A four-bedroom duplex cannot be priced reliably from its bedroom count alone. The useful starting point is an agreed design, total floor area, site information and finish specification. Ask a quantity surveyor to turn those into a dated estimate with clear inclusions.
Two four-bedroom homes can have very different staircases, living rooms, structural spans, bathrooms and external works. An attractive headline figure is not a budget until you know what it buys.
The information to assemble first
- Location and access: where materials will be delivered, available storage and access constraints.
- Drawings: a coordinated design and stated revision, with floor areas measured on a consistent basis.
- Site investigations: the information the design team needs to specify the foundation and drainage.
- Finish schedule: doors, windows, roofing, sanitary fittings, ceilings, tiles and other selected systems.
- Completion definition: shell, finished building or an occupied home with external services and fittings.
The RICS cost-prediction standard is a useful reference for disciplined estimating. It does not provide Nigerian house prices. Local rates still need a dated, project-specific basis.
Plot area is not building floor area
A 500-square-metre plot does not mean a 500-square-metre house. Nor does a 125-square-metre footprint automatically establish the measured total area of every design. Ask the architect and quantity surveyor to identify the area definition used in each estimate.
When someone quotes a rate per square metre, ask which area it multiplies and which work it covers. Otherwise the apparent precision hides a different scope.
Illustration: why a lower headline quote can cost more
The following figures are invented solely to demonstrate comparison. They are not September 2026 market rates and should not be used to fund a duplex.
| Item | Quote A | Quote B |
|---|---|---|
| Headline amount | NGN 90 million | NGN 98 million |
| Priced omissions needed for comparison | NGN 12 million | NGN 2 million |
| Comparable total before other project costs | NGN 102 million | NGN 100 million |
Here, the cheaper headline becomes the more expensive comparable quote. In a real tender, the missing items must be specified and priced, not filled with a convenient guess.
The whole-project budget
| Budget heading | Examples to confirm |
|---|---|
| Land and transaction | Purchase, investigations and applicable transfer costs |
| Design and permissions | Professional appointments, investigations and assessed approvals |
| Building works | Structure, roof, finishes and building services |
| External works | Access, drainage, boundary work and specified utilities |
| Occupation | Furniture, appliances and items outside the building contract |
| Risk and time | Identified uncertainty, escalation exposure and financing where relevant |
Have the cost adviser explain any contingency and what risks it covers. A reserve should not conceal known work that has simply been left out.
How many blocks and cement bags will you need?
Use a take-off from the design and specification. Wall lengths, heights, openings, block type, concrete quantities and construction system all matter. A generic four-bedroom allowance can lead to overbuying, shortages or a false sense that a materials-only budget is complete.
Read how to read a house BOQ before comparing quantities from different contractors.
Make the estimate usable during construction
Record the estimate date, quotation validity and assumptions about procurement timing. Agree how substitutions and variations will be approved. Keep a running forecast of final cost, not just a record of money already sent.
For example, an approved extra window changes more than a purchase line: it may affect drawings, opening details, fitting and finishes. Ask for the full cost and programme effect before approving a change.
Questions to send with your quote request
- Which drawing revision and measured areas did you price?
- What is excluded, provisional or based on an allowance?
- Which named materials and systems are included?
- How long are prices valid, and who carries changes in material costs?
- What evidence supports each proposed payment milestone?
Next step: use our building quote comparison guide with at least two quotes for the same scope. Building remotely? Start with the diaspora building workflow.
Reviewed 21 September 2026. Unsupported national price ranges in the earlier version have been removed. The numerical comparison is explicitly hypothetical.
