Moisture levels in your home can come from a lot of different factors, such as:

- Cooking without an extract fan

- Baths & Showers in a badly ventilated bathroom

- Drying your washing on your radiators or similar

- Unvented tumble dryers

- Boiling a kettle

- Climate factors outside of the house

- Leaking or blocked guttering or pipes

- Damp walls or unsealed windows

- Breathing (!)