Preparing a bill of quantities is an essential task for construction projects. It allows building contractors to bid on a fair and accurate basis. It is a standardised document prepared by the Quantity Surveyor (Employer’s Consultant) with construction information provided by the design team.
It is then used throughout the project, especially during contractor selection and during the tendering process. It is also useful in creating payment applications and for scoping progress.
Breaking Down the Work
Quantity surveyors, architects and engineers use a Bill of Quantities (BoQ) to help with construction project planning, cost estimating, contractor pricing and material ordering. A BoQ contains precise breakdowns of all the parts, labour and materials required for a particular piece of work and is often based on standard work breakdown structures, such as the CSI MasterFormat and Common Arrangement of Works Sections (CAWS).
It requires obtaining the design team’s drawings and specifications along with the contract type to be used. A Quantity Surveyor or Cost Consultant typically prepares the BoQ during the pre-construction phase of a project.
There are two distinguishable types of BoQs, namely, a firm and approximate BoQ. A firm BoQ involves measuring and describing the work in detail, allowing tenderers to price it accurately. The approximate BoQ is prepared when the amount of information available for a project is not sufficient to enable the QS to prepare a firm BoQ.
A BoQ has many benefits, including facilitating a competitive tendering process, enhancing the understanding of construction project requirements among clients and contractors, ensuring transparency, providing cost certainty, and facilitating effective project control. However, whether a BoQ or Schedule of Works (SoW) is more suitable for a project depends on multiple factors, including the scope and complexity of the work and the client’s preferences and requirements.
Preparing a Bill of Quantities
A BOQ is an estimate of all materials, labour and equipment that will be needed for a construction project. It is usually created by a quantity surveyor. The BOQ must be prepared according to a standard methodology. Otherwise, the chances of making mistakes increase substantially. These errors include incorrect measurement of quantities, arithmetic errors, errors due to various changes made during the construction process, omissions, miscounting or counting the same item twice, and ignoring changes in currencies or units of measure.
A good way to prepare a bill of quantities is to start by listing the building materials and their respective unit prices. This is typically done by reviewing the plans and specifications. You should also identify the unit of measurement used for each article. For instance, concrete is usually measured in cubic meters. After you have completed this step, you should compare your list with the architect’s plan to make sure that you have included all the items necessary for the project.
Then, you should add the labor and overhead costs to the total cost of the materials. You should then divide the total cost of the materials by the number of items to determine the price per article. Finally, you should include a contingency sum for any unforeseeable expenses that are likely to be incurred during the project.
Pricing the Work
Using a Bill of Quantities helps the construction project owner save time in the tendering process, as all contractors use one document to prepare their bids. The tendering committee can easily compare different contractors’ proposals and select the best contractor. It also improves the quality of the proposal as it is based on proper mathematical calculation instead of guesswork.
The contractor then prices each item of work on the basis of the drawing and specification details that have been provided. A percentage for overheads and profit is also added to the rate for each item. Items of work that may require a specialist to carry out are usually priced at higher rates. The total cost for materials, equipment, and labor is then added together to arrive at the final estimate.
It is important that the BoQ be developed according to a standard methodology so that ambiguities and misunderstandings can be avoided. In the UK, for example, bills of quantities were until recently prepared following the Standard Method of Measurement 7th Edition (SMM7). This was functional until 1st July 2013 when it was replaced with a new standard known as the New Rules of Measurement. The use of these standard methodologies makes the preparation of a Bill of Quantities much easier and more accurate, and it also helps to avoid disputes that may arise as a result of different interpretations of pricing and quantities.
Finalizing the Bill of Quantities
Preparing a bill of quantities is a time-consuming process that requires careful attention to detail. However, it is essential to the success of a construction project. It provides a clear and detailed picture of the requirements for the project and allows contractors to submit competitive tenders.
A BoQ is usually prepared by a quantity surveyor using information from the design team’s drawings and specifications. It includes a description of the work to be carried out, together with quantities and unit prices. The quantities are usually measured in accordance with a standard measurement methodology, such as the New Rules of Measurement (NRM), which replaced SMM7 on 1 January 2013.
Bills of Quantities can be prepared at any stage during the design phase. However, it is most efficient to prepare them when the project design is nearing completion. This will ensure that the quantity surveyor can measure the completed designs accurately and avoid costly change orders during the construction process.
There are several different types of BoQs, depending on the size and complexity of a project. An itemized BoQ lists all the materials, labor, and equipment required for a project, including their unit prices. An abstract BoQ summarizes the information in an easy-to-read format, while a trade BoQ is organized by construction elements, such as concrete, steelwork, or carpentry.