Understanding humidity in walls: causes and solutions

​​Where does the moisture in the walls come from?

The presence of humidity in walls can have three distinct origins:

1. The capillary lifts

Water rises up from the ground through the porous materials in the wall. This phenomenon is structural and generally requires the intervention of a professional.

2. Water infiltrations

Cracks, watertightness defects or damage in the structure can allow rainwater or external humidity to pass through. Again, work is often essential.

3. Condensation

It is the most common cause in homes. It occurs when ambient water vapor encounters a surface that is colder than air, causing droplets to form on the wall.

Contrary to the first two causes, condensation can be reduced by simple daily actions.

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Why does condensation form on a wall?

Condensation is directly linked to temperature variations.
Let's take a common example:

• A room is cold (e.g. 9°C).
  
  
• The heating is switched on to reach 20°C.
  
  
• The air heats up quickly... but The wall stays cold longer.
  
  
• Warm, humid air touches this cold surface → it cools suddenly → the water in it condenses.
  
  

In other words:
The greater the contrast between the air temperature and the wall temperature, the greater the risk of condensation.

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A simplified explanation of the calculation

There are scientific formulas (saturated vapour pressure, relative humidity, etc.) to determine if the air contains more water than it can hold at a given temperature.
In the example provided, once the room is heated to 20°C with 50% relative humidity, the quantity of water in the air becomes greater than what the air can contain at the level of the wall remained at 9°C.
→ 🠒 Result: guaranteed condensation on the cold wall.

No need to go any further in the equations:
If humid air touches a cold wall, water settles.

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How to limit humidity caused by condensation?

Several simple actions can be used to reduce condensation in the walls:

• Ventilate regularly, especially after activities that generate steam (showering, cooking).
  
  
• Avoid thermal shocks by heating gradually.
  
  
• Improving airflow behind the furniture veneered on the walls.
  
  
• Stabilize the ambient humidity, to reduce the quantity of vapour likely to condense.
  
  

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Air Sponge: a passive solution to limit excess humidity

In rooms where humidity varies widely, controlling water vapor is essential to reduce condensation on cold walls.

Air Sponge works by adsorption thanks to its patented mesoporous material, which captures humidity when the level exceeds about 60%, then releases it naturally when the air dries up.
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Unlike conventional absorbers (salts, silica gel):

• It does not saturate permanently,
  
  
• does not require any replacement,
  
  
• does not consume electricity,
  
  
• and does not produce any waste.
  
  

Its adaptable format (tape, adhesive or magnetic depending on the configuration) allows it to be easily placed in areas subject to condensation, which contributes to stabilize the ambient humidity and to reduce the risk of droplets on cold walls.