What can I do if water condenses on windows or other building components?

Condensation, i.e. visible and palpable moisture on components such as windows, walls, or ceilings, is always a serious warning sign and should not be ignored under any circumstances. If the humidity in the building is so high that visible condensation forms, immediate action is required.

First, the resulting condensation should be removed immediately to prevent immediate damage to the affected components, such as moisture spots, material deformation, or mold growth. However, it is equally important to thoroughly investigate the cause in order to permanently resolve the problem.

 

The reasons for condensation

Condensation occurs, for example, after showering or while cooking. However, this is usually a normal process, as a lot of moisture enters the room air for a short period of time. As long as this does not happen too often—i.e., not several times a day and not over long periods of time—there is usually no cause for concern. In such cases, it is sufficient to ventilate the rooms adequately after these activities by opening the windows wide to quickly remove the humid air and reduce the humidity in the room.

The situation is different if condensation occurs without any apparent cause or on a permanent basis, for example when people are in the room or even when no one is there. This often indicates inadequate ventilation, which can lead to significant problems in the long term, such as permanent moisture, mold growth, or even structural damage. Regular bursts of ventilation are helpful in such cases, but cannot always be reliably implemented, especially at night or during longer periods of absence. Keeping a window open permanently is not recommended from an energy perspective, as this results in a significant loss of heating energy. It also increases the risk of burglary and can lead to renewed moisture problems and mold growth in the window reveal.

Another reason for problems with condensation is excessive airtightness in the building, which often occurs after energy-efficient renovations or in modern new buildings due to the use of high-quality insulation materials and airtight windows. In these cases, there is hardly any natural air exchange.

 

Measures against condensation on windows – this helps:

Installing a ventilation system is recommended for a healthy indoor climate. While simple solutions such as so-called free ventilation—targeted air vents in walls or windows—allow for a certain amount of air exchange, they are usually not sufficient. Mechanical ventilation systems are more effective, as they ensure controlled air exchange according to demand and can thus permanently prevent moisture problems.

1. 1. Regularly air out rooms: Open windows wide several times a day for a few minutes to quickly replace humid indoor air.
   2. Control humidity: Use a hygrometer to monitor the humidity in the room and ideally keep it below 60%.
   3. Don't forget to heat: Heat rooms sufficiently, as warm air can absorb more moisture than cold air.
   4. Do not place furniture directly against exterior walls or windows: this allows air to circulate better and prevents moisture from accumulating.
   5. Keep windows and window reveals clean and dry: wipe away condensation regularly to prevent mold growth.
   6. Ventilate immediately after showering, cooking, or drying laundry: remove moisture peaks in a targeted manner.
   7. Use ventilation systems: If the problem persists, consider installing a controlled mechanical ventilation system.
   8. Check seals and windows: Defective seals can lead to cold bridges and promote condensation.
   9. Use or retrofit air vents (e.g., in window frames) to enable basic air exchange.

 

These measures effectively reduce condensation on windows and significantly lower the risk of moisture damage and mold growth.

 

Working together on the condensation-free project

We are happy to advise you on any questions you may have about the various ventilation solutions.

📞 Phone: +49 30 362 001-91

📧 Email: planung@lunos.de