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Thursday, July 7, 2022

Grenfell Tower: Finally, the worst type of cladding to be banned, five years later

Five years after the Grenfell Tower fire on June 14, 2017, killed 72 people, the UK government announced plans to ban the type of cladding used to cover the exterior walls of the North Kensington high-rise is of. These revised building rules are to be implemented in December 2022.

The disaster investigation concluded in its first report in 2019 that this cladding – aluminum composite panels filled with polyethylene, to be specific – was responsible for the fire spreading so quickly.

Polyethylene-filled aluminum composite panels are lightweight, tough and inexpensive. They are coated with durable paint and can be easily formed into architecturally interesting shapes.

Of all the common plastics, polyethylene ignites the most easily and gives off the most heat when burned. Because its chemical composition is similar to that of petrol, when it is melted, it burns violently with high heat release.

The central component of the cladding panels – polyethylene – is highly combustible.
John Gomez | Shutterstock

a multistage fire hazard

Polyethylene filled aluminum composite panels are typically a 4 mm thick composite of two sheets of 0.5 mm aluminum sheet sandwiching a 3 mm layer of polyethylene. If heated by fire, polyethylene melts and precipitates out, where it can easily burn, causing the flames to spread downward through the flames, droplets of molten.

However, the panels aren’t the only problem. “Rainscreen” cladding systems, which are attached to the exterior walls of large modern buildings to improve appearance and thermal insulation, These exterior cladding panels consist of an internal ventilation cavity (50 mm wide) and a layer of insulation (100 mm by 200 mm). ) are combined with. thick).

This means that going outside, after the cladding panels, has a ventilated cavity and insulation, which is often combustible (usually phenolic foam or polyisocyanurate foam in the UK). This provides additional fuel to the fire, which burns more slowly. As a result, the contents of individual flats can catch fire. There could be catastrophic loss of life, as in the Grenfell Tower fire.

Crucially, the air-gap, which is used to prevent moisture build-up, acts as a chimney. This allows the flames to rise upwards inside itself, which is inaccessible to the hoses of firefighters.

Conversely, in incidents where polyethylene-filled aluminum panels have ignited on buildings without insulation, such as the 2016 fire at the Address Downtown Hotel in Dubai, or the 2014 fire at the Lacrosse Building in Melbourne, flames spread to the outside of the building. have spread. Within minutes, but the life is not lost.

Fire Hose Rolled Over A Fire Truck
These cladding systems make it difficult for firefighters to access internal air gaps.
Azmi Adiputra | shutterstock

inadequate regulation

Other cladding panel types include high-pressure laminates (similar to the material used to make kitchen worktops), which also burn with disastrous results. This is what happened in the 2009 fire at Lucknall House in London and the 2019 fire at The Cube in Bolton.

It is estimated that three times more buildings are wrapped with this laminate. The combination of both types of cladding panels (polyethylene-filled aluminum composite and high-pressure laminate) has left thousands unable to sell their homes.

Since the Great Fire of London in 1666, the use of combustible walls and roofs has been banned in England. The 2010 building regulations state that “the exterior walls of the building shall adequately resist the spread of fire on the walls and from one building to another, taking into account the height, use and position of the building”.

But guidance on how this regulation could be met was given in the 2006 edition of the UK government’s 180-page Fire Safety: Approved Document B. It states that this can be achieved by using non-combustible products on exterior walls. building, but it also allowed the use of combustible products, provided they were exposed to fire in a large scale test (following the BS 8414 test standard) under certain criteria (separately in the document known as BR135). published).

Our research has shown the inadequacy of this approach, as the ideal test environment differs greatly from the actual building. This guidance essentially made possible the use of flammable products on the exterior walls of tall buildings. It is required that these products either meet BR135 criteria, or, in the absence of test results, a fire consultant performs what is known as a “desktop study” to determine whether they are likely to meet the criteria. have chances.

Climate change was used by the insulation industry to persuade regulators to increase the insulation requirements of modern buildings to conserve heat. This was done without considering the fire safety consequences.

The climate emergency is undoubtedly the greatest threat to humans and our planet. Household space and water heating account for about 20% of carbon emissions, and insulation reduces those emissions. But there are many ways to reduce carbon emissions, starting with leaving fossil fuels in the ground.

Some insulation products, such as glass wool and stone wool, are non-combustible, and can be safely placed on the exterior face of a building. Other insulation products (such as those phenolic or PIR foams, which are themselves derived from fossil fuels) have been shown to be fire safe only when enclosed in concrete masonry. However this is more expensive, and may not be possible when renovating an existing building.

The Grenfell investigation has revealed gaps in procedures for ensuring fire safety from product manufacturers, testing laboratories, third-party certification, builders, architects and even regulators.

From a regulatory standpoint, allowing combustible products to be used on exterior walls in the first place has proved counterproductive. In many cases, they have actually been removed but not replaced. This has improved fire safety, but the occupants of the insulation benefited from this before.

In addition, the carbon emissions associated with the treatment of buildings after the Grenfell Tower fire to ensure fire safety are likely to outweigh the potential savings from improved insulation. As a result, if non-combustible insulation and non-combustible cladding panels were specified by building regulations, not only could the Grenfell tragedy be avoided, but the adverse climate impacts of all other unsafely clad buildings could ultimately be reduced. could.

World Nation News Desk
World Nation News Deskhttps://worldnationnews.com/
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