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procurement guide - specification and drawings


A contractor is selected and appointed on the basis of a lump sum bid provided in response to a detailed Specification document, which when read in conjunction with the drawings, defines the scope of work to be carried out as the contract works.

The Specification can also include provisional allowances for unforeseen or undesigned work; and also allowances can be included for specialist works yet to be tendered. Measurements and quantities are prepared by the tenderers to enable them to price the work. Like Schedules of Work, the use and meaning of these provisional sums needs to be described and defined in the documents.
Normally, tendering is in competition with a pre-selected list of approximately five contractors.


  • The lump sum price is firm, subject only to variations which may be instructed during the course of the contract works.
  • Client risk tends to be avoided because the contractor prepares his own measurements and quantities.
  • Can incorporate Design and Build and Performance Specified works if required.


  • The design must be well advanced in order to prepare the detailed Specification documents. This procurement route can therefore mean a later site start than with alternative procurement routes.
  • Give less control of cost when variations are instructed than firm Bills of quantities because of the lack of a defined system of measurement of the building elements.
  • Tenders are not as easily comparable to each other as is possible with Bills of Quantities, because the tendering contractors may interpret and price risk in the Specification document in different ways.


Specification and Drawings are Appropriate to smaller projects such as house extensions and renovations; partly because all tenderers need to produce their own quantities and partly because of the time involved in achieving a sufficiency of the designs to enable the Specification tender documents to be prepared.

Like Schedules of Work, the use this form of procurement is not particularly appropriate where it is likely that change will be required by the client after the contract has been started.

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