6 Main Types of Bills of Quantities
A bill of quantities is a document that is prepared by the client’s quantity surveyor as a basis for estimating the cost of a construction project. It contains a list of all the work items and detailed descriptions that form part of the scope of work for the project.
Different formats are adopted by different quantity surveyors depending on their needs and the context of their work. These have led to the various types of bills of quantities being born. In this article, we will discuss six main types of bills of quantities as follows:
1. Elemental Bills of Quantities
This type of bill of quantities is divided into appropriate building elements. In each element, work is either billed in order of work sections or grouped in the appropriate building sequence.
The building sequence represents the actual order of the construction activities as they would be carried out on site. For example, construction of walls coming before plastering and painting.
A building element is a part of a building that fulfils specific functions irrespective of its design, specification and construction.
As a building element, external walls provide the external vertical envelope to a building, separating the external and internal environment irrespective of how it may be constructed.
2. Trade Bills
In this type, the various work sections to be carried out by given trades are identified and items in a bill of quantities grouped into the appropriate work sections. These may include sections like “Excavation and Filling”, “Brick or Block Walling”, among others.
The bill is arranged in trades; with each trade subdivided into functional elements. The items within each trade are arranged in the normal trade order within the sections.
A trade is a job requiring manual skills and specialized training. Therefore, construction trades can be understood to mean construction works that require some specialized skills and manual labour for execution.
3. Operational Bills
This is derived from operations; which can be defined as the work done by a man at some definite stage in the building process.
The bill of quantities involved dividing work into site operations. Labour and plant requirements are described in terms of operations required, together with a schedule of materials for each operation.
4. Activity Bills of Quantities
This is a further development and refinement of the operational bill of quantities format. Whereas labour and plant requirements were separated from a schedule of materials in the operational format, the activity bills of quantities don’t separate them.
The bill is divided into sections based on activities or operations derived from network analysis. This simply means the sequencing of activities based on which has to be done first for the other to start.
Some activities need to be completed first before others could be started. A good example is “excavation of foundation trenches” to be completed before “blinding of surfaces” and subsequent “foundation footing construction”.
5. Annotated Bills
In some cases, work measured and described in a bill of quantities may not be directly identifiable from drawings. This led to the development of a practice of annotating such works with notes giving their location.
When a bill of quantities is prepared that way, it is called an annotated bill of quantities.
6. Provisional Bills of Quantities
As the name suggests, this type of bill of quantities contains provisional or approximate quantities. It is issued to tenderers on the basis that the quantities will be remeasured during the construction phase of the project where they differ from the actual or as-built quantities.
It is normally used where drawings and the building specifications cannot be finalized before selecting a contractor. The advantage of this bill is that it reduces the tender documentation period and allows the contractor to commence work earlier.
As identified above; elemental, trade, activity, operational, annotated and provisional bills are the main types of bills of quantities. Other types have not been covered but you are free to include them in the comments section below.
If you plan to build, it is good to engage a quantity surveyor to advise you on the financial matters of the construction project. Don’t just invest money without a good plan. A list of registered professional quantity surveyors in Kenya can be found on the official website of the Board of Registration of Architects and Quantity Surveyors.