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How does water and moisture affect building health

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In the previous article, we have established that humidity plays a vital role in causing condensation that is commonly attributed to damage to building material.

Now we are going to discuss how water in buildings affects the building material detrimentally causing damage if it is not managed.

The source of water in buildings

The main source of water has to be rain in a tropical and equatorial climate. Malaysia on average receives 2800mm of rain annually, and it rains more than 200 days a year. The volume of rain has influenced the design of roofs in vernacular architecture with high pitch roofs with large overhangs to channel the water away from the walls.

Image of Kampung House in Malaysia

The damage from rain onto buildings are leaking roofs and gutters, insufficient flashing, inadequate overhangs, incorrect or poor specification of plastering, bridging of rainwater from poorly formed door and window sills, and wind-driven rain that enters buildings through gaps between doors and windows.

Internal parts of a building are generally not designed to have durability against excessive moisture. Building materials and elements that are supposed to be the protective barrier like the roof have to play its role effectively and be durable throughout its intended design life.

Another important source of water that potentially can cause water damage is pipe leaks and clogs. Water supply pipe that carries fresh water and soiled water can potentially leak either from poorly formed joints, pressure or impact damage, or deteriorate due to fatigue. Leaks are only visible when the effect is severe enough that building occupants notice dampness or discolouration spots forming on unlikely surfaces such as in the middle of a wall.

Water can potentially travel from the ground and up the wall in a phenomenon called rising damp. Bricks, plastering and concrete are porous materials microscopically and capillary action may cause dampness to rise from within the ground and evaporates through the wall capillary where in the process, causes damage to brickwall due to saturation, and any materials in contact with the brickwall such as timber causing excessive moisture absorption that leads to decay.

Apart from the environmental forces described above, human activity can also potentially cause water damage to building elements. Typical human activities such as cooking, washing, drying clothes, even breathing, introduces moisture within the building envelope. What is important is to be able to provide enough ventilation to allow moisture to evaporate out efficiently from the building. This includes splash and spillage that must be dried up quickly before they cause damage to the building and its internal elements.

Building cut away diagram

© Universiti Malaya
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Building Pathology: The Science Behind Why Buildings Fail

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