Bill of quantities
A bill of quantities (BoQ) is a standardized document in the construction industry that lists items of work with detailed descriptions, measured quantities, and units, enabling contractors to price the scope of a project accurately for tendering and contracting.[1] It serves as the basis for remeasurement contracts, where the final payment is adjusted based on actual quantities executed, and provides a schedule of rates for valuing variations and interim payments.[2] Prepared by quantity surveyors or cost managers during the pre-construction phase, a BoQ draws from project drawings, specifications, and schedules, following established methods of measurement such as the New Rules of Measurement (NRM) for building works or standard engineering practices.[1] These documents typically organize items elementally (e.g., by building components like foundations or roofing), by trade sections, or by work packages, including preliminary items as lump sums for mobilization and time-related charges.[2] The preparation ensures net quantities are measured as fixed in place, with no deductions for small voids, and full details on materials, dimensions, and fixing methods to minimize ambiguities.[1] The primary purposes of a BoQ include facilitating competitive tendering by providing all bidders with identical information, supporting cost control and budgeting, enabling fair valuation of changes during execution, and aiding post-contract analysis for future projects.[2] Originating in the United Kingdom during the 19th century alongside the emergence of the quantity surveying profession, BoQs have evolved with contract forms like those from FIDIC and JCT, becoming essential in civil engineering and building projects worldwide to promote transparency and reduce disputes.[3] Despite advancements in digital tools, they remain a cornerstone for risk management and accurate financial forecasting in complex construction endeavors. As of 2025, advancements including Building Information Modeling (BIM) and artificial intelligence (AI) have enabled digital BoQ preparation with automated quantity extraction, further supporting accuracy and collaboration.[4]Introduction
Definition
A bill of quantities (BoQ), also referred to as a BQ, is a standardized document used primarily in the construction industry to itemize the materials, labor, parts, and associated services required for a project, along with their respective quantities and descriptive specifications.[1] It serves as a comprehensive schedule that enables precise quantification of work elements, ensuring consistency in project scoping and cost estimation.[5] Typically prepared during the pre-construction phase, the BoQ is compiled by a quantity surveyor or cost consultant based on architectural drawings, specifications, and engineering details to define both the quality and extent of works.[6] According to the Royal Institution of Chartered Surveyors (RICS) New Rules of Measurement for building works (NRM2), a BoQ is defined as "a list of items providing detailed identifying descriptions and firm quantities of the work comprising a contract," which fully describes and accurately represents the quantity and quality of works to be carried out.[1] This document distinguishes itself from related tools like bills of materials (BOM) by incorporating not only physical components but also labor, provisional sums, and non-measurable items, thereby supporting holistic project valuation.[5] In practice, BoQs are most commonly applied to larger-scale projects where competitive tendering is involved, as they standardize the basis for contractor pricing and minimize discrepancies in bid submissions.[6] The structure of a BoQ adheres to established standards such as NRM2, organizing content into sections like preliminaries, measured works, and dayworks, with each item measured in appropriate units (e.g., square meters for flooring or linear meters for piping) to facilitate accurate tendering and post-contract administration.[1] By providing firm or approximate quantities—depending on project certainty—the BoQ mitigates risks associated with estimation errors and forms the foundation for interim payments, variations, and final account settlements.[7]Historical Development
The origins of the bill of quantities (BoQ) can be traced to the late 18th and early 19th centuries in the United Kingdom, emerging as a response to the rapid industrialization and expansion of construction projects during the Industrial Revolution. Prior to this period, construction cost estimation was often ad hoc, with measurements typically conducted after work completion to facilitate payments to tradesmen. The introduction of the BoQ marked a shift toward systematic pre-construction documentation, listing materials, labor, and quantities to enable more accurate tendering and cost control. Early practitioners, known as "measurers" or "custom surveyors," prepared these documents for master builders, with the earliest recorded quantity surveying firm, Henry Cooper and Sons, established in 1785.[3][8] By the mid-19th century, the BoQ became formalized as a standard tool in the burgeoning profession of quantity surveying, driven by the need for independent cost estimation in large-scale infrastructure projects such as railways and bridges. The term "quantity surveyor" first appeared in records in 1859, coinciding with the profession's transition from trade-specific roles to impartial consultants who prepared BoQs for competitive bidding. This development was further supported by the founding of the Royal Institution of Chartered Surveyors (RICS) in 1868, which professionalized surveying practices and promoted standardized measurement methods.[3][9] In the 20th century, the BoQ evolved through standardization efforts, including the publication of the first Standard Method of Measurement (SMM) in 1922 by the Royal Institution of Chartered Surveyors, which provided uniform rules for quantifying work items. Post-World War II reconstruction accelerated its adoption for cost planning and value engineering. The late 20th and early 21st centuries saw technological advancements, such as computer-aided design and software like CostX, transforming manual BoQ preparation into automated processes integrated with Building Information Modeling (BIM). Despite these changes, the core purpose of the BoQ in facilitating transparent tendering and risk management has remained central to construction procurement worldwide.[8][10]Purpose and Importance
