Ensure that tumble dryers have adequate ventilation, and leave a gap between your furniture and walls.

Warm moist air from inside the house rises up and condenses on the cold surfaces inside the chimney; without adequate ventilation, this will lead to damp.

If you have a persistent problem, check you have adequate ventilation, such as a functioning fan and window trickle vents, and that air bricks are not blocked.

It also helps if plants are planted in well-drained soils, at intervals appropriate for adequate ventilation between plants.

This was installed to provide adequate ventilation in a mine.