How to Prevent Window Condensation

Condensation is a very common problem and the excessive build up of moisture in a home is the most likely and major cause for this. “Sweating windows” for the most part are not the consequence of poor designs, faulty manufacturing or bad installation, but an issue that very many households encounter and that some have to deal with to some extent. Moisture problems are visible in many forms and can lead to other concerns such as wood rot, damp walls and mould and mildew build-up. Excessive condensation is thus a problem that should be dealt with and condensation should be limited to the extent that it is possible.


Condensation is the dampness formed when moisture in the air hits a cold surface and ‘condenses’ into liquid water. Air collects moisture from a huge array of sources such as our exhalations to the simple evaporation from water sources. Furthermore, activities that require the use of hot water – such as showers, cooking or washing clothes – considerably add to moist air. On a cold night in particular, as the windows get extremely cool, condensation is unavoidable. Some condensation is very normal and expected, but when wood begins to rot, water drips despite there being no leaks or a build of mould is seen, the levels of condensation are a problem.

How to prevent condensation

There are several things the inhabitants of a house can do to significantly limit the condensation that occurs, many of which cost nothing. Firstly, and perhaps quite obviously, reducing the amount of water vapour produced can be very beneficial. Drying clothes outdoors when possible, ensuring cooking pan lids are and that kettles are not left boiling for unnecessary time can all help. Certain types of heaters such as paraffin heaters can create lots of water vapour so these should be avoided.

Another way to reduce condensation problems is to keep the vapour contained within the bathroom or kitchen. By closing doors when cooking or showering, moisture is kept in a few rooms instead of spreading to the whole house. Then by ensuring these rooms are suitably ventilated by keeping a small window open or turning on the extractor fan, condensation will be limited. One of the best and sure fire ways of reducing condensation is through appropriate ventilation. Allowing the warm, high moisture air out of the house whilst letting cooler, lower moisture air in will help significantly.

Another route to reducing condensation takes a different kind of approach. Instead of reducing the amount of moisture that could condense on cold surfaces, limiting the cold surfaces can be equally effective. By keeping the home warm during the colder seasons, there will be less chance for moist air to condense. It is important not to heat the house using paraffin or portable gas heaters as these generate lots of water vapour, as mentioned above. Furthermore, the heating of a house is most effective when done at a low level but over a long period of time (as opposed to for a few short, but hotter, spells) to ensure the windows are always slightly warmed.