A bill of quantities BoQ describes and measures the work required for a construction project. Contractors use the listed quantities to price the work, prepare tenders and provide a detailed breakdown of their proposed charges.
For construction teams, understanding a BoQ helps clarify the scope before work begins. During delivery, the document can also support valuations, variations and financial control, depending on the contract.
What Is a Bill of Quantities?
A bill of quantities lists construction work into individual items, each with a description, unit of measurement and quantity. The information comes from project drawings, specifications and other design documents.
Contractors add unit rates and calculate totals to produce a priced BoQ. Giving tenderers the same measured information creates a consistent basis for comparing their prices.
For example, a flooring item might specify 200 square metres of a particular floor finish. Each contractor prices that defined work rather than making separate assumptions about its quantity and specification.
RICS identifies tender preparation as a central purpose of a BoQ. When the document forms part of the contract, it also provides a basis for valuing completed work and variations.
What Does a Bill of Quantities Include?
A bill of quantities describes the work required and provides measured quantities for contractors to price. It typically covers:
- Materials: The types, specifications and quality of materials required.
- Labour: The work needed to complete each item, with labour costs usually included in the item rate.
- Plant and equipment: Machinery, tools and temporary equipment needed to carry out the work.
- Work descriptions: Clear details of what each item includes so contractors understand what to price.
- Quantities and units: Measured amounts expressed in metres, square metres, cubic metres, number or other suitable units.
- Rates and totals: Spaces for contractors to enter unit prices and calculate the amount for each item.
- Preliminaries: Site running requirements, including supervision, welfare facilities, security and temporary services.
- Provisional sums: Allowances for work that cannot be fully defined at the tender stage.
Why Is a Bill of Quantities Important?
A BoQ gives contractors and clients a shared description of the work they are pricing. Clear descriptions and measured quantities reduce uncertainty about what each tender includes.
Without a common pricing document, contractors may measure the same design differently or allow for different items. Those differences can make quotations difficult to compare.
The document also creates a detailed reference for commercial discussions. Teams can identify the relevant work item, examine its quantity and review the submitted rate.
Accuracy matters throughout. Missing work, unclear descriptions or outdated drawings can weaken the pricing exercise. A detailed BoQ helps teams identify gaps, but the document still depends on reliable design information and careful checking.
Benefits of Using a BoQ During Construction:
During construction, a BoQ gives contractors and commercial teams an organised reference for reviewing work, assessing changes and supporting payment discussions.
Clearer Work Package Reviews
Site managers and quantity surveyors can use identified items when scoping a work package. Specific descriptions help teams explain what the priced work covers and investigate possible omissions.
More Structured Valuations
Where the contract incorporates the priced BoQ, it helps the commercial team value completed work. Item references and rates then provide the basis for interim valuations.
A Reference for Variations
When the scope changes, teams can use BoQ descriptions and rates to assess the variation. The contract determines whether an existing rate applies or a different valuation approach is necessary.
Easier Commercial Handover
Estimators can use the priced breakdown to explain tender assumptions to the delivery team. That handover helps project managers and buyers understand the scope behind the figures before placing orders.
Better Records for Future Estimates
After completion, contractors can compare tender assumptions with project outcomes. Reviewing quantities, purchasing costs, and labour performance helps improve the information available for future pricing.
The value during delivery comes from using the BoQ alongside current project records and the applicable contract terms.
How Does a BoQ Support Budgeting and Cost Control?
A priced BoQ provides a starting point for organising project finances. Contractors use this information to control costs by setting internal budgets, recording expenditure and reviewing the remaining work.
1. Review the Priced Scope
Start by checking the tendered quantities, rates, allowances and exclusions. Confirm which drawings and specifications support the pricing.
The delivery team should understand the assumptions behind major work packages, including any unresolved scope or provisional work.
2. Establish Internal Cost Budgets
Use the priced work breakdown to help organise budgets for materials, labour, plant and subcontractors.