Role in Tendering
The bill of quantities (BoQ) serves as a central document in the tendering process for construction projects, providing a standardized breakdown of the work items, materials, labor, and quantities required, which enables contractors to submit comparable and accurate bids. Prepared typically by a quantity surveyor during the contractor engagement stage, the BoQ is derived from project drawings, specifications, and schedules, ensuring that all potential bidders have a consistent and detailed scope of work to price. This standardization is essential in traditional procurement routes, where the BoQ forms part of the tender package alongside other contract documents, facilitating a competitive bidding environment by minimizing variations in interpretation among contractors.[1] In the tendering workflow, the BoQ allows contractors to apply unit rates and prices to each measured item—such as cubic meters for excavations or linear meters for piping—resulting in a total tender sum that can be directly compared across submissions. It supports both firm BoQs, used in lump-sum contracts where quantities are fixed and priced definitively, and approximate BoQs, employed in remeasurement contracts where provisional quantities are adjusted post-contract based on actual work executed. By codifying items with precise descriptions, units of measurement, and levels of detail (e.g., material types and dimensions), the BoQ promotes transparency and reduces the risk of discrepancies, enabling clients to evaluate tenders on a like-for-like basis during analysis and normalization.[1][11] The BoQ's role extends to enhancing fairness and accountability in tendering, as it mitigates opportunities for unbalanced bidding by requiring explicit pricing for each element, including preliminaries like site management costs and provisional sums for uncertain work. In single-stage tendering processes common to traditional contracts, the BoQ ensures that design information is sufficiently complete before inviting bids, thereby lowering risk premiums in contractor submissions and supporting effective cost control from the outset. Adherence to standards such as the RICS New Rules of Measurement (NRM2) governs the BoQ's structure, ensuring consistency in measurement rules and item ordering (e.g., from cubic to enumerated works), which further streamlines tender evaluation and contract formation.[1][11]Cost Management
In cost management, the bill of quantities (BoQ) serves as a foundational tool for establishing price certainty and enabling detailed cost planning prior to construction commencement. By itemizing materials, labor, and other resources with measured quantities, the BoQ allows quantity surveyors to develop accurate cost estimates that form the basis of the project budget, reducing uncertainties and promoting competitive tendering among contractors.[12] This pre-contract function facilitates risk mitigation for both clients and contractors, as unit rates derived from the BoQ provide a standardized framework for pricing, ensuring alignment with overall project financial objectives.[13] During the construction phase, the BoQ plays a critical role in post-contract cost control by providing a baseline for monitoring expenditures against the approved budget. Quantity surveyors use the BoQ to track progress through interim valuations, where payments are certified based on the measured quantities of completed work multiplied by agreed unit rates, typically on a monthly basis.[14] This process enables early detection of variances, such as overruns in material costs—which often constitute 60-70% of total expenses—allowing for timely adjustments like resource reallocation or efficiency improvements to keep the project within financial limits.[15] For instance, in roadway projects, the BoQ supports summation of unit costs to verify total expenditures, helping maintain budgetary adherence.[12] The BoQ also enhances cost management of variations and changes, which are common in construction due to design modifications or unforeseen site conditions. It supplies a schedule of rates for remeasuring and valuing alterations, ensuring that additional costs are calculated consistently and agreed upon before implementation, thereby minimizing disputes and controlling escalation.[13] Under standard contracts like the RIAI Form, the BoQ links variations to the original cost plan, with quantity surveyors reviewing discrepancies to prevent unnecessary budget inflation.[14] Contingency allowances, often around 5% of the contract sum and tied to BoQ elements, further support this by covering predictable risks without derailing overall cost objectives.[14] Ultimately, the BoQ contributes to final account settlement by reconciling actual quantities and costs against the tendered figures, incorporating adjustments for variations, claims, and provisional sums. This systematic approach ensures comprehensive financial closure, with tools like earned value analysis integrated via BoQ data to assess cost performance and forecast completion expenses.[16] By fostering transparency and accountability throughout the project lifecycle, the BoQ not only controls costs but also enhances profitability and efficiency for construction enterprises.[13]Preparation Process
