Moisture damage

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Under a moisture damage is defined as a direct and indirect structural damage at one building or buildings caused by moisture. This can either be the result of external weather conditions , soil moisture or condensation .

A damage that z. B. caused by a burst pipe or a flood, however, is called water damage .

causes

In buildings, moisture can accumulate in different places and for different reasons:

  • External causes: Weather over roof coverings and wall sealing, rising and penetrating moisture in the masonry - countermeasures exist in all these cases in the professional structural sealing of the corresponding parts of the building.
  • Internal causes: Air humidity in buildings condenses in colder places in the building ( condensation moisture )

Planning deficiencies and construction defects

The planning deficiencies include incorrectly constructed details of the building envelope , e.g. B. in the area of ​​basement and roof seals, joints and connections but also thermal bridges (roller shutter boxes, concrete parts penetrating the wall or iron, faults in the thermal insulation ). However, improper or sloppy execution or the use of unsuitable building materials, i.e. construction defects , are just as often the cause.

Previous damage to the building

Even minor damage to the building, such as B. missing or defective weather protection, for example in the form of roof tiles (roof shingles) and defective rain gutters cause moisture to penetrate. In the area in contact with the ground, there are usually cracks in the outer walls that can arise from subsidence.

Weather and soil moisture

The above-ground parts of structures and buildings are constantly exposed to the weather. The influence of wind , rain and snow can cause moisture to penetrate the building envelope and no longer be able to escape.

Components in contact with the ground, on the other hand, come into contact with soil moisture . Here, the ingress of seepage water , groundwater or backwater is the most common cause of damage.

  • Water (stratified water ) penetrating laterally in the ground into cellar walls can, often a problem in buildings on a slope, penetrate the masonry after heavy rainfall.
  • Groundwater that reaches down to the cellar (pressing water) is another source of damp walls.

Capillary effects in the masonry and incorrect horizontal barriers can then lead to moisture penetration over several floors.

In some locations, the morning dew can also cause moisture damage if it occurs frequently and severely. Facades with a thermal insulation composite system , wooden cladding of the eaves or the roof box as well as unprotected metal surfaces and mobile electronics devices are particularly at risk .

Condensation of humidity

Depending on the temperature , the air can store different amounts of moisture in the form of water vapor. If the air temperature falls, the absorption capacity of the air also diminishes. The excess water vapor then condenses and settles as moisture on cool surfaces. Such cooling also takes place locally, for example on window panes, outer walls, edges and corners as well as thermal bridges.

The reasons for the high humidity during and shortly after the construction phase lie in the building materials used and later mainly in the use of the building.

In solid construction , a lot of excess water is required in order to be able to process building materials such as concrete, mortar and plaster. The construction timbers used today also have a high level of inherent moisture during installation. This moisture takes time to escape from the building. But since it is uneconomical to leave new buildings vacant for a long time, they go straight to use.

During use, there is constantly new humidity z. B. cooking, showering, cleaning and breathing air from the residents.

To make matters worse, the building envelope in modern new buildings is particularly well sealed in order to be able to save energy through low air exchange.

consequences

In addition to minor optical damage such as mold stains or discoloration, moisture can lead to serious structural damage that endangers stability. These are often slowly progressing processes that take place in secret. Mortar and concrete are leached out, flaking due to corrosion of the reinforcement or frost damage can occur, steel structures rust, and wood structures are caused by rot and deformations due to swelling.

Consequential damage such as mold , bacterial infestation and dry rot (notifiable) lead to health problems for residents due to e.g. B. Allergies or respiratory infections . This can lead to the building becoming uninhabitable.

Redevelopment

It is important to determine the exact cause and location of the damage. Especially in the case of damage caused by penetrating moisture, the cause can be far from the actual damage pattern, e.g. B. with a defective flat roof or basement waterproofing. If the cause cannot be determined immediately and without any doubt, it is advisable to seek advice from an independent specialist, as renovation often results in considerable costs.

To repair a leak, the damaged area is exposed from the outside, if necessary repaired and re-sealed. In the area of ​​building joints and basements, this can be done e.g. B. be impossible due to neighboring buildings. Then the damage has to be repaired from the inside of the building. To this end, the private sector has developed a large number of procedures, some of which are controversial.

It becomes difficult and time-consuming when planning or construction defects lead to damage that is due to the construction of the building (e.g. thermal bridge). In any case, an expert must be commissioned here.

Measures on the indoor climate

Regular ventilation is a preventive measure or emergency remedy if there are moisture problems. Short-term intermittent ventilation (with the window fully open) is to be given priority over continuous ventilation (tilted windows) in the cold season in order not to cool down the already cold surfaces any further. When the air volume is exchanged and cooled, without cooling the surfaces, the air in the room warms up and absorbs moisture.

In the long term, an adapted room climate with a relative humidity between 40 and 60% should be aimed for. Air conditioning systems clear up the problem, provided they are properly installed and function correctly, otherwise they can themselves be the cause. Special air dehumidifiers (water separators) are maintenance-intensive: regular emptying is necessary.

See also

literature

  • Herbert K. Kalcher: Moisture damage in the house. Recognize causes - eliminate damage, Eberhard Blottner Verlag, 2009, ISBN 978-3-8936-7404-6 .
  • Joachim Schulz: Architecture of structural damage. 2nd edition, Springer Fachmedien, Wiesbaden 2012, ISBN 978-3-8348-1470-8 .

Individual evidence

  1. ↑ Jenny Schäfer, Christoph Trautmann, Ingrid Dill, Guido Fischer, Thomas Gabrio, Ingrid Groth, Udo Häckel, Wolfgang Lorenz, Karin Martin, Tina Miljanic, Regine Szewzyk, Ursula Weidner, Peter Kämpfer: Occurrence of actinomycetes in interiors. In: Hazardous substances - keeping the air clean. Vol. 69, Issue 9 (2009), ISSN  0949-8036 , pp. 335-341.

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