Types of Bill of Quantities in Construction
Construction projects involve countless moving parts – materials, labour, equipment, and timelines, just to name a few. The Bill of Quantities (BoQ) helps plan and control all these aspects. Specifically, it documents what work needs to be done, how long each task should take, how many materials it requires, as well as estimates the cost of construction.
Having said that, not all construction projects are the same, and neither are their documentation needs. Various situations call for different approaches to quantity measurement and cost estimation. Therefore, you may come across numerous types of Bill of Quantities in construction. Below, we explain the most common formats: their purpose, when they are used, and their benefits.
1. Firm (Detailed) Bill of Quantities
A Firm Bill of Quantities is the most precise of all BoQs. It reflects the accurate measurements and itemisation of materials and works.
This type of BoQ can be created only after finalising the project design when contractors know exactly what they’re pricing and, therefore, are able to provide accurate lump-sum bids. While creating this level of detail requires significant upfront investment in time and resources, it pays dividends throughout the project lifecycle.
Benefits of the Firm Bill of Quantities:
• Provides excellent financial control and budget certainty;
• Minimises disputes over scope and pricing;
• Creates a reliable baseline for assessing any changes;
• Reduces the risk of cost overruns due to unclear specifications.
2. Preliminary (Approximate) Bill of Quantities
The Preliminary Bill of Quantities provides reasonable cost estimates based on partly available information, i.e. before the detailed designs are complete. This approach allows construction projects to get started when time constraints are tight or when certain aspects of the work are unknown (for example, when ground conditions remain uncertain until excavation works begin).
Preliminary BoQ feature rates for different types of work instead of a single lump sum. As the project progresses and more details become available, contractors are likely to adjust initial quantities. As a result, this type of Bill of Quantity is not the most accurate in terms of timelines and budget.
Benefits Preliminary Bill of Quantities:
• Enables reducing preparation time and starting projects faster;
• Allows tendering to begin before the final design is complete;
• Provides cost flexibility for projects with uncertain elements;
• Reduces upfront documentation costs;
• Provides a broad financial overview, which supports making informed decisions.
3. Provisional Bill of Quantities
Since construction projects don’t always go exactly according to plan, the Provisional Bill of Quantities acknowledges this reality. In other words, it includes items that might or might not be needed as the construction progresses.
This type of Bill of Quantities makes sense when you’re dealing with challenging sites or projects where some work elements remain uncertain (for example, in the case of extra rock excavation or unforeseen drainage). All provisional quantities are flagged for re-measurement in the later phases of construction.
Benefits of Provisional Bill of Quantities:
• Provides flexibility for project elements with a high degree of uncertainty;
• Reduces the risk of budget surprises from unforeseen conditions;
• Makes it possible to select a contractor and start the project earlier
4. Elemental Bill of Quantities
Elemental Bills of Quantities organise work items in groups according to building components, such as foundations, walls, roofing, electrical systems, and so on. Inside these groups, the items usually represent the construction sequence, i.e. they show the order in which activities will take place on-site.
This systematic approach helps project teams better understand how different construction components relate to each other and plan their work sequence accordingly. Besides, it makes cost analysis much easier. For instance, if you see that the façade takes a significant portion of the budget, you can decide whether to swap materials or finishes.
Benefits of Elemental Bill of Quantities:
• Facilitates logical work sequencing and project planning;
• Enables easy cost comparison between different building elements;
• Improves coordination between construction phases;
• Helps contractors provide cost estimations for the key construction sections.
5. Operational Bills of Quantities
The Operational Bill of Quantities has a workflow-centred approach, i.e. it organises work according to specific construction operations rather than building elements. Each operation is then broken down into its component parts.
This format is particularly useful for complex projects since it helps project managers see what combination of people, equipment, and materials each operation requires. This way, they can make more accurate decisions regarding resource planning and scheduling. On top of it, the Operational BoQs help optimise construction sequences and analyse productivity across different operations.
Benefits of Operational Bills of Quantities:
• Provides detailed resource requirements for each construction operation;
• Contributes to precise resource planning and allocation;
• Improves productivity analysis and its optimisation;
• Streamlines coordination between labour, equipment, and materials.
6. Trade Bill of Quantities
The Trade Bill of Quantities organises work according to specialised construction trades, such as electrical, plumbing, carpentry, masonry, and others. It comes in handy for projects that rely heavily on specialised subcontractors. Each trade gets its own section in the Bill with work items arranged in their typical sequence. As a result, all the involved specialists can quickly identify their scopes while still seeing how their work fits into broader construction phases.
Benefits of Trade Bill of Quantities:
• Simplifies subcontractor bidding and management processes;
• Enables trade-specific cost analysis and control;
• Facilitates coordination between different construction specialists.
7. Final Bill of Quantities
Unlike other types of Bills of Quantities, which are made before the construction begins, the Final Bill is issued after the project reaches completion. Because it is not uncommon to have discrepancies between what was originally planned and what occurred during construction, the Final BoQ helps document all actual costs, changes, and variations.
At the same time, it provides the foundation for final payments and dispute resolutions. Thanks to this document, all the parties can clearly see what work was performed and what it cost.
Benefits of the Final Bill of Quantities:
• Ensures accurate final cost accounting and payments;
• Provides documentation for project audits;
• Creates historical data for future project planning;
• Facilitates transparent dispute resolution and project closure.
Choosing the Right Types of Bill of Quantities
An appropriate type of Bill of Quantities will depend on your project circumstances, especially timeline constraints and design completion levels. While projects with complete designs and fixed budgets can benefit from Firm BoQs, building developments with evolving requirements might need provisional or approximate formats.
In addition, BoQ types can reinforce project management at different levels – Elemental Bills of Quantities may contribute to design optimisation, Operational ones enable stricter resource control, Trade BoQ is responsible for subcontract procurement, and so on.
Whatever format you may need, PEJA Surveying is at your disposal. Our team of professional Quantity surveyors understands that each construction project has unique requirements. We are happy to provide documentation designed to support its successful delivery.
Don’t hesitate to contact us and find out how we can help keep your construction on track and budget.