Steps in Creating a BoQ
The preparation of a Bill of Quantities (BoQ) follows a structured process to ensure accuracy, consistency, and compliance with industry standards such as the New Rules of Measurement (NRM2) published by the Royal Institution of Chartered Surveyors (RICS).[1] The preparation process varies by region and project type; in the UK, it follows standards such as the New Rules of Measurement (NRM2), while civil engineering projects internationally often adhere to CESMM4 or FIDIC guidelines.[17] This process typically involves three main phases: pre-measurement, measurement, and compilation, each designed to translate project documentation into a quantifiable document that facilitates tendering and cost control.[1] The steps emphasize detailed review of drawings and specifications to capture all work elements, including materials, labor, and incidental items, while adhering to rules for units, descriptions, and exclusions.[1] In the pre-measurement phase, the initial focus is on project planning and information gathering. The project team determines the BoQ structure using a work breakdown structure (WBS), such as elemental, work section, or works package breakdowns, to organize the content logically.[1] Essential project particulars are collected, including the title, location, contract duration, and scope of works, alongside specifications and drawings like site plans, sections, and elevations from clients and designers.[1] The site context is analyzed, describing existing buildings, constraints, and environmental factors, while reviewing material types, quality standards, fixing methods, and dimensions to ensure comprehensive coverage.[1] Items are codified using a consistent framework, such as NRM1 codes, often with computerized systems to enable traceability and efficient data management.[1] The measurement phase involves quantifying the work based on NRM2 rules to produce accurate take-offs. Work is measured net as fixed in its final position, incorporating allowances for laps, joints, waste, and other additions, with dimensions stated to the nearest 10 mm.[1] Quantities are calculated in appropriate units—such as cubic meters (m³) for concrete, square meters (m²) for wall areas, linear meters (m) for pipes, or numbers (nr) for fixtures—grouped by elements, work sections, or packages following tabulated rules in NRM2 Part 3.[1] Descriptions must detail the type, quality, dimensions, and fixing methods, including incidental works like disposal of debris or temporary supports unless explicitly excluded.[1] Specific details, such as pitch for sloping roofs or girth for curved elements, are noted, and deductions for voids are avoided only for those below specified thresholds that vary by work type and section, such as ≤0.05 m³ in concrete or ≤1 m² in certain building works, as detailed in the relevant NRM2 rules.[1] Measurements reference relevant work sections, for example, Section 11 for in-situ concrete or Section 18 for complete buildings and building works, ensuring drawings provide major dimensions and material specifications.[1] During compilation, the measured data is assembled into a coherent BoQ document. The structure uses hierarchical levels: Level 1 for item types (e.g., headings), Level 2 for specifics, and Level 3 for notes or details, with each bill formatted on new sheets per element or work section.[1] Key sections include the form of tender, preliminaries, measured works, provisional sums, and a grand summary, with items listed in order of cubic, square, linear, enumerated, and itemised within each element or work section, with labour-only items preceding labour and plant entries.[1] Descriptions incorporate units, associated works (e.g., joints and fixings), and cross-references to drawings or specifications, using fixed or time-related pricing where applicable.[1] Quantities are aggregated as needed, exclusions stated clearly, and provisional items handled separately; totals are carried forward across pages to a final summary for overall project costing.[1] This phase ensures the BoQ is tender-ready, promoting fair competition and accurate valuation.[1]Involved Professionals
The preparation of a Bill of Quantities (BoQ) in construction projects primarily involves quantity surveyors, who serve as the core professionals responsible for measuring and documenting the quantities of materials, labor, and other resources required. Quantity surveyors, often employed by the client or as independent consultants, analyze architectural drawings, engineering specifications, and project plans to compile the BoQ, ensuring compliance with standards such as the New Rules of Measurement (NRM) issued by the Royal Institution of Chartered Surveyors (RICS).[18][5] Their role extends to preparing tender documents, managing cost risks, and facilitating value engineering to optimize project budgets without compromising quality.[18] Architects and engineers contribute significantly to the BoQ process by providing the foundational design elements and technical specifications that quantity surveyors rely on for accurate quantification. Architects develop the overall project layout and aesthetic details, while engineers focus on structural, mechanical, or electrical components, both ensuring that their outputs align with regulatory requirements and site conditions to enable precise BoQ compilation.