Cavity Wall Insulation Issues

Written by richard hoyt
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Since porous masonry eventually allows dampness to work its way indoors, the United Kingdom in the 19th century introduced wall cavities to block moisture. Wall cavities became widespread after the 1920s. To save energy, blowing insulation into wall cavities became widespread in the 1970s and was made compulsory in new buildings during the 1990s. The British government subsides cavity wall insulation on the grounds that it saves energy and reduces carbon dioxide emissions into the atmosphere; critics argue that there is one major problem: it allegedly causes damping or damp spots.

Old vs New Homes

Jeff Howell, a columnist for the "Sunday Telegraph," argues that damping is in fact a problem for houses that were built before the 1980s and subsequently had mineral or glass fibre blown into the wall cavities. He claims that samples of mineral or glass fibre insulation sent to him by readers held nearly 2 1/2 times their weight in water. He says the problem is worse in areas with rain that is driven by wind. Howell cites the Cavity Insulation Guarantee Association as saying these problems were due to construction faults in the building or condensation caused by lifestyle issues of the owners. Insulation blown into new homes have generally not had these problems.

Lifestyle Issues

Lifestyle issues cited by the Cavity Insulation Guarantee Association refer to people who allow the interior of their houses to go unheated. In most homes, the internal temperature is kept at 20 degrees C or 20 degrees C. At that temperature the relative humidity is usually between 50 to 60 per cent. This air will hit its dew point, when it changes to water, at 12.2 degrees C or 12 degrees C. When the temperature falls below this point, condensation will form on windows and other cold spots, usually a window. If installers of cavity wall insulation missed a spot, condensation will collect in that area.

Dampness Causes

Premier Heritage, surveyors of building preservation, says water can in fact soak cavity insulation because of loose joints and mortar, dirty wall ties, debris in the cavities and poor insulation techniques. However, Premiere Heritage argues that a majority of cavity wall insulated with blown insulation have not had problems.

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