Years after Grenfell Tower tragedy, buildings still wrapped in “solid gasoline”

At around 5.30 p.m. on February 22, a fire broke out on the 8th floor of a high-rise building in Valencia, Spain. These videos were taken over the next 45 minutes.

5:37 p.m.

In two hours, flames had engulfed the entire building, killing ten people.

Reuters consulted more than half a dozen experts who said the blaze was fuelled by the use of flammable materials in the high-rise’s cladding.

They said the fire showed that seven years after the deadly Grenfell Tower fire in London, which killed 72 people, its lessons had gone unlearned.

Two fire engineers told Reuters the main cause of the Valencia fire’s rapid spread was the flammable cladding made of aluminium and polyethylene, known as Aluminium Composite Material (ACM).

These panels serve as the exterior layer of some “ventilated facades,” a cladding system used on many new or renovated buildings. It is lightweight, energy-efficient and cost-effective.

The ACM panels mounted on a metal frame over insulation on the brick wall create an air cavity, which also contributed to the fire's spread.

What appears to be a solid metal panel is actually a sandwich of two thin aluminium sheets bonded to a layer of polyethylene — a petroleum derivative that is like “solid gasoline,” according to David Higuera, an industrial engineering technician.

Guillermo Rein, professor of fire science at Imperial College London, said that during a fire, the heat causes the thin aluminium foil to peel off: “exposing a building completely wrapped in extremely flammable fuel.”

Experts have identified ACM panels as the primary cause of the rapid spread of fire in Grenfell Tower and several other high-rise blazes. It still covers thousands of buildings worldwide.

El Campanar

Valencia, Spain

2024

Telecom Tower

Changsha, China

2022

Torre dei Moro

Milan, Italy

2021

Marina Diamond

Dubai, United Arab Emirates

2021

Grenfell Tower

London, United Kingdom

2017

Olympus Tower

Grozny, Russia

2013

Monte Carlo Casino

Las Vegas, United States

2008

Despite scores of deaths, building codes in many countries don’t require the removal of flammable polymers from cladding

The energy crisis of the 1970’s pushed architects to insulate buildings to reduce heating costs. Ventilated facades — a cladding system that creates an air gap for ventilation between a building’s exterior wall and a thin layer of rainproof cladding — became a popular option to improve energy efficiency.

But in the 1980s and 1990s, building codes in many countries didn’t consider the fire risk of cladding materials. Flammable polymers like polyethylene were available cheaply and were widely used in ACM panels.

These panels — which no longer meet fire safety standards in many countries, including Spain, France and Britain — remain on buildings.

A graphic showing a side view of a single ACM panel. The panel consists of three layers, a 3mm polyethylene core sandwiched between two 0.5mm sheets of aluminium.

A graphic showing a panel scaled to an average human. The ACM panels is 2 metres tall by 1 metre wide. ACM Panels are widely used to enhance the texture, colour and shape of the external facade.

In Spain, the first regulation that prohibited combustible cladding like polyethylene dates to 2006. The construction of the high-rise in Valencia started the year before.

Thousands of other buildings constructed in the decades before such regulations took effect remain cladded in ACM.

Using expert testimony and visual evidence, Reuters examined how cladding containing polyethylene can impair firefighters’ protocols for tackling fires in tall buildings and endanger residents.

Reuters consulted four experts in fire behaviour in high-rise buildings, as well as five firefighters, two engineers and two architects, and reviewed 8 reports where ACM panels were identified by investigators as the main cause of the rapid spread of the blaze.

A graphic showing the fire potential of ACM panels. Polyethylene is a petroleum derivative. When it burns, it releases the same heat energy as gasoline. One square metre panel of 3 mm thick polyethylene is equivalent to 3 liquid litres. The 6,000 m2 of polyethylene that wrapped the Valencia building are equivalent to covering it with the fire load of 18,000 litres of gasoline, the same as a standard tanker truck.

Note: Approximate values are given in megajoules per kilogram. The building surface area was calculated by industrial technical engineer David Higuera, who estimated the approximate surface area using the perimeter and height of each block.

Rein, the professor of fire science, said the polyethylene polymer used in the core of ACM presents an “unacceptable” risk in a fire and shouldn’t be used in building construction.

“It continues to burn even after the flame source is removed, generates toxic smoke and produces a large number of burning droplets,” he said.

At Reuters’ request, Rein’s department at Imperial College London conducted fire tests on an ACM panel with a polyethylene core without fire retardant.

The panel’s edge ignited within seconds of exposure to a flame.

Even after the flame is removed, the polyethylene layer fuels the spread of fire.

Polyethylene combustion produces large quantities of dark, highly toxic smoke — a leading cause of death in fires, according to two firefighters and two engineers who spoke to Reuters.

The polyethylene melts into fiery droplets, which can spread fire down a building’s facade.

ACM panels containing polyethylene are specifically banned today in at least seven countries — Britain, France, Germany, Spain, Portugal, Sweden and Finland — for buildings taller than 18 metres.

