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What is condensation?

Condensation happens when warm, wet air meets cold surfaces and can make things damp. Air always has a bit of wetness in it, like steam. When it’s warm, it can hold more wetness. But when it touches something cold, the wetness turns into little water drops, like when your cold drink makes the glass all wet.

This wetness can show up on cold places in your home, like windows or corners, and that can cause mould to grow. If the air is too wet for a long time, like when it’s really muggy outside, there’s a bigger chance of condensation and mould. To stop this, you can try to keep your home not too humid and make sure air can move around. See our additional advice about keeping your home warm and dry.

Why is it a problem? 

Excessive condensation can cause mould growth on walls, ceilings, furniture, clothes, and fabrics. It can also lead to decay of building materials such as wall plaster or woodwork and can ruin decorations.

How do you spot it? 

Common signs of condensation are:

  • Streaming windows and walls
  • Damp areas and mould can appear on walls, especially behind furniture and in corners
  • Wallpaper can start to peel
  • Speckles of black on the silicon sealant around windows and baths etc.
  • Mould growth starts to appear
  • Furniture and fabrics become prone to mould and mildew
  • You may also notice a musty smell

Where does the moisture come from? 

Water vapour is produced when carrying out everyday routines such as washing, cooking, drying clothes. Even just breathing releases moisture into the atmosphere.

An average family of four can produce 24 pints (14 litres) of water vapour in just 24 hours, and all that moisture must go somewhere. If this moisture is not ventilated to external air, then it will eventually condense back into a liquid and encourage mould growth.



Download our condensation information page here.