Cement blocks absorb water easily because of their microscopic pores. During the rainy season, bare walls soak in rainwater and stay damp for days. With the high humidity in the air, these walls don’t dry out quickly, creating an ideal breeding ground for mould.
Why Bare Cement Block Walls Are Vulnerable to Mould
In The Gambia and other humid climates, it’s common to see houses built with cement blocks left bare — without plaster, render, or paint. While this might seem like a way to save money during construction, leaving cement block walls exposed makes them highly vulnerable to mould, algae, and dampness.
Cement Blocks Are Naturally Porous
Dirt and Dust Build-Up
Bare blocks have a rough, dusty texture that traps dirt. When rainwater runs down the wall, it mixes with this dirt and forms streaks where algae and mould thrive.
Temperature Swings Cause Cracks
The Gambian sun heats walls during the day, while cooler nights cause them to contract. This daily cycle leads to hairline cracks that let in even more moisture.
Long-Term Structural Damage
Constant moisture doesn’t just encourage mould — it slowly weakens the cement, leading to erosion and spalling over time.
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Practical Tip
Always budget for plastering or rendering, even if it means delaying the final finish. A small investment up front saves you years of repair costs.