Except for Britain, which has been removing these panels since the 2017 Grenfell Tower tragedy, other European countries are not replacing flammable ACM panels, according to Frances Maria Peacock, a fire engineer who submitted to the Grenfell Tower Inquiry an analysis of the cladding design and fire spread behaviour.

During a fire, the aluminium plates split open and the melting polyethylene spreads the fire in the form of burning droplets and debris.

Videos of fires in Valencia, Grenfell and Torre dei Moro in Milan show hundreds of panels and melting polyethylene falling from the facade and burning on the ground.

“Nearly seven years have passed since Grenfell, and similar fires are still claiming lives,” Peacock said.

Grenfell Tower

Residential complex, Valencia

Grenfell Tower on fire. REUTERS

Fire in a two-building residential complex, Valencia. @algunchaval on X, posted on February 22, 2024

Peacock, in an investigation of the 2021 Torre dei Moro fire, found that melting material spread the fire to lower levels of the building and burning polyethylene released significant quantities of toxic smoke, particularly carbon monoxide. “It’s fortunate that the residents were able to evacuate the building before the interior was affected,” she said.

Fires fuelled by ACM polyethylene cladding pose significant challenges to high-rise firefighting strategies.

Firefighters often approach high-rise fires by instructing residents on floors above the fire to stay in their apartments and shelter in place rather than evacuate. Keeping residents in their homes protects them from exposure to toxic smoke that may fill exit routes like stairwells. Firefighters can then focus on isolating and extinguishing the fire on lower floors.

“If the building is well-constructed according to regulations, smoke shouldn’t enter the apartments,” said Antonio Novillo, a senior firefighter from Madrid and member of the Federation of European Fire Officers.

Each apartment in a residential building should be a fire-resistant compartment, providing occupants with at least 60 minutes of protection, Peacock said — long enough to isolate and contain a fire elsewhere in the building, ideally.

But because ACM polyethylene panels accelerate the spread of a fire along the exterior of buildings, fires can breach an apartment’s fire-safety perimeter from the outside, coming in through windows or balconies.

In this type of fire where the flames spread along the facade, “stay-put is no longer valid,” said Peacock.

The following animation shows how combustible cladding materials can disrupt firefighters' strategies.

Firefighters arrive and locate the origin of the fire. While evacuating residents from the lower floors, they instruct those on the upper floors to stay in their flats to avoid smoke inhalation.

In the worst-case scenario, fire and toxic smoke could spread through the stairs and common areas, preventing escape. Each flat should be a fire-resistant compartment, safe for at least an hour while firefighters work to suppress the fire.

The extremely flammable polyethylene in the panels quickly spreads the fire in all directions. The material melts into burning droplets that also propagate the fire downward. Residents and firefighters can become trapped between the smoke and the fire.

With fire spreading rapidly through flammable exterior cladding, firefighters can lose the ability to control or extinguish a multi-storey fire. The ‘stay put’ strategy can become a risk.

Óscar Romero, a resident of the Valencia building and a member of the association for property owners affected by the fire (Aproicam), told Reuters that a family of four - including a two-week-old baby girl - perished in their apartment after firefighters told them not to leave via the stairs.

Novillo, the firefighter from Madrid, said that during a crisis situation with a spreading fire, it can become increasingly difficult to communicate new orders to residents.

In the Valencia fire, Novillo said, “the momentum of the initial strategy, where some residents had already taken refuge in the bathroom, couldn’t be stopped, leading to the tragic loss of lives.”

The Valencia municipal fire department and Valencia’s provincial fire consortium did not respond to requests for comment. In a statement days after the fire, the provincial consortium expressed regret for the loss of life and said its team had adapted its strategy in real time, while applying safety protocols.

An investigation into the death of 72 people in the 2017 Grenfell Tower fire published two years after the tragedy underscored the urgent need to adapt fire strategies for high-rise buildings with flammable cladding. A final report is due this week.

According to the inquiry, a ‘stay-put’ strategy remained in effect for more than an hour, resulting in dozens of lost lives. The strategy effectively failed after just 12 minutes, when the fire spread to other flats. However, an evacuation order was only issued by the London Fire Brigade after 1 hour and 39 minutes, with 61 flats affected by the flames and 107 people still inside the building.

Only 36 of those who remained at that point made it out alive.

The following graphic illustrates the Grenfell fire’s spread along the facade and the number of residents remaining in the building before and after the ‘stay-put’ order was lifted.

A graphic timeline of the Grenfell Tower disaster. Initially, residents were told to “stay put.” Although the fire had spread to eight apartments within seven minutes, occupants not affected by fire or smoke were advised to remain in their apartments. There were 294 people inside the tower at about 1:14 a.m. The ‘stay put’ strategy began to fail when the fire spread to other flats through the external cladding. Twenty-two minutes later, 151 people were in the building. At this point the stairs were still free of smoke and tenable for escape. An hour and 37 minutes after the initial response, 137 residents were still inside. Only after 1 hour and 39 minutes, with 61 flats affected, were residents told to try to escape. From this point only 36 people were able to evacuate. 70 people died inside the building and 2 in hospital shortly thereafter.

Source: Grenfell inquiry

After Grenfell, Britain banned combustible materials on the external walls on all new buildings of any height. The Ministry of Housing, Communities and Local Government also initiated a program to remediate or replace unsafe cladding.

