edition, specifically Gross External Area (GEA) and its applications in building cost estimation, town planning, and rating and council tax bands.