Understanding humidity in walls: causes and solutions

What is humidity in walls?

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Humidity in walls is a common phenomenon that can affect the structure of a building and the quality of indoor air. It occurs in the form of stains, molds, saltpeter or paint peeling.

Three main causes are identified:

• The capillary lifts : water from the ground rises into porous materials such as brick or concrete.
  
  
• The infiltrations : caused by cracks, damaged joints or damaged roofs.
  
  
• Condensation : linked to temperature variations and poor ventilation.
  
  

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Condensation and humidity in walls: a frequent phenomenon

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Unlike capillaries or infiltrations that require technical intervention, condensation can often be prevented on a daily basis.

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Why does condensation form on walls?

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Let's take a cold room at 9°C, in which the heating is turned on up to 20°C. The walls, by thermal inertia, remain colder than the ambient air. This difference creates a dew point: the water vapor in the hot air condenses when it hits the cold wall. This phenomenon occurs very often in second homes.

Condensation can also form on walls in shower rooms and laundry rooms: hot water from showers or laundry evaporates and then condenses on colder walls.

This phenomenon is all the more frequent in poorly ventilated areas, with little insulation or without a vapor barrier.

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How to avoid humidity in the walls?

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Here are some simple things you can do to avoid condensation on the walls:

• Ventilate rooms every day, especially after cooking or showering
  
  
• Maintain a homogeneous temperature in the room
  
  
• Use a humidity tester or humidity sensor to monitor changes
  
  
• Avoid furniture stuck to the walls, especially in cold areas
  
  
• Install the ribbon Air Sponge in rooms subject to condensation
  
  

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Going further: monitoring and controlling indoor humidity

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Investing in a professional moisture meter or humidity controller helps prevent humidity problems before they become visible. These devices measure relative humidity and may indicate a risk of condensation.

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