The ISOTEC Group
Causes for moisture



Only if one knows the cause of
the moisture and/or mould damage,
is a successful renovation possible.

Where do mould and moist walls come from?

What is the actual cause for damp basements or moist stains and mould in the living space? The answer is complex because the moisture in buildings may have very different causes.

Moist walls through condensation or dilapidated masonry

Kitchen and bathrooms are typical places where condensation problems emerge. The steam which results from cooking and showering charges the air with humidity. If we do not discharge this humidity from the air promptly, a moist layer appears on the wall and mould may emerge.

Moist basements are normally caused for a different reason. Chipping plaster is a possible symptom for moisture penetrating the masonry laterally, through the area that is in direct contact with the ground. Another reason may be a leaky pipe. If moist stains appear in the living space above the basement, it is possible that moisture is ascending through capillaries (“soaking“) from the basement.

That is why it is important to analyze the damage before its renovation.

One of the reasons why our renovations are so successful and maintain the building dry is because we continuously train our staff in the technique of analyzing. Only a professional analysis allows the development of an appropriate strategy and a permanent and secure renovation.

1. Capillary ascending moisture

Capillary ascending moisture emerges from the absorption capacity of porous construction materials

Capillary ascending moisture emerges from the absorption capacity of porous construction materials. Moisture ascends through the connected pores of the construction material, working against gravity. Moisture may penetrate vertically as well well as horizontally. The proper method in case of capillary ascending moisture is the ISOTEC Horizontal Barrier.

2. Moisture through lateral penetration

Lateral moisture penetration of the masonry, through the ground, may be caused by soil water, slope water and retaining percolate water or groundwater.

The DIN 18195 norm "Bauwerksabdichtungen" (German norm regulating the protection of buildings against moisture and water) states three types of water exposure which may affect the area of the building in direct contact with the ground:

  • Soil water (capillary water, adhesive water) and non-retaining percolate water
  • retaining percolate water
  • pressing water

We treat lateral moisture penetration with the ISOTEC Exterior Sealing or the ISOTEC Interior Sealing.

3. Hygroscopic Moisture

Hygroscopic moisture emerges through the property of salts to absorb air humidity. Therefore, the salts contained in the masonry - in particular sulphates, chlorides and nitrates - may result in moisture penetration of the masonry.

The appropriate measure for the treatment of hygroscopic moisture is the ISOTEC Sealing Plaster. Before the application of the sealing plaster, the water penetration needs to be stopped (for example, through the ISOTEC Horizontal Barrier, the ISOTEC Interior Sealing or the ISOTEC Exterior Sealing).

4. Condensation

The prerequisite for the emergence of condensation is a difference in temperatures.

If, for example, the room temperature is at 20 degrees with a relative humidity of 50 percent and air sweeps over a wall with a surface of only 10 degrees, the air cools down. As a consequence, the relative humidity rises close to the surface, because cold air absorbs less steam than warm air.

To avoid the condensation of moisture on walls, they need to be insulated. For this purpose, we apply our ISOTEC Climate Board or the ISOTEC Interior Insulation. If mould has already infested the walls, it is important to eliminate the mould through specific measures (elimination of mould damage).

5. Exposure to driving rain

Exposure to driving rain

Driving rain may affect the exterior building envelope, if the moisture protection or rather the humidity balance of the façade does not work properly.

A façade always needs to be able to release more humidity through diffusion during a dry period than is has absorbed during the rain. A well-functioning façade also prevents rainwater from reaching the interior part of the exterior walls.

6. Water damage

Water damages evolve from unique incidents where a big quantity of water has penetrated the masonry within a relatively short time. This may be caused by water-bearing pipes or inundation. In such cases our ISOTEC Drying System will help.