[5] In collaborative team environments, these design professionals work alongside quantity surveyors during the pre-tender phase to resolve discrepancies in drawings or specifications that could affect quantity takeoffs.[19] On the contractor's side, estimators play a key role in utilizing and sometimes refining the BoQ during the bidding process, where they apply unit rates, labor costs, and overheads to the quantified items to generate competitive tender prices. While quantity surveyors typically handle the initial neutral measurement for the client, contractor estimators may perform remeasurements or adjustments based on site-specific factors, using tools like digital takeoff software to verify quantities.[5][20] This division ensures the BoQ serves as an impartial baseline for fair tendering, with estimators focusing on cost application rather than creation.[21] Project managers or cost consultants may oversee the BoQ preparation to coordinate inputs from the multidisciplinary team, ensuring timelines and integration with broader project controls, though their involvement is more supervisory than hands-on measurement. In modern practices, building information modeling (BIM) specialists increasingly support all these roles by automating quantity extractions from 3D models, enhancing accuracy and reducing manual errors across the team.[19]Structure and Components
Standard Format
The standard format of a Bill of Quantities (BoQ) follows established measurement rules to ensure consistency, clarity, and comparability in construction tendering and cost management. In the United Kingdom and regions adopting similar practices, the Royal Institution of Chartered Surveyors (RICS) New Rules of Measurement (NRM2, 2nd edition, 2021) provides the primary framework for detailed measurement of building works, organizing the BoQ into a structured document that includes a form of tender, summary, preliminaries, measured works, and additional sections for risks and provisional items.[1] This format emphasizes a hierarchical breakdown, often using elemental, work section, or work package structures with codified levels (e.g., up to six levels including project, bill, and elements) to facilitate accurate pricing and valuation.[1] The BoQ is typically presented as a tabular document with vertical columns for systematic data entry, starting from the left with an item number for reference, followed by a detailed technical description of the work or material, the unit of measurement, the quantity, the unit rate provided by the tenderer, and the extended amount (quantity multiplied by rate).[22] Item descriptions must be precise, specifying scope, type, quality, dimensions, fixing methods, and location, while units adhere to metric standards such as meters (m), square meters (m²), cubic meters (m³), numbers (nr), tonnes (t), or items, depending on the work type.[1] Rates are entered by contractors as fixed charges, time-related charges (e.g., per week or month), or per unit, forming the basis for the contract sum, variations, and interim payments.[1] Pages include running totals carried forward, with section summaries and a grand total aggregating all bills into the overall project cost.[22] Core sections of the BoQ under NRM2 are outlined below, ensuring comprehensive coverage from project preliminaries to specialized provisions:| Section | Description | Key Components |
|---|---|---|
| Form of Tender | Captures the contractor's total tender price, which may become the contract sum upon acceptance. | Single entry for overall bid amount.[1] |
| Summary | Provides an overview by listing all bill sections with their subtotals and grand total. | Placed at the front or end; facilitates quick cost assessment.[1] |
| Preliminaries | Details project-specific requirements and fixed/time-related costs not tied to measured quantities. Divided into Part A (information and requirements) and Part B (pricing schedule). | Part A: Site details, contract conditions, health and safety, temporary works. Part B: Fixed charges (e.g., mobilization), time-related items (e.g., site management per week).[1] |
| Measured Works | Quantifies and describes the main construction items by trade or element, following tabulated rules in NRM2 Part 3. | Work sections (e.g., 3: Demolitions, 11: In-situ Concrete Works, 38: Mechanical Services); includes off-site manufactured materials; ordered by volume (cubic, linear, enumerated).[1] |
| Risks | Allocates fixed prices for residual, non-measurable risks transferred to the contractor. | Lists specific retained risks like unforeseen ground conditions.[1] |
| Provisional Sums | Includes lump sums for undefined or partially defined work, often with allowances for dayworks. | Undefined (broad scope) or defined (specific items); supports variations.[1] |
| Credits | Deducts value of materials or items arising from the works that the contractor can reuse or sell. | Itemized credits for salvageable materials.[1] |
| Dayworks | Schedules rates for labor, materials, and plant used in unforeseen or additional works valued on a time basis. | Percentage additions for overheads and profit; referenced to contract clauses.[1] |
| Annexes | Supplementary schedules or documents, such as specifications or drawings references. | Optional; enhances detail without altering core format.[1] |
Key Elements
