Bills of Quantities and Schedule Preparation

Introduction

A bill of quantities (BoQ) is a structured document that describes, measures and prices the work required for a construction project. It translates drawings, specifications and contractual requirements into a common commercial language for tendering, valuation and cost control. A well-prepared BoQ allows contractors to price the same scope of work, enables the client to compare tenders on a consistent basis, and provides a framework for administering payments and variations after contract award.

Quantity surveying is therefore not limited to taking-off dimensions. It involves interpreting design information, selecting appropriate descriptions, applying measurement rules, coordinating documents, identifying uncertainty and presenting information in a form that is contractually useful. Errors in description, omission of work or inconsistency between the BoQ and drawings can produce disputes, distorted tender prices and unreliable cost forecasts.

This chapter examines the preparation of descriptions, preliminaries, preambles, measured work sections, provisional sums, prime-cost items, dayworks and schedules. It also considers coordination, digital measurement, quality assurance and the professional responsibilities of the quantity surveyor.

Learning Objectives

By the end of this chapter, the learner should be able to:

1. Explain the purpose, structure and contractual uses of a bill of quantities.
2. Distinguish between preliminaries, preambles, measured work, provisional sums, prime-cost items and dayworks.
3. Prepare clear, complete and measurable descriptions for construction work.
4. Organise work into logical sections and prepare coordinated schedules.
5. Apply measurement principles to a small worked example.
6. Evaluate uncertainty, allowances and risks in tender documentation.
7. Use digital tools responsibly while maintaining professional checking and accountability.

1. The Nature and Functions of a Bill of Quantities

A BoQ normally contains item descriptions, units, quantities, rates and amounts. Depending on the procurement system and standard method of measurement, it may also contain information about attendance, taxes, discounts, design responsibility, alternatives and contract particulars.

Its principal functions are:

• Tendering: each tenderer prices an approximately identical scope, improving comparability.
• Contract formation: when incorporated into the contract, the BoQ describes and quantifies obligations.
• Interim valuation: completed quantities and applicable rates support payment certification.
• Variation valuation: existing rates can assist in valuing changes, subject to contract conditions.
• Cost planning: measured quantities and rates provide a basis for elemental and trade analysis.
• Cost control: expenditure can be compared with the original bill and forecast final cost.
• Communication: the document links the client, consultant, contractor, subcontractors and suppliers.

A BoQ is not automatically a complete specification or a substitute for drawings. Its legal effect depends on the contract conditions and the applicable measurement standard. In some contracts quantities are remeasured; in others they are approximate or used mainly for tender comparison. The quantity surveyor must therefore establish the contractual status of the document before preparing it.

1.1 Bills of Quantities and Other Schedules

A full BoQ generally includes measured work, preliminaries, preambles, provisional sums, prime-cost items and sometimes daywork schedules. A schedule of works describes activities without necessarily providing measured quantities. A schedule of rates provides rates for defined work items, often without project-specific quantities. An activity schedule allocates a contract sum to activities and is common in lump-sum or design-and-build contracts.

These documents should not be treated as interchangeable. A schedule of works may be appropriate where design information is incomplete, but it may provide less precise control over measurement and valuation. The selected document should reflect the procurement route, design maturity, risk allocation and contract conditions.

2. Information Required Before Preparation

Preparation begins with an information audit. The quantity surveyor should obtain, register and review:

• architectural, structural and building-services drawings;
• specifications and performance requirements;
• geotechnical and site investigation reports;
• employer’s requirements or contractor’s proposals, where relevant;
• statutory and authority requirements;
• design responsibility matrices;
• programme and phasing information;
• site logistics and access constraints;
• schedules of finishes, doors, windows and equipment;
• environmental, health and safety requirements; and
• the proposed form of contract and method of measurement.

Each document should have an identifiable revision, date and status. A drawing register and query log reduce the risk of measuring superseded information. Where drawings conflict, the discrepancy should be recorded and referred to the design team rather than silently resolved through assumption.

A useful principle is: measure what is defined, identify what is uncertain, and do not conceal missing information in an apparently precise quantity.

