Condensation is the most common cause of mould growth in modern properties. Air in your home holds moisture, the warmer the air the more moisture it can hold. When warm, moist air comes into contact with a cold surface (for example a glass window pane / external wall) the air can no longer hold the moisture and it turns into a liquid, in the form of water droplets. The water then helps to germinate mould spores, causing them to grow.

How to prevent condensation

The primary cause of condensation is lack of ventilation and improper use of heating. When moist air builds up inside your property it is important to remove it by means of ventilation. This will allow fresh, dry air to circulate in your home.

Your central heating must be used in conjunction with ventilation, especially in colder winter months to help warm cold external walls and prevent cold spots. This will stop excess moisture from turning into a liquid when it comes into contact with a cold surface.


  • Remove excess moisture by opening a window at opposite ends of the property, especially after bathing or cooking. This is known as ‘Cross Ventilation’
  • Keep trickle vents open on windows
  • Do not block air bricks, passive vents or extraction fans
  • Avoid opening windows on damp or humid days as this can introduce more moisture back into your home. It is best to open windows on dry days.
  • Keep Central Heating low but consistent. We recommend setting a constant temperature between 16 and 20 degrees Celsius and boosting when required. (this will help get warmth into your walls and reduce cold spots)
  • Ensure radiators are kept clear, this will allow heat to circulate properly
  • Do not put your heating on high for short periods of time and then turn it off completely. (this creates warm air but does not warm walls which leads to cold spots & condensation)
  • Ensure the thermostatic radiator valves are open and each one is on the same setting. This will ensure an even heat throughout your home.

Avoid Creating Cold Spots

Keep furniture away from cold or external walls. Solid objects located against cold walls such as cupboards, beds, headboards or even sofas can restrict air flow and create a cold spot on the wall. This creates the perfect conditions for condensation to form, leading to mould growth.

  • Try keeping any solid objects at least 50cm away from cold or external walls
  • Avoid over filling rooms with furniture or belongings to increase airflow

Reducing moisture

Along with proper use of heating & ventilation, a key part of preventing condensation is reducing the amount of moisture we create at home.

Moisture is created by day to day activities such as bathing, cooking, boiling water, drying wet laundry or even breathing! The average person can add up to 9 litres of moisture in the air per day.

For modern households these are things we cannot live without but what is important is how to reduce the moisture created by these activities. Don’t worry we are not going to ask you to stop breathing, luckily there are more simple solutions to reduce the moisture we create, such as:

  • Avoid drying wet washing on radiators. If you do not have access to an outdoor area please use an airier placed in a warm, well ventilated room that is shut off from the rest of the property
  • When running a bath try filling with cold water first: This can reduce moisture created by 80%
  • Always ventilate an area by opening a window or using an extraction fan (if available) when creating excess moisture such as cooking or bathing. Please ensure the room is left well ventilated for a while after you are finished to help remove all of the moisture
  • Shut internal doors to rooms where excess moisture is being created. This will prevent the moisture from traveling into cold rooms and turning into condensation
  • Place damp crystals or mini dehumidifiers near windows and other areas that are common for condensation. They will help absorb any excess moisture that may not have escaped your home
  • Cover pots and pans when cooking
  • Wipe down any visible condensation or water as soon as possible. The longer water sits on a surface the more likely mould will grow.