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Everything You Need to Know About Condensation

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Everything You Need to Know About Condensation

By Ruth MacEachern

Product Manager

Mar 01, 2024

One in five UK homes have a problem with condensation.  While it may appear to be a minor issue of water droplets forming on windows during colder weather, condensation is the tip of the iceberg of damp and if it is not dealt with properly, it can lead to damage to your home and worsen a number of health conditions.

What is condensation?

Condensation occurs when warm, moist air comes into contact with a surface of a lower temperature (or air of a lower temperature). When the two different temperatures clash, the warm air loses its ability to hold moisture. This results in water vapour suspended in the air and the appearance of water on the surface.

What causes condensation?

Any activity that increases the amount of moisture in the air of your home contributes to condensation.  Cooking, drying clothes on radiators, and bathing all release significant amounts of water into the air which increases humidity and raises the risk of condensation forming.

Types of Condensation

There are several different types of condensation which are present in most homes.

Surface condensation

Surface condensation is the most common type of condensation and also the most visible.  It takes the form of droplets of water on windowpanes, cold wall surfaces and tiles.

Cold-bridge condensation

Cold Bridge Condensation is caused when moist air comes into contact with colder surfaces.  It is often seen at the base of walls and on the underside of your roof.  It is often mistaken for rising damp and if not treated can cause windowsills to rot.

Interstitial condensation

Interstitial condensation is often unnoticed.  It is caused when the moist air diffuses into a permeable material like insulation.  If the material is warm on one side and cold on the other, the moisture will be deposited in liquid form and become trapped in the insulation where it can quickly support the development of mould.

Warm-front condensation

Warm front condensation is common in unoccupied houses which are not heated.  It often occurs I the winter during warmer periods and is caused by warm, moist air from outdoors being trapped in a cold building without other sources of moisture.

Reverse or Summer condensation

Reverse Condensation is common in the summer and often develops after heavy rain.  Heat from the sun can force water vapour from drying rain into the wall where it forms condensation on the outside of your insulation.

Radiation condensation

Radiation condensation is common on clear nights when the temperature drops quickly.  Radiation condensation forms on the underside of roofing material and then drips onto insulation in your loft where it can develop into damp and cause mould to grow and release spores into the air of your home.

Where does condensation form?

Condensation will form on any surface that is cooler than the ambient air but is most obvious to see on windows and tiles where it will form beads of water. 

Condensation also forms on surfaces where it can be absorbed, and this is what is most likely to lead to long term damp problems.  If the moisture from condensation is allowed to soak into walls and soft furnishings it becomes a breeding ground for mould and mildew.

What Causes Condensation?

Quite simply, any activity that releases moisture into the air contributes to condensation.  Bathing, cooking, and drying clothes all contribute significantly to the amount of condensation in your home.  Even breathing is a factor in condensation – the average person breathes more than 15,000 times per day releasing moisture into the air with every breath!

Condensation is worsened by poor ventilation – giving the moist air more time to come into contact with cold surfaces means more condensation can form.

Why is Condensation a Problem?

In the long term, condensation causes multiple issues in your home.  The most obvious result of condensation is damp.  You may see patches of black mould develop around windows or your ceilings.  Damp can cause a number of health problems for residents including worsening asthma and allergies due to the presence of dust mites and mould spores in the air.

In addition to health risks, long term damp can also cause damage to the fabric of your home, causing plaster to crumble away from walls and require expensive remedial work to fix.

Preventing condensation

Adequate ventilation is the most effective way to prevent condensation in your home.

Modern ventilation systems can protect your whole house from condensation by drawing fresh air into your property from outside and expelling moisture to reduce humidity.  Ventilation systems can range from a simple bathroom extractor fan through to a whole house system that ensures fresh air in all rooms.  Whole house ventilation systems are energy efficient and can be professionally fitted without damage to your property.

To find out how EnviroVent can help you improve indoor air quality and reduce condensation, please contact us today to book a free survey.


Need help with condensation, mould or damp problems?

One of our local experts will contact you to learn more about your problems, offer free expert advice and make recommendations for a permanent solution.

During the free survey we will

  • check Assess any condensation, damp or mould problems in your property
  • check Take readings of the relative humidity levels
  • check Identify any underlying problems and make recommendations for a permanent solution

Arrange a FREE Home Survey now