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Cavity barriers play critical role in restricting fires

Correctly-installed cavity barriers play a critical role in restricting the spread of fire in timber-framed buildings, new research from the NHBC Foundation has found.

The unseen spread of fire within cavity walls creates serious threats to life and property and there is a growing body of anecdotal evidence that suggests methods used for protecting cavities are not performing properly.

The NHBC Foundation and BRE Trust commissioned research into fire spread within external walls where the cavity between the external façade and the structural frame is incorporated either as a lining material or as a form of insulation combustible material (or both). As part of the project, 21 fire experiments were carried out with the support of organisations including the London Fire Brigade, the Department of Communities and Local Government and the UK Timber Frame Association.

The NHBC Foundation report Fires in Cavities in residential buildings concludes that all generic forms of cavity barrier are capable of inhibiting the spread of fire when installed strictly in accordance with manufacturers recommendations.

The report contains clear guidance for the installation and inspection of cavity barriers for builders, designers, building control authorities and other building professionals.

Statistics from the London Fire Brigade found that of out of a total of 30,086 building fires attended in London between 2009 and 2011, 92 cases were identified where the fire had spread through gaps or voids in the construction resulting in fire spread beyond the floor of origin to other floors or the whole building.

Graham Perrior, Head of Standards and Technical, NHBC, said: “Cavity fires in timber-frame buildings are a relatively rare event. However, there are concerns about the unseen spread of fire within wall cavities and roof voids in timber-frame buildings. Such fire spread creates serious threats including potential life safety issues and extensive property damage.

“It is clear that correctly-installed cavity barriers play a critical role in restricting the spread of fire in timber-framed buildings. Everyone involved in the building and site supervision process needs to be aware of these important findings, which could save lives.”

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