Is moisture on windows dangerous

Is moisture on windows dangerous

By Ruth MacEachern

Product Manager

At this time of year, waking up to see water streaming down the inside of your windows and forming pools of water on your windowsills can become a daily occurrence that may make you worried.  In isolation, the presence of this moisture is harmless, but if you do not address the root cause of wet windows in the morning, it can lead to bigger problems with damp and mould in your home.

What Causes Condensation on Bedroom Windows

The sight of condensation on your bedroom windows in the morning is most common on colder days.  It tends to be more obvious during the autumn and winter months because at those times, the outside air is cooler, and when warm, moisture rich indoor air comes into contact with your windows, it can no longer hold as much water, which forms into droplets on the surface of the glass.

The source of the moisture in the air that forms the condensation depends on the room you are in.  In bathrooms and kitchens, the cause is usually quite obvious - bathing or cooking, however in a bedroom, the moisture that forms overnight is actually the water vapour that we breathe out in our sleep!

On an average night, an average person will release around 40g of moisture into the air as they breathe.  Over the course of an 8-hour sleep, with two people in the room this means around 640ml of water vapour is added to the air – more than a pint!

The amount of moisture that can be held by the air is dependent on temperature.  At 20C, air can hold about 17g of water per cubic metre, however at 10C, this amount falls to just 9.4g.  Assuming that you have a bedroom, which is 2.5mx4mx5m, this means that you have fifty cubic metres of space, which would give a capacity of about 850g or moisture in the air.  As the water vapour that is breathed out as we sleep is added to the existing moisture content of the air, our breathing can quickly overload the capacity of the air in the room to carry moisture, and as a result, the liquid will condense out.  This is most obvious in the cooler parts of the room such as close to windows, where the lower temperature means less moisture capacity in the air.

Is water on bedroom windows a problem?

Condensation on your windows isn’t necessarily a problem, but if it is not addressed, that condensation can lead to damp soaking into the surrounding walls and window frames that may cause damage to plaster work and lead to mould growth that can be harmful to your health.

Condensation on your bedroom windows is usually a symptom of poor airflow in your bedroom.  The trapped air is becoming saturated because there is nowhere for it to go.

Improving the ventilation in your bedroom is the best way to stop water from forming on your windows overnight.

Find out More

To learn more about the best way of preventing condensation on your windows from developing into a more serious damp or mould problem, please contact one of our local ventilation specialists.  They will be able to carry out a free home survey that will identify the root cause of any condensation problems that you have and recommend an appropriate solution.