3. Measurement Rules and Units

Measurement rules establish what is included in an item, how dimensions are taken, how deductions are treated and which ancillary operations are deemed included. The chosen standard method of measurement may specify rules for excavation, concrete, masonry, finishes, services and external works. Local standards and contract requirements must be followed; terminology and rules vary between jurisdictions.

Common units include:

The unit should express the measurable quantity rather than merely the procurement package. For example, concrete is normally measured by volume, reinforcement by mass or length according to the applicable rules, and formwork by area of contact surface.

For a rectangular element, volume is calculated as:

where V is volume in m³, L is length in metres, B is breadth or width in metres, and H is depth or height in metres. The expression applies when the element is rectangular and dimensions are measured consistently. For irregular shapes, the element should be divided into measurable geometrical parts or measured using the applicable standard rules.

For repeated identical elements:

where n is the number of elements and Q_each is the quantity of one element. The result is valid only if the elements have the same dimensions and specification.

3.1 Taking-Off and Squaring

Taking-off is the process of extracting dimensions from drawings and converting them into measured quantities. A traditional dimension sheet commonly records the timesing factor, dimensions, description and extension. Squaring means multiplying the dimensions to obtain an extended quantity, while abstracting means grouping similar items for transfer into the BoQ.

A disciplined sequence is:

1. Read the specification and drawings together.
2. Establish measurement units and rules.
3. Identify elements and locations.
4. Record dimensions with references to drawing numbers and detail locations.
5. Extend and total the quantities.
6. Check deductions, repetition and interfaces.
7. Abstract similar work into bill items.
8. Cross-check the bill against drawings, schedules and specifications.

A dimension should be traceable. For example, “Ground-floor partition, type P2, grid A–D” is more useful than an unexplained total length.

4. Descriptions and Preambles

4.1 Principles of Good Descriptions

A BoQ description should identify the work sufficiently for a competent contractor to price it without relying on hidden assumptions. It should state, where relevant:

• the material or product;
• grade, strength, class or performance;
• dimensions and thickness;
• location and level;
• method of construction where specified;
• finish, treatment or surface preparation;
• fixing, jointing or support requirements;
• testing, protection and commissioning;
• associated accessories and ancillary work; and
• reference to the relevant specification clause or drawing.

Descriptions should be concise but complete. They should avoid trade slang, unexplained abbreviations and wording that transfers design responsibility unintentionally. “Supply and install” should not be used to imply a design obligation unless the contract clearly requires it.

A weak description might read: “Blockwork to walls.” A stronger description might identify block type, thickness, mortar, location, finish and whether reinforcement or cavity accessories are included. The exact wording depends on the measurement standard and project specification.

4.2 Preambles

Preambles are introductory clauses that explain the measurement and pricing assumptions applying to a section or the whole bill. They may address:

• the measurement standard used;
• interpretation of dimensions and quantities;
• inclusions in rates;
• contractor’s obligations for waste, laps and cutting;
• protection, temporary support and making good;
• testing, samples and approvals;
• coordination with other trades;
• access, working space and sequencing; and
• treatment of risks, exclusions and provisional work.

Preambles must be coordinated with the contract conditions and specification. They should not be used to create contradictory obligations or to hide significant work in a general statement. If an operation is important to price comparison, it is often preferable to identify it as a separate item.

5. Preliminaries

Preliminaries are costs and obligations associated with managing, administering and executing the project but not normally incorporated into a permanent measured element. They can be divided into general and project-specific requirements.

Typical general preliminaries include:

• mobilisation and demobilisation;
• site establishment, offices, stores and welfare facilities;
• temporary services and security;
• supervision and management;
• health, safety and environmental controls;
• insurance, bonds and warranties;
• scaffolding or access systems where not included elsewhere;
• setting out and surveying;
• quality assurance and records;
• protection of completed work;
• cleaning, testing, commissioning and handover; and
• removal of temporary works and reinstatement.

Preliminaries may be priced as a lump sum, as time-related items, or through a combination. A mobilisation cost is often largely time-independent, whereas site supervision and temporary facilities may vary with the construction period. Separating these categories improves transparency and assists valuation when the programme changes.

The quantity surveyor should avoid double counting. For example, if scaffolding is measured within a façade work section, it should not also be included in general preliminaries unless the two items clearly represent different obligations.