Last year, the British Government announced a £8.1 billion program to fix the most dangerous buildings where the original developer can’t be tracked down and made to remove or replace dangerous cladding.

Such replacement work is not being carried out in other European countries, where post-Grenfell restrictions on the use of polyethylene in facades apply to new buildings only, said Peacock, the fire engineer.

In Spain, where urban planning oversight and fire services are decentralized and managed by regional governments, after the tragedy of Valencia some architectural associations and municipal fire departments are conducting surveys in their regions to identify buildings with hazardous materials.

Novillo, the Madrid firefighter, said that only by knowing which buildings have these types of flammable facades can firefighters direct residents with a strategy “that prioritises evacuation over confinement.”

A graphic showing the progress of remediating buildings with fire safety issues due to external cladding in the UK. There are 4,630 residential buildings 11 metres and over with unsafe cladding, as at 31 July 2024. These include buildings with ACM panels and other external wall systems that require remediation or mitigation. Of these, 1,350 completed remediation; 949 had remediation underway; and 2,331 were yet to start unsafe cladding remediation.

Source: United Kingdom Department for Levelling Up, Housing & Communities.

In continental Europe, there are no national surveys of buildings with ACM polyethylene cladding. Some experts estimate there are thousands of such structures.

“Most countries don't want to ask how many buildings have it,” said Rein, “because if you start asking, you'll find a number you won't know what to do with.” Rein estimated that Spain has more buildings covered with ACM polyethylene cladding than Britain. “And if you have 5,000 buildings,” said Rein, “there could be a fire every year.”

Spanish building materials company Alucoil, which made the cladding for the building in Valencia, told Reuters it does not have a records of the buildings that use its panels because it sells to distributors rather than directly to property developers.

Alucoil also provided polyethylene ACM panels for Torre dei Moro in Milan, a tower destroyed by fire in 2021, and Torre Ambar in Madrid, which suffered a fire the same year that burned the top six floors.

Peacock said that the blazes in Valencia, Milan and Madrid all began as a localised fire inside an apartment, and within a few hours, the flames had spread widely due to the flammable cladding.

Alucoil stopped manufacturing polyethylene ACM panels in 2019, the same year that Spain's Technical Building Code prohibited their installation.

The company received a Technical Suitability Document (DIT) - a public certification that its product met the necessary technical and safety standards for building projects - in 2008 and again in 2015. Asked by Reuters about the use of combustible materials in its cladding in the past, Alucoil responded that “a material is not inherently good or bad, as its fire resistance depends on how it is applied.”

Enrique Salvador, vice president of the association of residents who lost their homes in Valencia, said that he had never thought about the risk of cladding until the fire struck in February.

“Now, I wouldn't move into a building with panels unless I have documentation confirming the safety of the facade materials,” he said.

Corrections

A previous version of this story incorrectly said the tower in Valencia had completed construction before the first regulation that prohibited combustible cladding went into effect in Spain in 2006. Construction had started the year before, but finished in 2008. Also, the first Grenfell Tower inquiry report published more than two years after the fire, not one.

Sources

Reuters consulted 8 fire reports on high-rise buildings, including Valencia, conducted by Frances Maria Peacock, a Chartered Architectural Technologist and a Fire Engineer. Grenfell Tower Inquiry. Spanish Professional Association of Fire Technicians, an organization that is part of the Federation of European Fire Officers. Antonio Roda Montes, technical architect, former chief of firefighters for the Ávila city council, and advisor to the Fundación Fuego. David Higuera, industrial engineering technician. Juan José Peralta, architect. Juan B. Echeverría-Trueba, architect and member of the Society of Fire Protection Engineers. Firefighter Óscar Prieto Merchán (Fire Officer with the Navarra Fire Service and Industrial Engineer). Spanish Building Code (2006, 2009 and 2019). Spanish Cadastre. Technical suitability document for Larson PE and FR panels conducted by the Eduardo Torroja Institute for Construction Sciences in 2008, 2015, and 2022. APROICAM (Association of Property Owners Affected by the Campanar Fire). Association and College of Industrial Engineers of Catalunya. Dr Laia Haurie (Universitat Politècnica de Catalunya).

Videos

The first three videos, which showcase the development of the fire in Valencia's building, were recorded by Carlos Estella. The fire test videos on an ACM panel with polyethylene core were recorded by Dr. Carlos Walker-Ravena and Professor Guillermo Rein, from the Department of Mechanical Engineering of Imperial College London. The panel used in the test has similar, if not identical, characteristics to those present in Valencia, Torre dei Moro and Grenfell Tower.

Images

El Campanar (REUTERS/Eva Manez); Torre dei Moro (Vigili del Fuoco/Handout); China Telecom Tower (Wikimedia Commons); Marina Diamond building (Google Street View); Grenfell Tower (REUTERS/Toby Melville); Olympus Tower (REUTERS/Yelena Fitkulina); Monte Carlo (REUTERS/Las Vegas Sun/Steve Marcus).

Edited by

Daniel Flynn and Jon McClure