Most people begin a duplex project with a single question: “How much will it cost?” The honest answer is that there is no single figure. The cost of a duplex depends on its size, design, finishing level, location, material prices at the time of building, and the condition of the site. What you can do is understand how the budget is distributed, so that every naira is planned before construction begins.
This article explains the major cost stages of a duplex and the factors that move your budget up or down.
Where the Money Goes: Typical Cost Distribution
The ranges below are indicative only. Actual proportions vary from project to project, so use them to understand priorities, not as fixed quotations.
StageIndicative share of total costSite preparation and foundation (substructure)15% to 20%Walls, columns, beams and slabs (superstructure)25% to 30%Roofing10% to 15%Plumbing and electrical installation10% to 15%Finishing (plastering, tiling, ceilings, painting, doors, windows)25% to 30%External works (fencing, paving, drainage)5% to 10%
1. Site Preparation and Foundation
This stage covers clearing, excavation, setting out and the foundation itself. Cost rises on sloped plots, poor soils and sites that need extra drainage or retaining works. A land survey and proper structural design at this point prevent expensive corrections later.
2. Superstructure
Blockwork, columns, beams and floor slabs form the largest structural expense in a duplex because it has two floors. The quality of reinforcement, concrete and blocks directly affects durability, so this is the wrong place to cut corners.
3. Roofing
The cost depends on roof design, structure and the roofing sheets or tiles selected. Complex roof shapes cost more in both materials and labour.
4. Plumbing and Electrical Installation
A duplex has more bathrooms, more circuits and more pipework than a bungalow. Plan these early, because changing layouts after plastering is costly.
5. Finishing
Finishing is where budgets are most often exceeded. Tiles, kitchen cabinets, ceilings, doors, windows, paint and fittings can range from basic to premium. Decide your finishing standard before construction starts, and price it separately.
6. External Works
Fencing, gates, paving, drainage and landscaping are frequently left out of the original budget. They are not optional: a building without proper drainage and boundary works is incomplete. See our landscaping and exterior services.
Costs Many First-Time Builders Overlook
- Survey, soil investigation and professional design fees
- Approval and permit fees
- Borehole, water tank and pumping system
- Generator or solar installation
- Site security and temporary storage of materials
- A contingency allowance for price increases
A sensible practice is to set aside a contingency of around 10% of your budget for unforeseen changes.
How to Keep Your Budget Under Control
- Start with a complete design. Changing a design during construction is one of the most common causes of overspending.
- Request a Bill of Quantities. A BOQ lists every material and work item, so quotations can be compared fairly.
- Fix your finishing standard early.
- Supervise the work. Material wastage and poor workmanship quietly increase cost. Professional project management and supervision helps protect your budget.
- Choose a design that fits your plot. Browse our duplex plans, including the 5-bedroom duplex on a 60 x 100 ft plot.
For bungalow costs, see our guide to bungalow plans you can build to finishing for ?35 to ?80 million.
Frequently Asked Questions
Can I give you my budget and have you design to it?
Yes. Share your budget, plot size and requirements, and our architectural design team will recommend a suitable design.
How long does a duplex project take?
Most residential projects take between 6 and 14 months from design to completion, depending on scope and size.
Can the project be built in phases?
Yes, but phasing must be planned from the design stage so that completed sections are protected while later phases continue.
Get a Clear Estimate
Every project is different. Request a free consultation and we will discuss your plot, requirements and budget, or chat with us on WhatsApp. You can also ask for our free cost estimate guide for duplexes and bungalows.
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