The verdict in three sentences
A B2B building materials marketplace in Cotonou linking 40 cement, rebar and aggregate suppliers with construction firms can work, provided it uses a 3 to 8% commission tuned by product family and reaches about 45 million FCFA of monthly volume to cover its costs. Kolonell's build budget sits between 4,000,000 and 7,000,000 FCFA (6,100 to 10,670 EUR) for a serious first version, up to 15,000,000 FCFA with integrated logistics. The main danger is not technical: it is disintermediation, when buyer and supplier deal directly after the first order.
A commission that fits construction margins
Cement is a very low-margin product: a supplier earning a few hundred francs per bag will never accept 8%. Rebar and finishing products can bear more. Aggregates (sand, gravel, laterite) sell by the truckload, and transport often costs more than the material.
Recommended commission grid, as 2026 order-of-magnitude figures for Benin:
| Family | Indicative market price | Suggested commission | Rationale |
|---|---|---|---|
| Cement (50 kg bag) | 5,000 to 6,000 FCFA per bag | 2 to 3% | Very thin supplier margin, large volumes |
| Rebar | 500,000 to 560,000 FCFA per tonne | 3 to 4% | Volatile prices, quote comparison is useful |
| Crushed gravel (15 to 20 m³ truck) | 300,000 to 450,000 FCFA per truck | 5 to 6% | Platform also arranges transport |
| Lagoon or quarry sand (truck) | 120,000 to 200,000 FCFA per truck | 5 to 6% | Fragmented, opaque market |
| Tiles, plumbing, electrical | Varies | 6 to 8% | Healthier margins, more SKUs |
| Equipment rental (mixer, scaffolding) | 15,000 to 60,000 FCFA per day | 8 to 10% | High-value service for the buyer |
The weighted average commission lands around 4 to 5%, which pushes the model toward volume rather than unit margin.
Must-have features
A materials marketplace does not look like a standard online shop. Buyers are site managers and purchasing teams who compare, negotiate and often pay on terms.
- Multi-supplier quotes: the buyer posts a list (200 bags of cement, 3 tonnes of 10 mm rebar, 2 trucks of gravel) and receives three compared offers within 24 h.
- Zone-based delivery: Cotonou, Abomey-Calavi, Porto-Novo, Sèmè-Podji, Ouidah, with transport rates by zone and truck type.
- Payment and payouts: collection by mobile money (MTN MoMo, Moov Money), bank transfer or certified cheque, then payout to the supplier after delivery confirmation, commission deducted.
- Digital delivery note signed by the site foreman, which triggers the payout.
- Supplier dashboard: orders, declared stock, amounts due.
Build budget on Kolonell's 2026 grid:
| Version | Scope | Kolonell budget | Timeline |
|---|---|---|---|
| Simple | Supplier catalogue, quote requests, orders, manual commission | 2,500,000 to 4,000,000 FCFA (3,810 to 6,100 EUR) | 8 to 10 weeks |
| Mid-complexity | Compared quotes, zone delivery, mobile money, automatic payouts | 4,000,000 to 7,000,000 FCFA (6,100 to 10,670 EUR) | 12 to 16 weeks |
| Complex | Mid + buyer credit, truck tracking, driver app, ratings | 7,000,000 to 15,000,000+ FCFA (10,670 to 22,870+ EUR) | 5 to 8 months |
| Maintenance | Fixes, updates, backups | 35,000 / 75,000 / 120,000 FCFA per month (53 / 114 / 183 EUR) | Ongoing |
Disintermediation: risk number one
A site manager who found a good rebar supplier on the platform will be tempted to call them directly next time. To limit this, the platform must offer value a direct deal cannot: delivery guarantee (refund if the truck never shows), 30-day buyer credit funded by the platform or a partner, standardised invoices for accounting, price history to justify purchases. Hiding phone numbers before ordering helps, but is never enough on its own.
Mini case study
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Rodrigue, an entrepreneur in Cotonou, is preparing his marketplace with 40 suppliers. Planned monthly costs: two sales reps and a logistics coordinator (900,000 FCFA), Premium maintenance (120,000 FCFA), field and WhatsApp marketing (300,000 FCFA), other (180,000 FCFA), so 1,500,000 FCFA per month.
- Weighted average commission: 4.8%. Mobile money and bank fees: about 1.3%. Net margin: 3.5% of volume.
- Break-even volume: 1,500,000 ÷ 0.035 = about 43,000,000 FCFA per month.
- That is, for instance, 25 active sites each buying 1,700,000 FCFA of materials a month.
- With a mid-complexity platform at 6,000,000 FCFA and volume reaching 60,000,000 FCFA a month after a year, the 2,100,000 FCFA monthly margin leaves 600,000 FCFA above costs: the investment is covered in 10 months.
FAQ
What volume is needed to break even?
With 1,500,000 FCFA of monthly costs and 3.5% net margin, about 43 million FCFA of orders a month. A leaner launch team lowers that threshold to 25 to 30 million.
Should we run logistics ourselves?
Not at first. Most platforms start with suppliers' own trucks and zone pricing, then add partner hauliers once volume passes 100 orders a month.
How do we collect and pay suppliers?
The buyer pays the platform by mobile money or transfer. Once the delivery note is signed, the platform pays out the amount minus commission, usually within 48 to 72 h.
Will large construction firms use it?
They often buy direct from cement plants. Construction SMEs, developers and self-builders are more realistic targets in year one.
Can we launch with fewer than 40 suppliers?
Yes. Fifteen reliable suppliers spread across product families are enough to test the model in three months before scaling.
Let's scope your project. We define your commission grid and payment and payout flow with you, then ship a first version you can test with suppliers within weeks. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
