What causes condensation and how to solve it

Condensation is a common problem in many homes, which can cause cosmetic damage to your décor and furnishings, but also has the capability to cause structural damage to your property as well as health problems for your family.

The condensation process is often associated with poor ventilation in homes, particularly during winter or cooler weather. Warm air, often produced by home appliances, that is laden with moisture comes into contact with cold surfaces such as windows, mirrors and walls where it forms tiny droplets of water, known as condensation.

If left unchecked over a period of time, condensation can be troublesome and destructive.

What are the causes of condensation?

Although there are many causes of condensation, the most common include:


The heat produced by cooking appliances and the steam that rises from saucepans on the hob raise the temperature in the kitchen and, in open plan styles of property, surrounding rooms. Condensation may appear on windows, worktops and kitchen cabinets.

Drying clothes

During warm weather, when we can take advantage of a garden or balcony to dry our washing, the moisture that evaporates from damp clothes dissipates into the atmosphere; during wet or cold conditions when we dry indoors, the water vapour has nowhere to escape to, settling instead on the nearest cool surfaces. Even using a tumble drier that doesn’t have a condensing hose will emit up to four litres of moisture into the surrounding air!

Bathing and showering

The water vapour and steam produced by a shower or hot bath will create a lot of moisture which you’ll notice most prominently on windows, mirrors, tiled surfaces and sanitary ware.

How can I spot condensation?

Condensation is easy to spot when it forms of surface such as windows or mirrors, as they will mist over quickly. Windows are usually the first place you will notice it because the glass is cool. Single glazed windows tend to suffer from condensation more than double glazed units because the temperature of the glass is lower.

If the condensation problem is persistent, you may notice other signs in the home including:

  • Dampness on the surface of walls particularly around windows, behind or inside furniture and in the corners of rooms – in fact, anywhere where the airflow is reduced.
  • Black dots or marks forming on windows frames and along the inner seal when the frame and glass meet.
  • Mould, which is often speckled, black and patchy, appearing on walls and soft furnishings.
  • Peeling or bubbling wallpaper that may be easy to pull away from the wall. The plaster underneath may also be soft or crumbly, indicating that damp has penetrated the surface.

What problems can condensation cause?

The presence of damp in your property is not necessarily a sign of a major structural problem in your home but problems caused by condensation should not be ignored!

Persistent condensation can be unsightly as wallpaper peels away and discolours, mould forms in patches on hard and soft surfaces and the window frames turn black. However, apart from the obvious unpleasantness of having to live in a home that, cosmetically, looks unappealing, there are potential risks to the structure of your house and the health of yourself and your family if the problems caused by condensation are not addressed.

Mould caused by condensation is proven to cause or exacerbate breathing problems such as asthma. Mould releases spores into the air that, if inhaled regularly, can cause wheezing, coughing, nasal congestion and tightness in the chest. Long-term exposure to mould spores is known to be a cause of chronic breathing illnesses.

Dampness that is caused by condensation can also cause damage to your property. Wooden window frames, for example, can become infested with rot, softening and crumbling over time, while plaster will crumble if exposed to dampness for too long. Condensation can also form in hidden places, such as under floorboards, increasing the possibility of fungal decay setting in.

How can I reduce condensation in my home?

Reducing condensation is the most important step you can take to eliminate many of the problems that occur when moisture in the air settles on surfaces around your home. Ceasing the activities that tend to cause the problem – cooking and washing – clearly isn’t practical so steps must be taken to reduce the amount of moisture that is in the air, particularly in hotspots that are more prone to being affected.


A dehumidifier can be purchased from most DIY shops and can be effective in eliminating some of the condensation in small areas around the home. The units, which are inexpensive to run, draw moisture from the air and store it until you can empty it down the sink. Although a dehumidifier won’t solve a major condensation problem, it can help to reduce it.

Double Glazed Windows

Replacing single glazed windows, if money and building regulations allow, with modern double glazed units can be effective. It may only be necessary in certain rooms but, in older or historic properties, planning and building regulations may restrict the type of replacement windows that you can install.


Improving ventilation in problem areas is key. Modern homes tend to be very airtight which affects the natural flow of air and can contribute to the condensation process. Opening the windows in the bathroom or kitchen will instantly improve the airflow and reduce the temperature of the air, meaning condensation is less likely to form.

Extractor Fans

Extractor fans, particularly in bathrooms and kitchens, can significantly reduce condensation and are cost-effective to run, but ensure that you source one that is suitable for the size of the room. Most fans can be set to operate for a specified period to remove residual moisture from the air, even after you have finished cooking or showering. Also, always keep the door shut when the extractor fan is operating.

Trickle vents

Trickle vents in windows can be effective in supplying fresh air to this part of the room while more costly but effective solutions can also be installed, such as a heat-recovery ventilation unit that will extract damp air from your property and replace it with warmed, fresh air.