The key elements of a bill of quantities (BoQ) form a standardized structure that ensures clarity, consistency, and completeness in quantifying construction works for tendering and contract administration. According to the Royal Institution of Chartered Surveyors (RICS) New Rules of Measurement (NRM) 2 (2nd edition, 2021), these elements provide a coordinated list of items with identifying descriptions and quantities, enabling contractors to prepare accurate tenders.[1] The primary components include the form of tender, summary, preliminaries, measured works, risks, provisional sums, credits, dayworks, annexes, and non-measurable works, each serving distinct functions in the document's overall framework.[1] The form of tender records the contractor's overall tender price, which typically becomes the contract sum upon acceptance, providing a binding financial commitment.[1] Following this, the summary aggregates totals from all BoQ sections, listing section breakdowns and overall pricing to facilitate quick financial oversight.[1] Preliminaries constitute a critical preliminary section covering project-specific details such as the title, location, duration, site establishment, management requirements, and contract conditions; these are divided into fixed charges (e.g., one-off items like site mobilization) and time-related charges (e.g., weekly costs for supervision), ensuring all non-measurable overheads are accounted for.[1] The core of the BoQ lies in the measured works, which detail quantified items across standardized work sections (e.g., demolitions, concrete works, mechanical services), measured net as fixed with dimensions to the nearest 10mm and voids deducted where applicable.[1] Each item includes identifying descriptions specifying material type, quality, critical dimensions, fixing methods, and background nature, using metric units such as meters (m) for lengths, square meters (m²) for areas, cubic meters (m³) for volumes, numbers (nr) for discrete items, and tonnes (t) for weights.[1] Risks enumerate residual uncertainties transferred to the contractor, while provisional sums allocate allowances for undefined or partially designed work, and credits deduct values for reusable materials from demolitions or refurbishments.[1] Additional elements include dayworks for provisional rates on time-based or specialist tasks not otherwise quantified, and annexes for supplementary information like performance specifications or drawings.[1] Non-measurable works, such as contractor-designed portions, are handled separately to maintain the BoQ's focus on surveyor-measured items.[1] Pricing integrates labor, materials, and overheads into unit rates, with items ordered by value for efficiency, supporting applications in cost planning, variations, and interim valuations.[1] This structure promotes uniformity, as outlined in NRM 2's tabulated rules, which specify levels of detail for descriptions to avoid ambiguity.[1]Types of Bills of Quantities
Elemental BoQ
An elemental bill of quantities (BoQ) is a structured document that organizes construction work items by major building elements, such as substructure and superstructure, rather than by trade or operational sequence. This approach facilitates detailed cost planning and analysis by breaking down the project into functional or physical components, allowing for approximate quantities and unit rates to be applied early in the design process. It is particularly useful for establishing cost targets and evaluating design alternatives before full specifications are available.[24][25] The primary purpose of an elemental BoQ is to support cost management during initial project stages, such as RIBA Stages 0-2, by providing a hierarchical cost breakdown that ensures affordability and value for money. It enables quantity surveyors to distribute the overall budget into element-specific targets, identify potential overruns, and compare costs against benchmarks from similar projects. Unlike more detailed tendering documents, it relies on element unit quantities (e.g., square meters of floor area) and rates derived from historical data, promoting consistency in estimating across projects. This method aids in decision-making for design development and procurement strategies, transitioning into fuller BoQs as the project matures.[24][26] In terms of structure, an elemental BoQ follows a standardized hierarchy aligned with guidelines like the Royal Institution of Chartered Surveyors' New Rules of Measurement (NRM) or the Building Cost Information Service (BCIS) Elemental Standard Form of Cost Analysis. It typically includes group elements (Level 1), elements (Level 2), sub-elements (Level 3), and components (Level 4), with each item described, quantified, and costed. Exclusions such as professional fees, main contractor preliminaries, and inflation are noted separately, while inclusions cover materials, labor, plant, and subcontractor costs. Measurement units vary by element, such as meters for walls or numbers for doors, ensuring precise yet approximate quantification.[24][26][25] Key group elements in an elemental BoQ, as defined in NRM, encompass the following major categories:| Group Element | Description | Examples of Sub-elements |
|---|---|---|
| 0: Facilitating Works | Site preparation and enabling activities | Demolition, temporary works |
| 1: Substructure | Foundations and ground-level support | Excavation, ground floors, basements |
| 2: Superstructure | Above-ground structural elements | Frame, upper floors, external walls, roof |
| 3: Internal Finishes | Interior surface treatments | Wall finishes, ceilings, flooring |
| 4: Fittings, Furnishings, and Equipment | Movable or fixed building contents | Fixtures, specialist equipment |
| 5: Services | Building systems and utilities | Electrical installations, HVAC, plumbing |
| 6: Prefabricated Buildings | Modular or off-site constructed units | Complete prefabricated modules |
| 7: Work to Existing Buildings | Alterations and integrations | Refurbishments, extensions |
| 8: External Works | Site and landscape features | Roads, landscaping, drainage |