6. Organising Measured Work Sections

Measured work should be arranged in a logical sequence based on the selected measurement standard, construction process or trade structure. A typical building bill may contain:

1. excavation and earthwork;
2. concrete work;
3. reinforcement;
4. formwork;
5. masonry;
6. structural and miscellaneous metalwork;
7. carpentry and joinery;
8. roofing and waterproofing;
9. doors, windows and finishes;
10. fittings and equipment;
11. mechanical services;
12. electrical services;
13. external works and landscaping; and
14. completion and handover requirements.

The order should help a tenderer understand the project and should align with drawings, specifications and the likely sequence of valuation. Section titles, item numbering and page references should remain stable during tendering, with revisions clearly identified.

6.1 Example of a Measured Section

The following abbreviated example is illustrative:

Descriptions should be checked against structural drawings. In particular, concrete strength, reinforcement grade, cover, excavation conditions and disposal requirements should not be assumed from generic practice.

7. Provisional Sums

A provisional sum is an allowance included in the contract for work or expenditure that cannot be sufficiently defined or measured at tender stage. It is not a substitute for design development. The contract should state whether the sum is defined or undefined, or use the terminology required by the governing contract.

A defined provisional sum generally includes enough information about the nature, scope and location of the work for the contractor to make reasonable allowance for planning and execution. An undefined provisional sum is less clearly described and transfers more uncertainty into the contract.

Examples include:

• work pending completion of specialist design;
• excavation in uncertain ground conditions;
• connection charges not yet confirmed;
• alterations to existing services;
• specialist installations awaiting final selection.

When the work is later instructed, the provisional sum is adjusted in accordance with the contract. The adjustment may include the actual cost, contractor’s overheads and profit, attendance and changes in quantities. The precise method is contract-specific.

Provisional sums affect tender comparability because contractors may apply different assumptions to associated attendance, programme and risk. The bill should therefore describe the allowance, state exclusions and identify whether attendance is included elsewhere.

8. Prime-Cost Items

A prime-cost (PC) item is an allowance for the supply of a specified class of goods or materials that has not been finally selected or priced at tender stage. Typical examples are sanitary fittings, ironmongery, appliances, tiles or light fittings.

A PC item normally covers the supply cost of the item. Installation, fixing, delivery, unloading, storage, testing and contractor’s attendance should be measured or described separately unless the contract expressly states otherwise. The contractor’s tender may include an agreed percentage for overheads and profit applied to the difference between the allowance and actual cost.

For example, a bill may state:

The quantity surveyor should avoid using a PC item where the product can reasonably be selected and described before tender. Excessive PC items reduce price certainty and may encourage later cost escalation.

9. Dayworks

Dayworks provide a method of valuing work that cannot reasonably be measured or priced in advance, often because it is urgent, irregular or dependent on unforeseeable site conditions. A daywork schedule may include:

• labour categories and hourly rates;
• plant and equipment rates;
• material cost basis;
• percentage additions for overheads and profit;
• supervision and attendance; and
• records and authorisation procedures.

Daywork is not a general licence to perform poorly defined work. The contract should require written instruction, daily records, labour names or categories, hours worked, plant identification, material invoices and confirmation by the authorised representative.

For a labour component, the basic valuation may be expressed as:

where C is the labour cost, h_i is the recorded number of hours in labour category i, and r_i is the applicable hourly rate. If a contract applies an overhead and profit percentage p, expressed as a decimal, the adjusted amount is:

These expressions assume that the rates and percentage are contractually defined and that hours are properly authorised. They do not determine entitlement by themselves.

10. Schedules Supporting the Bill

Schedules make repetitive or coordinated information easier to read and check. Common schedules include:

• door and window schedules;
• finishes schedules;
• sanitary and plumbing fixture schedules;
• equipment schedules;
• ironmongery schedules;
• room data sheets;
• drawing and document registers;
• provisional-sum schedules; and
• daywork schedules.

A schedule should use consistent identifiers. If a door schedule labels an opening D-14, that identifier should appear on plans, elevations, specifications and the BoQ. A schedule should also identify revision status and avoid conflicting descriptions.

