Hidden condensation perils

Thinkstock48754714-roof-condensationMany of us recognise that water trickling down windows and mould patches in corners or bay windows are signs of condensation. However, under certain circumstances hidden condensation can cause some surprising and damaging problems.

Sometimes efforts to keep our properties warm can lead to unexpected condensation issues, especially if ventilation is reduced. If a property is fully insulated and the windows are double glazed, the original draughts that once removed the excess moisture we produce during our everyday lives are reduced. This can lead to condensation occurring in hidden or infrequently visited areas, which may go unnoticed.

Above – Lofts and attics

Warm air full of water vapour will build up in a property and can pass up through the ceiling into the loft space, where it mixes with colder air and if it cannot escape will condense. Sometimes when double layers of insulation have been fitted in a loft the natural eaves ventilation becomes blocked. This may allow the loft to become damp and homeowners can discover the timbers in their loft become mouldy. If one slope of the roof is in the shade and the other sunny, mould may only form on the colder side in the shade. The loft space can even become damp to the point where it may ‘rain’ inside! If water tanks are left uncovered and water evaporates, a similar effect may be seen.


Below – under floors

Good under floor ventilation is vital in protecting a properties flooring. Air bricks perform an important task, keeping under floor areas and timbers dry. If the soil below the floor is excessively wet and ventilation is poor, it’s possible that condensation could form on the underside of the floor. This could allow wood rotting fungi to start decaying the timbers. The situation can often be improved by  installing extra air bricks to improve ventilation. There are times when the soil is so wet, it requires a plastic membrane covering to reduce evaporation.

Interstitial condensation

This is a form of structural damp that occurs when warm, moist air inside a wall, roof or floor structure cools and reaches the dew point, condensing into water within the building material. Interstitial condensation can occur within masonry and insulated cavity walls, but it is difficult to detect until significant damage has occurred.

It is always important to seek the advice of property care specialists when evaluating the causes of your specific condensation issues as every situation is different.

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