Quantity
Contents |
[edit] Introduction
Quantity in a general sense is the amount of something that there is, was or will be. This amount may be measured in terms of number, weight, length, area, volume and time. For example, there were 50 accidents last year, or 2kg of flour will be required to make the cake. The same general sense may be applied to construction: the estate when completed will comprise 250 dwellings housing a maximum of 1,000 people.
[edit] Bill of quantities
In a more specialised construction sense, ‘quantity’ or ‘quantities’ can refer to the ‘measured’ (i.e calculated or estimated) amounts that are contained in a bill of quantities.
A bill of quantities is a document prepared by the cost consultant (often a quantity surveyor) that provides project-specific, measured quantities of the items of work required to complete the project. These quantities are usually highlighted in the drawings and specifications that form part of the tender documentation.
Preparing a bill of quantities requires that the design is complete and a specification has been prepared. The bill of quantities is issued to tenderers to enable them to prepare a price for carrying out the works. The bill of quantities assists tenderers in the calculation of construction costs for their tender, and, as it means all tendering contractors will be pricing the same quantities (rather than taking off quantities from the drawings and specifications themselves), it also provides a fair and accurate system for tendering.
However, it is usually the case that during the construction period, the quantity surveyor prepares different forms of quantities by measuring and valuing the work carried out at regular intervals. These new quantities allow the client to accurately and fairly pay the contractor for the work completed.
For more information see: Bill of quantities.
[edit] Standard methods of measurement
In order to ensure cross-industry harmonisation, it is important that the way building quantities are measured is conducted on a consistent basis and allows the costs of different projects to be compared meaningfully. To achieve this, quantity surveyors can use standard ways to measure quantities. This includes the Standard Method of Measurement (SMM7) or New Rules of Measurement (NRM 2) and Agreed Rules of Measurement 4.
For more information see: SMM7 and NRM.
[edit] Approximate quantities.
A development of the elemental cost plan of estimating construction project costs, approximate quantities form part of an approximate quantities cost plan which represents a first attempt to measure defined quantities from drawings (or to ‘take them off’)
An approximate quantities cost plan is part of the iterative cost planning process and is a development of the elemental cost plan. Unlike the elemental cost plan (in which the cost of elements is broken down from the overall construction cost, based on the experience of the cost consultant and known costs of similar completed projects), the approximate quantities cost plan is a first attempt to measure defined quantities from drawings. In effect, it is a costed approximate bill of quantities.
For more information see: Approximate quantities.
[edit] Related articles on Designing Buildings
Featured articles and news
ECA Industry Awards 2024 shortlist revealed
22 leading businesses from across the electrotechnical and engineering services sector.
Government unveils Skills England strategy
Skills England to transform opportunities and drive growth.
New Government Hub for York Given Planning Green Light
For up to 2,600 civil servants, due for completion by 2028.
Construction Skills Certification Scheme cards
July update on Professionally Qualified and Academically Qualified Person Cards.
BSRIA Briefing 2024, November 22
Sustainable Futures: Redefining Retrofit for Net Zero Living.
The CLC on driving competency in the retrofit sector
Previously published roadmap on skills for net zero.
The first labour government King's speech in fifteen years
Construction industry reactions, support and some concern.
CIOB Retrofit of Buildings Technical Information Sheet
What retrofit is, the approach to be taken and processes to be followed.
Adapting Historic Buildings for Energy and Carbon Efficiency
Historic England advice note 18, free download published.
10 retrofit projects revisited 10 years after completion.
Information orders, building liability orders and SPVs
Key BSA terms and how they impact special purpose vehicles.
Listed despite problems with its design.
Zen and the art of cycling exploration.
Design Council Homes Taskforce launched
To support government 1.5 million homes target within UK climate commitments.