A bill of quantities materials is a document containing the specifications and quantities required for construction work. It is usually prepared using a standard methodology, such as SMM7 or the New Rules of Measurement.
This allows contractors to price the work accurately and compare their proposals against other bids. It also helps to ensure that all parties are following the same standards.
Definition
A bill of quantities (BoQ) is a document that provides a detailed list of the materials, labor, and equipment required for a construction project, along with their estimated costs. It is generally prepared by a cost consultant (such as a quantity surveyor) after the design has been completed and the specifications have been finalized. The quantities listed in a BoQ may be measured in terms of number, length, area, volume, or weight. It also includes any applicable taxes or contingencies.
A BoQ is often issued to tenderers as part of the tender documentation, which is used by suppliers to prepare their prices for carrying out the construction work. The BoQ is usually split into different work sections, based on likely sub-contract packages, to make it easier for tenderers to compare pricing. It should also include a contingency sum, which refers to unforeseeable costs that are expected to be incurred during the construction process.
Using a BoQ helps to ensure that all contractors are bidding on the same work and that the price is fair. It can also help to streamline project billing by making it easier to compare contractor invoices. On larger construction projects, a BoQ is typically prepared by a quantity surveyor or civil engineer who specializes in preparing these documents. For smaller projects, it may be possible to use a computer software program that can help with the preparation of a BoQ.
Purpose
Bills of quantities play a vital role in construction projects, helping to facilitate project planning, cost estimation, and procurement. They also help to ensure that construction activities are completed on time and within budget. Creating a BOQ involves gathering all relevant project documents, including architectural and engineering drawings, specifications, and preliminary material lists. Then, the project is broken down into manageable phases or stages based on construction timelines, work areas, and systems involved (e.g. excavation, concrete works, electrical installation, plumbing). Then, the required materials are identified based on the project documentation and collated into a list that includes an item description, unit of measurement, quantity, and rate.
Contractors can then use this information to prepare their tender proposals. This makes it easier to compare quotes and select the most competitive bids. It also helps to prevent misunderstandings and disputes, as contractors will have access to the same data when pricing their proposals.
Another benefit of preparing a BOM is that it allows for accurate task sequencing. This ensures that the correct materials are in place at the right time, avoiding costly delays and minimizing downtime. It also assists with inventory management, production control, and supplier coordination. For example, a bicycle manufacturer might create a BOM that lists all the necessary components needed to build a bicycle, including seats, frames, brakes, handlebars, chains, tires, wheels, cranksets, and pedals.
Types
A bill of quantities (BoQ) provides a detailed list of materials and their estimated costs for a construction project. It is used as the basis for procurement and pricing, and helps track and monitor the progress of a construction project. BoQs are typically prepared in accordance with a standard methodology, which reduces the likelihood of misunderstanding and disputes between tenderers.
There are different types of BoQs, including elemental, trade, activity, operational, annotated, and provisional bills. An elemental BoQ breaks down the work into its elemental components and estimates the quantities required for each component. This type of BoQ is commonly used in engineering projects, where it allows a more accurate comparison of prices and scopes of work among competing bidders.
An approximate or notional BoQ is often used on projects where the design isn’t complete enough to enable a QS to prepare a firm Bill of Quantities at the time of tendering. It is also often used on projects where the construction schedule has a limited window for completion. However, an approximate BoQ can increase the amount of variation during construction, which may result in less price certainty when the investment decision is made.
A detailed and accurate BoQ is crucial to ensuring a successful construction project. In addition to providing an estimate of materials and their cost, a BoQ can also help manage and control project budgets and ensure that all project requirements are met. For example, a BOM can organize materials by stage, allowing the project manager to easily see which materials are needed for each phase of the construction process. This can also help organize deliveries and simplify on-site management.
Examples
Depending on the project and the type of work being undertaken, bills of quantities can be presented in various formats. Typically, they are arranged in a hierarchical format to illustrate the linkages between individual components or assemblies. For example, a computer may be broken down into its components such as processors, hard drives, RAM panels and so on. Alternatively, the information can also be exploded in an implosion display that displays each component as an assembly or individual item.
Once the bills of quantities are prepared, the cost surveyor or QS calculates rates for each item in accordance with a predetermined set of standard methodologies. This helps to avoid ambiguity and confusion. It also helps to prevent disputes from arising due to different interpretations of pricing and quantities. In the UK, for example, bills of quantities for general construction works are usually prepared in accordance with the Standard Method of Measurement 7th Edition (SMM7), which was functional until 1 July 2013. It was then replaced by a new standard known as the New Rules of Measurement.
Once the rates are determined, the QS then translates these into an estimate of the total construction cost. This estimate can then be used as a basis for tendering. In addition, the QS can provide it to contractors to make sure that their pricing is consistent with the design and specifications of the project.