Construction Quantity Surveying
Construction Quantity Surveying
2 Measurement and Quantities
2.1 Measurement guides and coverage rules
Measurement of construction work is at the core of quantity surveying and has long been the basis of construction tendering systems. The traditional document used to show this information is a trade bill of quantities (BOQ) prepared by a PQS for a client. If a client wishes to include a BOQ as a tender document in order to obtain a lump sum price for a construction project, the BOQ and stated quantities will become binding on the contractor and client if included in a contract. After becoming a contractual document, the quantities stated take priority, and it is only possible to adjust them with a variation authorised either by the client's agent or another authorised title named in the contract.
In general, a BOQ is a document formatted and worded in accordance with a set of coverage rules provided from a measurement guide, which comprises a measured quantity alongside a description of the works. This permits the -contractor's estimator to understand the requirement and apply a rate to a given quantity that includes labour, plant and materials in order to determine a price. When preparing this type of bill, the design detail and specification need to be sufficient for tendering purposes and represent the detailed final information. This is because the objective of a BOQ is for competing contractors to provide a fixed lump sum price based upon firm quantities on a completed design. If a client wishes an early start on a project with the design part complete, a bill of approximate quantities can be prepared in lieu. Here, quantities are measured from the design and documentation available, and contractors apply rates to permit the works to commence at an agreed price. Subsequently, the actual installed quantities are remeasured by the contractor's quantity surveyor and valued in accordance with the rates provided.
Clients may decide not to include a BOQ as a tender document because of the alternative procurement routes available, which make it possible to transfer risk for quantities to main contractors. Main contractors, and in turn subcontractors, have adopted the term BOQ generically to refer to a measured schedule of works prepared by the parties responsible for measurement. However, the use of the traditional BOQ as a tender and contractual document refuses to become -obsolete, and many contractors and PQS practices recognise the advantages it provides:
It forms an integral and valuable source of reference for a tender, reducing contractors' tendering costs, and leading to more competition between contractors, which benefits the client
A competitive market is created as contractors and subcontractors are more willing to price work from scheduled quantities rather than prepare measures themselves
Negotiation periods following receipt of tenders are rapid with a quick start on site due to the scope identified in the bills
It assists contract administration to identify and value the works in progress
Rates in the bills are used as a basis for pricing variations
It assists with the preparation of a final account as it sets the basis of the contract sum.
The format of a BOQ must follow industrial standards and be consistent, as the bill will pass through the hands of many individuals during the tender period and construction phase. For this reason, a standard format and common understanding of phraseology with descriptions are required. To satisfy this, the industry adopts standard guides defining rules of measurement and descriptions so that the final document is recognisable with concise terminology. There are a number of standard industrial guides available that provide coverage rules to prepare BOQ/measured schedules.
Standard Method of Measurement of Building Wo