10.1 Schedule Preparation Procedure

1. Establish the information source and responsible designer.
2. Create a unique code for each type or item.
3. Record dimensions, materials, performance and location.
4. Reconcile totals with drawings and room data.
5. Link schedule codes to BoQ descriptions.
6. Check interfaces with adjacent work and services.
7. Issue the schedule with revision control.

Schedules are particularly valuable in buildings with many repeated components. They reduce repetitive descriptions, but they do not remove the need to state clearly what is included in the price.

11. Coordination and Quality Assurance

Coordination is both a technical and managerial activity. The BoQ should be checked against the design using several complementary methods.

11.1 Completeness Review

The reviewer should ask:

• Is every drawing element represented?
• Are temporary and permanent works distinguished?
• Are testing, commissioning and handover included?
• Are interfaces between trades covered?
• Are access, supports, builders’ work and making good allocated?
• Are provisional and PC items justified?

11.2 Consistency Review

Descriptions, units, quantities and specification clauses should agree. Common errors include measuring a wall to one drawing dimension while pricing a different thickness, using inconsistent units, omitting openings, or including the same item in both preliminaries and measured work.

11.3 Arithmetic and Independent Checks

A second person or independent process should review key quantities. Digital measurement software can total areas and volumes efficiently, but it cannot reliably determine design intent, construction sequence or contractual inclusion. High-risk items such as excavation, structural concrete, reinforcement, façade systems and services should receive enhanced checking.

11.4 Tender Query Management

Tenderers should submit queries through a controlled process. Answers that alter scope should be issued to all tenderers through an addendum, not privately to one contractor. This supports fairness and preserves a common tender basis.

12. Worked Example: Quantifying a Foundation Element

Consider an illustrative strip foundation layout with four straight runs. The dimensions are:

• two runs: 12.0 m long;
• two runs: 8.0 m long;
• foundation width: 0.80 m;
• concrete depth: 0.25 m.

The total foundation length is:

The concrete volume is:

Thus, the measured item may be written as 8.00 m³ of reinforced concrete strip foundation, subject to the specified strength, reinforcement and measurement rules. If a 50 mm blinding layer is placed beneath the same foundation, its volume is:

The two volumes must not be combined because they represent different materials and specifications. The example assumes straight, rectangular runs and does not address laps, working space, excavation side slopes, reinforcement or deductions. Those matters require separate measurement.

13. Applied Case: Community Health Centre Tender

Background

The following is an illustrative case. A two-storey community health centre is being procured through competitive tender. Architectural drawings are substantially complete, but the external medical-gas installation and final kitchen equipment selections remain unresolved.

Problem

An initial draft bill contains broad items such as “mechanical services complete,” “kitchen equipment allowance” and “site establishment.” Tenderers interpret these differently. One contractor includes extensive testing and commissioning; another excludes it. The client receives tender totals that differ substantially, but the differences cannot be explained from the bill.

Analysis

The quantity surveyor performs an information and scope review. The analysis identifies four causes:

1. mechanical work is not divided into identifiable systems;
2. installation associated with equipment allowances is not stated;
3. preliminaries combine fixed mobilisation costs with time-related management;
4. unresolved medical-gas design is represented by an unexplained lump sum.

Approach and Solution

The bill is reorganised into measured sections for water, drainage, ventilation, air-conditioning and medical gases. Equipment is listed in a schedule with codes and locations. A PC item is used for selected kitchen appliances, while electrical and plumbing connections are measured separately. The medical-gas work is described as a defined provisional sum, including known locations, performance requirements and testing assumptions. Preliminaries are divided into fixed, time-related and completion items.

A pre-tender review checks every item against drawings and specifications. The client issues an addendum clarifying the scope and requires all tenderers to acknowledge it. A daywork schedule is added for unforeseen service diversions, with written authorisation and daily records required.

Outcome

Tender returns become more comparable. The client can identify the cost of unresolved design separately from the cost of defined work. During construction, the medical-gas provisional sum is replaced by a specialist subcontract package and the adjustment is valued using the contract rules. The equipment schedule supports procurement and avoids confusion about whether installation is included.

Learning Points

The case demonstrates that a BoQ is a coordination instrument as well as a measurement document. Clear allocation of supply, installation, attendance and risk is more valuable than a superficially precise but ambiguous quantity. It also shows why uncertainty should be disclosed through controlled allowances rather than hidden in vague descriptions.

