How Condensation Causes Mould
By Ruth MacEachern
Product Manager
Dec 12, 2024
Condensation is a common issue in many homes, particularly during the colder months. It forms when warm, moist air meets cold surfaces such as windows, walls, or ceilings.
As the moisture is released from the cooling air, it turns into droplets of water droplets which can soak into porous surfaces like wood or plaster and create the conditions where mould spores can start to grow.
How condensation causes mould
Condensation forms because the amount of water vapour that can be carried in the air drops as the air cools. In your home, areas around windows and exterior walls are colder than the rest of the room, so as the air circulates, it releases that water vapour, and it forms droplets of water on the surface that can soak through and create damp patches.
The microscopic spores that mould grows from are always present in the air, but until they find the conditions that will allow them to start growing, they remain dormant.
Mould thrives in damp, humid conditions. The damp patches caused by condensation provide an ideal environment for mould to grow. Over time, if the moisture problem is not addressed, mould can spread and cause damage to surfaces and potential health issues for people with allergies or weaker immune system such as children and the elderly.
Where does the moisture that forms condensation come from?
The activities of daily life release surprising amounts of water vapour into the air of your home, and if this is not removed through ventilation, it can lead to condensation and mould problems. Some of the most common sources of humidity include:
Cooking, especially boiling water on the hob. You can reduce the amount of steam released into the air by keeping a lid on your pans and ensuring that the extractor hood above your stove is used.
Hot showers and baths produce steam, increasing humidity in bathrooms. By using an extractor fan when taking a shower or bath, you can reduce the amount of water vapour that escapes from the bathroom into the rest of your home.
Drying clothes and towels indoors on radiators or using a tumble dryer without proper ventilation can add significant moisture to the air. If you must dry clothes indoors, ensure that you leave a window open to allow air to circulate and leave the door of the room where you are drying clothes shut.
Reducing humidity levels helps prevent condensation and mould
The most effective way of preventing condensation and mould growth is through improving the ventilation in your home.
Extractor fans in rooms with a source of moisture such as a bathroom or kitchen removes much of the water vapour before it has a chance to spread. Modern extractor fans such as the EnviroVent Cyclone 8 feature a humidity sensor that detects the amount of water vapour present in the air and adjusts power levels to remove it more quickly.
Whole house ventilation such as EnviroVent ATMOS, which is a Positive Input Ventilation System (PIV) draw outdoor air into your home from outside to displace the humid air. These systems also have the benefit of improving the circulation of air in the home, which evens out temperatures and prevents condensation away from a source of water vapour.
Get help with condensation and mould today
Mould in your home can be damaging to your health and cleaning it will only get rid of the problem temporarily. Book a free home survey from one of our local ventilation experts. They will visit your property, identify the sources of condensation, and provide you with advice about the best way to stop it. Enter your postcode below to find a specialist near you.
