How to build a realistic schedule in Guinea and Sierra Leone: which activities are weather-critical, what continues under cover, site drainage and access, and how to read a bidder's programme.
In much of coastal West Africa the year has two shapes, not twelve equal months. There is a dry period in which earth can be moved, foundations poured and roofs closed, and a wet period in which some of that work becomes slow, expensive or impossible. A programme that does not show this distinction is not a programme; it is a wish.
This guide sets out how a realistic schedule is built, and how an employer can tell a serious one from an optimistic one.
The first question is not "how many months" but "what must be finished before the rains". Work backwards from that.
Weather-critical activities — the ones that should sit in the dry period wherever possible:
Activities that continue through the rains once the building is closed:
The single most valuable milestone in a tropical programme is therefore *building watertight*. Everything before it is exposed to weather; everything after it is largely protected. A good programme names that date explicitly and defends it.
Wet-season productivity depends on decisions made months earlier:
These items belong in the preliminaries budget as named lines. When they are missing from a bid, the bid is not cheaper — it is incomplete.
Concrete work does not stop entirely, but it changes:
Large exposed pours are best avoided; smaller, protected pours keep progress moving.
Output per worker falls in heavy rain even for sheltered activities, because access, material movement and supervision all slow. Realistic programmes apply a productivity factor to wet-season months rather than assuming a flat rate across the year. They also plan crew sizes to match: a workforce sized for dry-season earthworks has nothing to do in a downpour, and paying for idle time is a common hidden cost.
Shipping and clearance are not weather-proof either. Inland roads degrade, port congestion varies, and a delivery that arrives during the worst weeks may sit undelivered. Long-lead items intended for the dry-season push should arrive with margin — before the rains, not during them.
Ask for these five things:
1. A clearly marked wet-season band across the bar chart
2. The date the building is planned to be watertight
3. The list of activities designated weather-critical
4. The temporary works plan for drainage, access and storage
5. The productivity assumption applied to wet-season months
A contractor who can produce all five has planned the project. A contractor who produces a smooth bar chart with no seasonal markings has priced a building somewhere else.
Weather delay is foreseeable in a region with a defined rainy season, which is why contracts usually treat exceptional weather differently from ordinary seasonal rain. Agree at signature what counts as exceptional, how it is evidenced, and what relief follows. This single clause prevents a large share of the disputes that arise in the second year of a project.
Both countries have a pronounced wet season in the middle of the year and a drier period around the turn of the year, with the wettest months concentrated in the middle of the wet period. Local variation matters, so a programme should be built against site-specific data rather than a general rule.
No. Work that can be sheltered continues, and a well-sequenced project uses the wet months for internal trades. What stops is unprotected external work — which is why the watertight milestone dominates the schedule.
Rather than a blanket allowance, apply reduced productivity to wet-season months for the activities affected and keep weather-critical work out of them. That produces a defensible programme instead of an arbitrary buffer.
It can still succeed, but the sequence changes: the early months go into temporary works, drainage, access and procurement, so that the first dry period is used at full capacity. Recognising this at the start is far better than discovering it in month three.