The Government has undertaken a consultation on proposals to lower the threshold on the ban on using combustible construction materials from buildings of 18m to 11m. This would reduce the maximum height of timber-framed buildings from six storeys to four.
However, the recent spate of timber-framed fires means that even that reduced height may be questionable. The consultation findings are due to be reported later this year.
The ‘Building a Safer Future’ consultation proposed reforms to England’s current building safety regulations following the Grenfell Tower tragedy. Initially, it was to examine the prohibition of using combustible cladding systems. However, a series of timber building fires has resulted in calls to ban the use of combustible materials for muti-storey building structures.
These fires include low-rise multi-storey buildings. Last September, a major fire reduced a four-storey timber-framed block of flats at Worcester Park in South-West London to ashes. In August, a three-storey timber-framed retirement development collapsed after a devastating fire. Meanwhile last November following a fire at a student accommodation block in Bolton, the Fire Protection Association called for a complete ban of the use combustible materials for all buildings regardless of their height.
“Timber is not a suitable construction material for either high-rise or low-rise multi-storey buildings. Unlike reinforced concrete which provides up to 6 hours of inherent fire resistance and structural integrity, timber frame offers just 30 minutes,” said Steve Elliott, Chairman of the British Association of Reinforcement.
Elliott also questioned the use of cross laminated timber which is being forwarded as a structural frame option because it chars rather burns and has higher strength than timber frame. He said: “Cross laminated timber is being touted as a structural option for multi-storey construction as a layer of charring is thought to prevent the structural component from burning. However, charring is burning and will have a significant impact on structural integrity. To say that charring is not burning is being disingenuous.”
He concluded: “There is too much real-time evidence of the unsuitability of timber for multi-storey construction. Building for a safer future must recognise the simple fact: timber burns.”