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.
The approximate quantities method is regarded as being more accurate and reliable than other estimating methods in showing where costs are distributed. In particular, it draws to the attention of designers those elements of the design that are standard and those that are not and which, as a consequence, may be more expensive.
Unlike the elemental method, the basis of the approximate method of estimating is the grouping together of diverse, combined items under a rate (known as a composite rate) which is calculated by combining the individual prices of the components in the group. Because the items grouped together have the same dimensions (whether in metres or square metres, or perimeter and area), it allows those items to be measured at the same time.
For example, under the approximate quantities method, items such as roofs can be grouped with soffits and ceilings; this would not occur in the elemental plan.
The approximate quantities cost plan can form a solid base for an effective value engineering exercise. However, it should be accompanied by a schedule of assumptions made and perhaps a cash flow projection. A pre-construction whole-life cost plan may also be prepared.
[edit] Related articles on Designing Buildings Wiki
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.