There is always moisture in the air even if you can’t see it. Air is really good at holding water vapour (otherwise known as humidity), however whether this becomes a problem depends on temperature.  

Condensation can happen when moisture laden air comes into contact with cold surfaces such as walls, windows, in loft spaces etc where it starts to cool and liquid water drops out as condensation. If condensation issues are not identified and action taken, problems with mildew and mould can occur.  

This leaflet provides advice on how to avoid condensation issues and where problems are found, how to remove mildew and mould. 

The humidity of air inside a house can be reduced by ventilation. Where air is not changing in a room or house, then the humidity increases leading to potential condensation.