14. Technology, BIM and Artificial Intelligence

Digital measurement platforms and building information modelling (BIM) can link quantities to model objects, specifications and locations. Benefits include faster revision, visual checking, automated schedules and improved change tracking. However, model-based quantities are only as reliable as the model’s geometry, classification, information requirements and revision control.

Artificial intelligence may assist with drawing recognition, classification, anomaly detection and comparison of revisions. It should be treated as an aid rather than an autonomous measurement authority. Professional review remains necessary because software may misread overlapping elements, omit hidden work, confuse design options or infer specifications that are not contractually stated.

Good governance requires:

• a controlled source of truth;
• traceable model and drawing revisions;
• documented measurement rules;
• validation samples and independent checks;
• protection of confidential project information; and
• clear accountability for issued quantities.

15. Challenges, Limitations and Professional Responsibilities

The principal challenges in BoQ preparation are incomplete design, inconsistent documentation, changing client requirements, uncertain ground conditions, specialist interfaces and time pressure. Measurement also involves professional judgement. No bill can eliminate all construction risk, and excessive precision may create false confidence.

The quantity surveyor has ethical responsibilities to act competently, maintain impartiality in tender processes, disclose assumptions, protect confidential information and avoid knowingly misleading descriptions. Allowances should be reasonable and transparent. Omissions should be corrected promptly, with the effect on tenderers communicated fairly.

Regulatory requirements vary by jurisdiction, but the bill should be consistent with applicable building regulations, health and safety duties, environmental obligations, tax requirements and public-procurement rules. Contract advice should be coordinated with the appointed legal and procurement professionals where necessary.

16. Best-Practice Checklist

Before issuing a BoQ, confirm that:

• the contract form and measurement standard are identified;
• all documents have revision status and a coordinated register;
• descriptions are clear, measurable and specification-consistent;
• units and decimal precision are consistent;
• preliminaries do not duplicate measured work;
• provisional sums are justified and defined where possible;
• PC items distinguish supply from installation and attendance;
• daywork rates and record requirements are stated;
• schedules use consistent codes and identifiers;
• quantities have been independently checked;
• exclusions, assumptions and interfaces are recorded;
• addenda and tender queries are controlled; and
• the final bill is suitable for both tendering and later administration.

Chapter Summary

A bill of quantities converts coordinated design information into a structured commercial document for tendering, valuation and cost control. Its effectiveness depends on clear descriptions, appropriate units, traceable measurement, logical work sections and coordination with drawings and specifications. Preambles explain general measurement and pricing assumptions, while preliminaries cover project management and execution costs. Provisional sums address incompletely defined work; prime-cost items allow for selected goods not yet priced; and dayworks provide controlled valuation for instructed work that cannot reasonably be measured in advance.

Schedules strengthen coordination by linking repeated components and systems to unique identifiers. Quality assurance requires completeness, consistency, arithmetic checking, revision control and fair management of tender queries. Digital tools and BIM improve efficiency, but professional judgement remains essential. The central principle is transparent allocation: every significant obligation, allowance and uncertainty should be visible, understandable and contractually controlled.

Key Terms

Bill of quantities: A document describing and quantifying construction work for pricing and administration.

Taking-off: Extracting dimensions and quantities from design information.

Squaring: Multiplying dimensions to obtain an extended quantity.

Abstracting: Grouping similar measured items for transfer into the bill.

Preamble: A clause explaining measurement, pricing and general inclusion assumptions.

Preliminaries: Costs and obligations associated with managing and executing the project rather than forming permanent work.

Measured work: Construction work quantified using stated measurement rules.

Provisional sum: An allowance for work or expenditure insufficiently defined at tender stage.

Defined provisional sum: A provisional allowance described sufficiently for reasonable planning and pricing.

Undefined provisional sum: An allowance for work whose scope or conditions remain inadequately defined.

Prime-cost item: An allowance for the supply of selected goods or materials not finally chosen or priced.

Daywork: A contract method for valuing instructed work using recorded labour, plant and material inputs.

Schedule of works: A structured description of activities that may not include detailed measured quantities.

