How to Prepare a Bill of Quantities (BOQ) in Ghana

A Bill of Quantities (BOQ) is a priced schedule of all the work items in a construction project. Done correctly, it becomes the financial backbone of a contract — the document that controls payments, defends variations, and anchors disputes. Done poorly, it creates gaps that contractors exploit.

This guide walks through the full BOQ preparation process specifically in the Ghana context, covering the measurement basis, input pricing, common mistakes, and what makes a BOQ defensible when challenged on site.

1. Understand the Purpose Before You Start Measuring

A BOQ is not just a quantity list — it is a priced document that performs multiple functions:

• Tender evaluation: enables like-for-like comparison between contractors
• Contract sum basis: the priced BOQ forms part of the contract
• Interim payments: valuations are measured against it
• Variation costing: adds or omits items at priced rates

If you treat the BOQ as a rough list, it will fail at all of these purposes. The level of detail you put in determines how much protection the client has during construction.

2. Choose Your Measurement Method

Ghana's QS practice draws predominantly from the RICS Standard Method of Measurement (SMM7) and increasingly NRM2, adapted to local practice. In practice, most Ghanaian QSs follow firm-level conventions more than strict adherence to a published standard — which is itself a problem, because inconsistency creates disputes.

Key measurement rules that often trip up junior QSs in Ghana:

• Excavation: measured net in place (not bulked). Any allowance for bulkage and compaction is a pricing decision, not a measurement one.
• Concrete: measured net finished volume. Do not include formwork waste in the concrete quantity.
• Blockwork: measured as superficial area (m²), deducting openings over 0.5 m².
• Reinforcement: measured in tonnes, including laps and hooks — often sourced from bar bending schedules.
• Plastering/rendering: measured as superficial area (m²) net, deducting openings.

3. Structure Your Work Sections Properly

A well-structured BOQ groups work into logical sections. For most building projects in Ghana, a typical structure follows:

1. Preliminaries & General Items
2. Site Preparation & Earthworks
3. Substructure (foundation, ground slab)
4. Superstructure (frame, walls, floors, roof)
5. External Works & Drainage
6. Finishes
7. Services (M&E, plumbing)
8. Provisional Sums & PC Rates

Jumbling sections together is one of the most common errors. A contractor who cannot track payments back to a specific work section will dispute every valuation.

4. Input Pricing for Ghana: What Changes Everything

The quantities are only half the story. The rates you apply determine whether your BOQ reflects the market or misrepresents it. In Ghana, three factors dominate rate volatility:

• Region: Material prices in Accra, Takoradi, and Kumasi diverge by 15–30% for the same product, driven by haulage and supplier concentration.
• Rate date: With Ghana's inflation history, a rate from 12 months ago can understate current cost by 20–40%.
• Supplier selection: "Lowest price" and "most reliable supplier" are often not the same. Your pricing basis should be explicit.

The single most common cause of BOQ disputes in Ghana is not measurement error — it is pricing assumptions that were never made explicit. If your rate for concrete is based on a supplier in Tema but the project is in Kumasi, the contractor is either absorbing the difference or claiming a variation. Either outcome is avoidable.

5. Preliminaries: The Section Most QSs Underprice

Preliminaries cover time-related and project-wide costs that don't attach to any specific trade item. They typically run 10–18% of the construction cost for medium-scale projects in Ghana. Common items:

• Site establishment and mobilisation
• Project management and supervision
• Temporary facilities (site office, water, power)
• Plant hire and fuel for general operations
• Health, safety, and welfare provisions
• Insurance and performance bond premiums

Underpricing or omitting preliminaries is a strategic mistake. Contractors who win on a thin preliminaries budget either cut corners on site or come back with claims. A well-priced preliminary section protects the project programme.

6. Markup: Overhead, Profit, and Contingency

After the direct cost build-up, the BOQ final sum includes markup. Typical ranges for Ghana:

• Overhead: 8–15% (firm's fixed costs allocated to this project)
• Profit: 5–10%
• Contingency: 5–10% for normal projects; higher for complex or high-risk scope

Contingency is not a reward for the contractor. It is a controlled reserve for genuinely unforeseen scope changes. Make it explicit and contractually defined.

7. Export and Documentation

A BOQ that cannot be handed to a client or contractor in a clean, navigable format defeats its own purpose. At minimum, the exported document should:

• Show quantities and rates separately (not just lump sums)
• Identify the pricing date and region basis
• Reference the measurement rules applied
• Be signed or stamped by the QS