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Unit 13 �Measurement Techniques �in Construction

Dr Adewale Abimbola, FHEA, GMICE.

www.edulibrary.co.uk

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Aim: �Introduction to taking off quantities (2)

Define important measurement terminologies.

Discuss the reasons why we take off quantities

Objectives: At the end of the lesson, the students should be able to:

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Definition - Recap�

  • Quantity take-offs are a detailed measurement of materials, labour, and other resources required to complete a construction project.
  • Purpose of Quantity take-offs: to create a comprehensive list of all the components and quantities needed for a project, which can then be used for various purposes, including cost estimation, procurement, and project planning.
  • They are developed by an estimator/quantity surveyor during the pre-construction phase. They use construction plans, drawings, specifications, and sometimes specialised software to calculate the quantities accurately.

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Taking-off Quantities - Reasons

  • To produce bills of quantities
  • A bill of quantities (BOQ) is a document used in tendering in the construction industry in which materials, parts, and labour (and their costs) are itemised (Fig. 1).
  • Detailed measurements/quantities are taken from the contract drawings and specification (Fig. 2). These are then systematically itemised in the dimension paper, which are later used to produce bills of quantities.

Figure 2. An example of a specification for a substructure project.

Figure 1. Sample of a bill of quantities.

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Taking-off Quantities - Reasons

  • To produce bills of quantities
  • The New Rules of Measurement (NRM) and Civil Engineering Standard Method of Measurements (CESMM) are used to standardise the description of the building/civil engineering quantities itemised in the dimension paper (Fig. 3).

Figure 3. An example of a dimension paper.

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Taking-off Quantities - Reasons

  • For Estimation of Final Project Cost
  • To estimate the final project cost from the contract drawings and specification given by the client.
  • Material and labour quotes are obtained from different suppliers and subcontractors respectively for the quantities taken off the contract drawings.

For Budgeting

  • Clients carry out feasibility studies during the preconstruction stage to determine whether they can afford the proposed project.
  • Approximate quantities from initial building sketches can be used for price comparison.
  • Cost Comparison of Different Designs
  • During the design stage, clients can use approximate quantities from the initial drawing sketches to compare different designs and specifications. This can assist their decision-making process.
  • Material Ordering
  • Taking off accurate quantities ensures accuracy when ordering construction materials, thus minimising wastages from over-ordering, under-ordering, and wrong orders.

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Self-assessment Task

  • How would you explain the purpose of taking off quantities to a new colleague? (THREE).
  • In simple terms, define the following terminologies:
  • Quantity take-off
  • (cost) Estimation
  • Bill of quantities
  • (Building) Specification

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  • In simple terms, define the following terminologies in the BOQ you have examined. Also, provide an example for each of the terminologies:
  • Preliminaries
  • Prime cost
  • Provisional sum
  • Attendance (fee)
  • Overheads
  • Contingencies

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Bibliography

Pearson (2017) BTEC national construction student book. London: Pearson.

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