Schedule of rates: A list of agreed rates for defined work items.

Activity schedule: A priced allocation of a contract sum among activities.

Attendance: Support, access, supervision or facilities provided for another trade or specialist operation.

Timesing: Applying a multiplication factor to repeated dimensions or elements.

Revision control: The process of identifying, recording and managing changes to project information.

Review Questions

Short Answer Questions

1. State four principal functions of a bill of quantities.
2. What information should a good work-item description contain?
3. Distinguish between a provisional sum and a prime-cost item.
4. Why should preliminaries be separated from measured work?
5. Identify three records normally required to support daywork valuation.

Long Answer Questions

1. Explain the process of preparing a coordinated bill of quantities from drawings and specifications.
2. Discuss the purpose of preambles and evaluate the risks of using vague or contradictory preamble clauses.
3. Explain how schedules for doors, finishes or equipment improve procurement and contract administration.
4. Analyse the effects of incomplete design information on provisional sums, tender comparison and final cost.
5. Describe a quality-assurance system for checking a BoQ before issue to tenderers.

Analytical / Application Questions

1. A project contains 60 identical floor tiles, each covering 0.36 m². Explain how the quantity should be measured and identify additional information needed before preparing the final BoQ item.
2. A contractor claims that installation is included in a prime-cost allowance for sanitary fittings, while the BoQ measures only the supply allowance. Analyse the issue and propose a fair contractual approach.
3. During excavation, an unforeseen service is discovered. Design a procedure using provisional sums and/or dayworks that controls authorisation, records, valuation and communication with the client.

Multiple Choice Questions with Answers

Question 1

Which document most directly establishes the measurement and pricing assumptions applying to a bill section?

A. Preamble

B. Door schedule

C. Site diary

D. Completion certificate

Correct Answer: A. Preamble

Question 2

A rectangular concrete element is 10 m long, 0.6 m wide and 0.25 m deep. What is its volume?

A. 0.15 m³

B. 1.50 m³

C. 2.50 m³

D. 15.00 m³

Correct Answer: B. 1.50 m³

Question 3

What is the principal purpose of a prime-cost item?

A. To price excavation risk

B. To allow for selected goods not finally priced or selected

C. To record labour hours worked

D. To describe site management costs

Correct Answer: B. To allow for selected goods not finally priced or selected

Question 4

Which cost would normally be classified as a preliminary?

A. Volume of structural concrete

B. Area of wall plaster

C. Site establishment and welfare facilities

D. Number of internal doors

Correct Answer: C. Site establishment and welfare facilities

Question 5

Which feature most improves the reliability of a measured quantity?

A. Removing drawing references

B. Using unexplained abbreviations

C. Traceable dimensions linked to current documents

D. Combining different materials into one item

Correct Answer: C. Traceable dimensions linked to current documents

Question 6

Daywork is most appropriately used when work is:

A. Fully designed and easily measured before tender

B. Instructed but not reasonably measurable or priceable in advance

C. Always included in general preliminaries

D. Limited to the purchase of selected appliances

Correct Answer: B. Instructed but not reasonably measurable or priceable in advance

Question 7

What should normally be measured separately from the supply allowance of a prime-cost item?

A. Installation and associated attendance

B. The client’s financing cost

C. The contractor’s tender security

D. The drawing revision number

Correct Answer: A. Installation and associated attendance

Question 8

A provisional sum is primarily used to:

A. Hide an omission from the tender documents

B. Allow for work not sufficiently defined at tender stage

C. Replace all measured quantities

D. Determine the contractor’s tax liability

Correct Answer: B. Allow for work not sufficiently defined at tender stage

Question 9

For four identical elements each measuring 2.5 m³, what is the total quantity?

A. 0.625 m³

B. 2.50 m³

C. 6.50 m³

D. 10.00 m³

Correct Answer: D. 10.00 m³

Question 10

Which practice best supports fair tendering?

A. Issuing scope-changing answers privately to one tenderer

B. Allowing each tenderer to use a different measurement basis

C. Issuing relevant clarifications to all tenderers through controlled addenda

D. Omitting revision dates from drawings

Correct Answer: C. Issuing relevant clarifications to all tenderers through controlled addenda