Building safetyFact Check: is the type of cladding used on Grenfell Tower actually banned in Britain?
Cladding was added on tower blocks built in the 1960s and 1970s such as Grenfell Tower to improve the thermal performance of the flats and in some cases prevent material deteriorating and falling from the existing facades. These flats are often homes to some of the poorest in society and improving the facades may cut their energy bills to less than a half. This also means that they can adequately heat their homes to avoid condensation and mold growth inside. After the devastating fire at Grenfell Tower, the Metropolitan Police is considering whether to bring manslaughter (or other) charges relating to the tower block’s insulation, which it says failed safety tests.
“My understanding is that the cladding in question, this flammable cladding which is banned in Europe and the US, is also banned here.”
Philip Hammond, the U.K. chancellor of the exchequer, speaking about the Grenfell Tower fire on the BBC’s Andrew Marr show
on 18 June.
After the devastating fire at Grenfell Tower, the Metropolitan Police is considering whether to bring manslaughter (or other) charges relating to the tower block’s insulation, which it says failed safety tests. The cladding on another eleven high-rise buildings has also failed fire safety tests, according to the communities secretary, Sajid Javid.
Cladding is being added on tower blocks built in the 1960s and 1970s such as Grenfell Tower to improve the thermal performance of the flats and in some cases prevent material deteriorating and falling from the existing facades. These flats are often homes to some of the poorest in society and improving the facades may cut their energy bills to less than a half. This also means that they can adequately heat their homes to avoid condensation and mold growth inside.
The existing buildings have concrete or blockwork walls with a thin layer of insulation on the inner surface. The thermal improvement is achieved with a layer of insulation placed on the outer surface of the existing external wall where it is not impaired by condensation. Because of this, it is necessary to shelter the insulation from the weather. This is done with an outer layer of panels, called the rainscreen. A cavity is left between the insulation and the rainscreen to drain any water that passes joints in the rainscreen.
Fire may spread extensively up the wall if the insulation is combustible, if smoke and flame can travel up the cavity or if the rainscreen is combustible. In practice, fire barriers are placed in the cavity at each storey to prevent the movement of smoke and flame and separate the insulation into story-height portions. This limits any spread of fire through the insulation which should be of limited combustibility in high rise buildings.
Many materials have been used for rainscreens in the United Kingdom, ranging from lightweight metal panels, through composite boards and terracotta to natural stone on upmarket city offices. Aluminum composite materials (ACM) are used as a lightweight economical solution that can be readily formed into different shapes with different surface finishes.
