What Causes Condensation?

Condensation forms when moisture in indoor air reaches a surface cold enough for water vapour to become liquid. It may occur alongside leaks, insulation defects or other moisture sources, so recurring mould should not be diagnosed from appearance alone.

Relative Humidity and Dew Points

Cooking, bathing, drying clothes and breathing add moisture to indoor air. When that air meets colder glazing, external corners, lintels or poorly insulated surfaces, the local temperature can fall below the dew point and condensation forms. Furniture placed tightly against cold walls can reduce airflow and make local conditions worse.

How can condensation risk be reduced?

Useful measures can include using suitable kitchen and bathroom extraction, keeping intended background vents clear, reducing avoidable moisture and heating consistently where practical. The right approach depends on the building, occupancy and whether cold bridges, leaks or defective fans also need attention.