Concrete Roof vs Metal Roof Waterproofing in Ghana (2026 Comparison)
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Concrete Roof vs Metal Roof — Two Different Problems
Concrete roofs leak through the slab itself — cracks, porosity, failed coatings — so they need full-surface waterproofing. Metal roofs leak at discrete points — fixings, laps, flashings and box gutters — so they need targeted treatment. Applying a concrete solution to a metal roof wastes money; applying a metal solution to concrete leaves it leaking.
How Each Fails
| Concrete roof | Metal roof | |
|---|---|---|
| Primary failure | Cracking and porosity | Fixings, laps, gutters |
| Leak pattern | Diffuse, spreads | Point source, traceable |
| Treatment needed | Full-surface membrane | Targeted detail work |
| Thermal movement | Moderate | ⚠️ High — metal moves a lot |
| Corrosion risk | Reinforcement, if breached | ⚠️ Sheet itself, especially coastal |
| Condensation | Rare | ⚠️ Common underside |
| Typical cost | GHS 80–130 per m² | Priced by detail, not area |
Concrete Roofs — What Actually Goes Wrong
- Thermal cracking. A 20°C daily swing opens hairline cracks that widen over years.
- Porosity. Untreated concrete absorbs water directly. It re-evaporates inward, staining ceilings without any visible crack.
- Failed prior coating. Waterproof paint applied years ago, now chalking and peeling.
- Parapet junctions. Where slab meets upstand — the single most common concrete leak point.
- Ponding. Inadequate falls leave standing water that degrades any coating.
Solution: two-coat polyurethane liquid membrane across the whole surface, fleece-reinforced at every junction and penetration.
Metal Roofs — What Actually Goes Wrong
- Loosened screw fixings. Thermal cycling backs screws out; the washer perishes; water enters at every fixing.
- Sheet overlaps. Capillary action draws water up between sheets, especially on shallow pitches.
- Box gutters. The big one. Corrosion, failed joints and blocked outlets cause water to back up inside the building line.
- Flashings. At walls, chimneys and roof-lights.
- Underside condensation. Frequently mistaken for a leak. The fix is insulation and ventilation, not sealant.
Solution: butyl tape at laps and fixings; fleece-reinforced polyurethane through box gutters and flashings; corrosion treatment first.
Box Gutters — The Costliest Problem in Ghana
A metal box gutter runs inside the roof line. When it fails, water does not run down an external wall where you would see it — it discharges directly into the building, above the ceiling.
By the time a stain appears, water has usually been running into the structure for weeks. Ceilings, electrics and stored contents are affected before anyone knows.
Correct treatment is fleece-reinforced polyurethane across the full gutter width, carried up both upstands and over every joint and outlet. See our metal gutter case study.
Coastal Metal Roofs Need Extra Care
Within 15 km of the ocean — Tema, Sakumono, Prampram, Takoradi, Cape Coast — salt attacks metal roofs far faster than inland. Screw heads and cut edges corrode first. Waterproofing over active corrosion fails; the rust must be treated before any coating goes down.
Which Do You Have?
Fest Ghana Limited works on both. Free site assessment identifies the actual leak path — which on a metal roof is frequently several metres from where the water appears inside.
👉 Free Site Assessment · 0555 548 001