Condensation Control

Condensation is by far the most common cause of dampness in buildings, probably accounting for the majority of damp problems reported. It affects both old and new buildings, but it appears to be a significant problem where the building has been modernised.Condensation is directly associated with mould growth. It is this that the occupier sees first, and it gives an indication of the potential scale of the problem. The mould is usually found on decorative surfaces, especially wallpapers, where it can cause severe and permanent spoiling. In many cases, the mould and its spores give rise to complaints about health, and cause the “musty” odour frequently associated with a damp house.The obvious places for condensation to occur are on cold walls, wiondows, and floors, but it can also occur in roof spaces and in sub-floor areas where there is a timber suspended floor; in the latter case, it can lead to dry rot or wet rot developing in floor timbers or joists.

The Cause

It is a fact that warm air can hold more water as vapour than cool air. Condensation is caused when moisture-laden air comes into contact with a cold surface – the air is cooled to the point where it can no longer hold its burden of water vapour. At this point, known as the “dewpoint,” water begins to drop out of the air, and is seen as condensation on surfaces. On impervious surfaces such as glass and gloss paint, beads or a film of water collect. On permeable surfaces such as wallpaper and porous plaster, the condensing water is absorbed into the material. Therefore, the problem is not always initially obvious.

Condensation is very much a seasonal problem, occurring during the colder months – October to April. During the summer, the problem is seen to go away.During the winter, ventilation of the house is usually low (due to windows and doors being closed, draught-proofing takes place). This allows build up of water vapour in the house, which, in some cases is sufficient to cause condensation. This condensation becomes apparent from the following symptoms:

• Water droplets form on cold, impervious surfaces such as glass and paint.
• Slightly damp wallpaper (often not noticed).
• Development of moulds, usually black mould.

In some cases, condensation may be long term, but intermittent, forming only at certain times of the day or night. In these cases, the only sign of condensation may be mould growth, as the moisture may have evaporated by the time moisture measurements are taken.One should also be aware that the problem can occur well away from the site of most water vapour production. E.g. water vapour produced in the kitchen may diffuse through the house into a cold bedroom where it will condense on cold walls.The control of condensation is based on two very simple primary measures, supported by a number of secondary measures.

If you think you have condensation issues call us now on 01656 746224 to book an appointment for one of our damp specialists to visit your premises to carry out tests using our condensation meter.