Experts uncover reasons for spread of fire in roof voids
Four potential key reasons for the spread of fire in roofing voids were identified in a new major study by fire safety experts commissioned by the Government. The study, commissioned by the Department for Communities and Local Government, investigated a number of specific issues relating to fire compartmentation in roof voids, carried out by a team of experts from Exova Warringtonfire and Butler and Young Ltd.
The key reasons identified for the spread of fire in the study were: combustible materials spanning beneath the non-combustible roof covering;lack of or poor installation of cavity barriers along the soffit and heat transfer through penetrations. At the same time, the difficulty facing fire crews gaining access to the cavities and voids of timber framed buildings was highlighted.
The safety experts carried out the study following a number of fires in relatively modern apartment buildings which resulted in fires in roof voids which spread quickly throughout the roof affecting all the top floor flats. The purpose of the investigation was two-fold, to determine if recent, and current building practice follows the guidance in the recognised building control regulation Approved Document B and if not why not. The other reason was to conduct research into fires within roof voids.
There was a variation of the amount of detailed information provided in the submissions with a large proportion containing insufficient design detail of roof void compartmentation to allow the inspector to confirm compliance at the plan checking stage.
It was also noted that a number of submissions were considered as good practice as they were clear and concise and were supplemented by three dimensional drawings of the wall and roof interface showing the multiple interface layers.
For each fire that was investigated, the evidence showed that where the compartmentation was designed and installed in line with the recommendations of Approved Document B, it succeeded in preventing fire spread. Construction details shown in Building Regulations applications for approximately 750 residential buildings were reviewed.
Exova Warringtonfire is a recognised specialist in all aspects of fire safety including testing, certification, consulting and risk assessment, while Butler and Young provide a comprehensive service of building control advice throughout the process. Exova Warringtonfire and BYL Ltd expressed their appreciation for the help they received from all of those who contributed to the exercise including 12 fire and rescue authorities.
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