Approximate bill of quantities
An approximate bill of quantities (sometimes referred to as a notional bill of quantities or provisional bill of quantities) can be used on projects where it is not possible to prepare a firm bill of quantities at the time of tendering.
Generally, the design will be relatively complete, but there is either insufficient time or information to determine the exact quantities and so a conventional bill of quantities cannot be prepared.
Tendering on the basis of an approximate bill of quantities can allow early selection of the contractor and so an early start on site. However, the approximate nature of the bill of quantities will tend to result in more variations during construction and so less price certainty when the investment decision is made. This means that even if it is not possible to determine exact quantities, it is sensible to try to ensure quantities are as accurate as possible.
Some contracts allow for re-measurement of approximate quantities (for example, this is common on cut-and-fill on roadworks). Here, quantities are simply revised and payments made accordingly without the need to instruct a variation.
If an approximate quantity turns out not to have been a realistic estimate of the quantity actually required, this may constitute a relevant event, giving rise to claims for an extension of time and loss and expense.
Approximate bills of quantities can also be used during the design process as a tool for controlling design costs (see approximate quantities cost plan below). They are then sometimes included in the tender documents as a guide with a caveat stating that responsibility for measuring quantities lies with the contractor, and drawings and specifications take priority over any description in the approximate bills.
An approximate quantities cost plan is, in effect, a priced approximate bill of quantities. It is a development of the elemental cost plan, but 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.
It presents a more accurate picture of 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 as a consequence may be more expensive. The approximate quantities cost plan should form a solid base for an effective value engineering exercise. From the point that the approximate quantities cost plan has been approved, cost control can be introduced by treating changes as if they are variations.
[edit] Related articles on Designing Buildings Wiki
- Advantages of a bill of quantities.
- Approximate bill of quantities vs approximate quantities cost plan.
- Approximate quantities cost plan.
- Bill of quantities.
- CAWS.
- Common mistakes in bill of quantities.
- Extension of time.
- Firm bill of quantities.
- Loss and expense.
- New Rules of Measurement.
- Packaging.
- Provisional sum.
- Relevant event.
- Standard Method of Measurement (SMM7).
- Types of bill of quantities.
- Unpriced bill.
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.