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How to avoid appearing of condensed water

27-01-2014  |  Administrator

Condensed water on the windows surface - cosmetic mistake or serious problem?

Undoubtedly the condensation of the windows in our home or office could be a serious problem. This is because, wherever it gathers more moisture, increases the risk of mold and bacteria. What can we do about it? Before answer let’s first try to understand where and why the condensed water appears. It appears where the hot air meets low temperature. The reasons for condensation of windows surface could be more than one. The main reason is not the windows itself but the way of its usage.

Reasons the condensed water appears

When the condensed water appears outside of the windows it’s a signal for an excellent heating and isolating properties of the windows. So, its appearance is not a problem, it is just a result of the weather conditions. 

When condensation forms between the windows that means that the space between it is not closed hermitically and it enters an air. The reason could be a crack in the windows, a defect in the windows, not good isolated windows. However, this could be a serious problem and we suggest such kind of windows to be changed. Condensed water inside the windows could have some other reasons – for example wrong installation or unequal windows. Usually, the real reason can be found only from professionals. But you should be careful because if the condense appeared in the windows become freezing this will be a serious damage in seal windows of in the construction of the windows.

Dangerous humidity

Common reason of condensation inside the windows surface (it means inside the house) is high humidity (in bathrooms, kitchens, etc.), for example drying of clothes in the room.

It can be avoid with right air circulation in the room. Heating source has to be installed UNDER the windows for good air flow. Common cause of condensation is internal blinds because they reduce the flow of air in the window. In cold days we suggest the blinds to be open.

Humidity in the interior serious impact the quality of our health. No matter the humidity standards tolerate the humidity between 30 and 70 % the perfect humidity is 40 %. Long-lasting high humidity creates perfect conditions for appearing bacteria and mold. Moreover - you know that humidity also affects the amount of energy for heating - to heat a room with 45-70 % humidity you will need 20 % more heating energy!


Appearing the condensed water on the windows could be avoided with right natural room ventilation or with good ventilation system. Ventilation “of fugue” is when you leave the windows open just a few centimeters. For long-lasting ventilation professionals don’t suggest this scheme, because it becomes too cold for the windows and this will increase the probability of mold appearing.

The best ventilation way is a full ventilation of the room with fully opened windows for just a few minutes (4-10 minutes). This way of ventilation will change the air in the room with just a little lost of energy. Another way for natural ventilation is when you open the windows and the doors together for a few minutes. (2-4 minutes). This way is suggested once every hour, especially weekends. If we make a ventilation the heating should be turned off or working with a minimum heating effect.

Micro-ventilation (when the window is open in its upper side with 10-15 centimeters) is not suggested by several reasons. It doesn’t provide the sufficient volume of air passing, reducing noise insulation and furthermore, if somebody stills something through the window most insurance companies does not pay anything.

One of the newest and most efficient systems to freshen the air in the room is ventilation valves. They work with a pressure difference between outside and inside air flow. The valve is fixed on the frame and it works with an automatic valve. The valves allow air exchange on 12-35 m3 for one hour.


Properties of the windows frame quality

 When choosing window, select one with a quality framework and at least triple glazing (or better). Double glazing is more sensitive to the condensed water but the triple has a high internal surface temperature. Profiles of the frame should allow bigger depth of glazing – at least 23 mm. Height of the frame should be at least 78 mm. Lower values will almost inevitably result in high dew and mold formation. You should be careful to the most important parameters - sealing both chambers between windows and window frame. The window frame needs 3 sealing chambers, not like the common 2 sealing chambers. Manufacturers often try to sell us windows which are suitable for housing, and for office or public buildings, since they have a lower humidity of the air or air-conditioning installed. So, please choose wisely.
And, of course, heating - it is a very valuable part of the above described process and again be stressed that it must be located under the window.