Prevention of condensation

This is the second article in a series on condensation from Daniel James Construction Services, experts in the diagnosis, treatment and prevention of dampness in buildings.

Why does condensation form?

Condensation forms when air containing moisture meets a surface at or below dew point. At lower temperatures, the capacity for air to hold water is diminished and vapour turns to liquid.

In the home it’s common to find condensation on cooler surfaces like glass and mirrors and in corners or behind furniture where air circulation is low. This is particularly common in the UK between the months of April and October when heating systems are in use during the cooler hours of the day.

Left unchecked, condensation can damage decorations, encourage the growth of mould which can be harmful to health, and in serious cases, cause structural decay.

The generation of moisture in the home is largely unavoidable with everyday activities like drying clothes, showering and cooking releasing large amounts of water vapour into the air. Given the nature of the activities that cause condensation it comes as no surprise that kitchens, bathrooms and utility rooms are the main areas in which we look to control condensation.

Average home daily moisture production:

Drying & Washing Clothes 6 Litres
Cooking & Boiling Kettles 3 Litres
Bathing & Showering 1 Litre

Tips for Condensation Prevention

Prevention is better than cure and there are steps you can take in the home to minimise moisture generation and therefore prevent or reduce the likelihood of condensation.

Turn on extractor fans when cooking, showering or bathing to ensure the moisture generated is removed from the air. Where possible, keep bathroom and kitchen doors shut to prevent the escape of moisture into other rooms.

Avoid fluctuations in temperature by consistently heating all rooms in the home.

Insulate walls and ceilings to prevent cold areas where the temperature may fall below dew point and cause condensation to form.

Dry clothes outside whenever possible. Using tumble driers or hanging clothes over radiators creates significant water vapour through the process of evaporation. When using tumble driers, always ensure external ventilation of the appliance. Additional ventilation is almost always required where tumble driers are present, even in the case of condenser driers which extract some but by no means all of the water removed from clothes.

Keeps lids on pots and pans when cooking to limit the amount of moisture released into the air.

Leave a gap between walls and furniture to allow air flow.

Controlling Condensation with Ventilation

The most effective way to tackle condensation once it occurs is to install adequate ventilation, reducing humidity by allowing drier air from outside a building in, and the more humid air inside to escape. The result is a reduction of the vapour pressure differential, a measure of the difference between internal and external vapour pressure which is the aim of ventilation systems and an indicator that can be used to determine their effectiveness.

Opening windows is a great way to ventilate buildings but isn’t really an option in the colder months when we’re trying to keep heat in. Fortunately, there are many relatively low-cost ventilation options that can be installed to control condensation in rooms most affected.

Mechanical Extractor Fans for Condensation Control

The most frequently used methods for combatting condensation in the home involve mechanical extraction of some form, with extractor fans being the most common.

There are many factors to consider when selecting an extractor fan, with placement, switching and extraction rate all important considerations.

Our expert team is on hand to provide advice and on all aspects of damp and ventilation issues including extractor fan selection and other methods of condensation control. Contact us on 0208 132 8112 or email for more information.

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