As Energy Conservation is required more these days and all the natural ventilation has been greatly reduced. With the introduction of double glazing, central heating and more efficient draught proofing houses have become effectively sealed boxes, keeping in any moisture produced within the house and providing ideal conditions for condensation to occur. Ventilation is only effective if it is throughout the whole of the property.
Condensation is assisted by poor air circulation, places where air movement behind furniture and in cupboards is restricted this allows moist air to gather. The first evidence of this is often the appearance of mould and sometimes with a musty smell on clothes in wardrobes. The warm, moist air rises from kitchens to the bedrooms, wardrobes and upstairs bathrooms and toilets. In bathrooms and kitchens the air contains a lot of moisture; if that air then spreads to cooler parts of the house it condenses on any colder surface.
Tumble dryers are a major source of moisture within a property unless they are vented externally or a condensating type of Dryer which collects the water and has to be emptied away.