The tender price and the contractor’s expected delivery cost serve different purposes. Tender rates may include overheads and profit, so the commercial team should establish internal cost allowances before measuring spending against them.
For example, a contractor might price a flooring package at £13,000 and set an internal delivery budget of £10,000 based on expected purchasing and installation costs.
3. Allocate Costs to Work Packages
Create cost codes that reflect how the team will manage and report the work. Assign purchase orders, supplier invoices, labour and other expenses to those codes.
A consistent structure makes it easier to compare the flooring budget with the costs of delivering that package.
4. Include Outstanding Commitments
Recorded invoices show only part of the financial position. Approved orders may commit the contractor to costs before suppliers submit their invoices.
Review actual expenditure together with outstanding commitments. When an invoice replaces part of an order commitment, update the remaining commitment so the same cost does not appear twice.
5. Assess the Cost of Remaining Work
Compare the available budget with the work still required.
Suppose the flooring package has a £10,000 budget, £6,000 in actual costs and £2,000 in outstanding commitments. The team has a £2,000 unallocated budget. If additional work outside those commitments will cost £3,000, the package faces a forecast overrun of £1,000.
That review gives the contractor time to investigate the cause and consider practical changes.
6. Record Changes and Update Forecasts
Maintain a clear record of variations, revised quantities and approved budget changes. Keep expected client recovery separate from the cost of additional work.
Regular reviews should explain what changed, how the change affects the remaining budget and what the project is now expected to cost.
How Can Construction Cost Control Software Help?
Construction cost tracking and budgeting software helps contractors spot budget pressure before costs overrun. By bringing purchase orders, invoices and labour costs into one view, teams can see what they have spent, what they have committed and how much budget remains.
LiveCosts brings budgeted, actual and committed costs into one project view. Contractors can link purchasing to the relevant job and cost code, see commitments before invoices arrive and allocate labour costs to the work.
For example, a buyer can check a package’s remaining budget before raising another purchase order. The commercial team can then review the commitment alongside recorded costs to assess budget pressure.
LiveCosts 3-way matches supplier invoices against purchase orders and deliveries before approval. Its reports show budget v actual costs, commitments, CVR, WIP and project profitability. Syncs with Xero, QuickBooks and Sage connect approved financial information with accounting.
Contractors can use the priced BoQ to help set project budgets, then track purchases, invoices and labour costs against those budgets as work progresses.
FAQs
What Is the Difference Between a BoQ and a BOM?
A bill of quantities describes measured construction work for pricing and tender comparison. A bill of materials lists the physical materials and components required.
For example, a BoQ might describe a measured area of completed brickwork. A BOM would identify materials such as bricks, cement and sand. A BOM lists the materials and components required and may also include their prices.
How Is a Bill of Quantities Prepared?
The preparer reviews drawings and specifications, measures the work, writes item descriptions and organises the quantities into sections using the agreed measurement rules. They then add relevant preliminaries, allowances and pricing instructions before checking and issuing the document.
Contractors complete the pricing by adding unit rates and totals.
Who Prepares a Bill of Quantities, and Who Prices It?
A quantity surveyor or cost manager commonly prepares the BoQ for the client. Tendering contractors price the items, often using supplier and subcontractor quotations.
Responsibility varies with procurement. On design and build projects, the main contractor or work package contractors may prepare the quantities.
What Are the Rules of Measurement?
Rules of measurement explain how to measure and describe construction work consistently. They establish conventions for units, item descriptions and the work included within each item.
RICS NRM 2 provides detailed measurement guidance for building works. Applying an agreed method helps tenderers interpret and price quantities on a common basis.
What is the relationship between SMM7 and a BoQ?
SMM7, published in 1988, provided rules for measuring and describing building work when preparing a bill of quantities. SMM7 set the measurement method, while the BoQ recorded the project’s work items and quantities for contractors to price. RICS replaced SMM7 with NRM 2, effective from 1 January 2013.
