Grenfell Tower was part of the Lancaster West Estate, a council housing complex in North Kensington. The 24-storey tower block was designed in 1967 in the Brutalist style of the era by Clifford Wearden and Associates, and the Kensington and Chelsea London Borough Council approved its construction in 1970. The building was constructed by contractors A E Symes of Leyton from 1972–74.

Like many other tower blocks in the UK, Grenfell Tower was designed to be operated under a “stay put policy” in the event of fire. The idea was that if a fire broke out in one flat, thick walls and fire doors would contain the fire long enough for the fire service to bring it under control. Only those in the affected dwelling would be expected to evacuate. The building was designed under the assumption that a full evacuation would never be necessary. There was no centrally activated fire alarm and only a single central staircase. Unlike in many other countries, UK regulations do not require a second. In 2010, a fire broke out in a lobby and was quickly extinguished.

On 14 June 2017, a fire broke out in the 24-storey Grenfell Tower block of flats in North Kensington, West London, at 00:54 BST; it caused 72 deaths, including those of two victims who later died in hospital. More than 70 others were injured and 223 people escaped. It was the deadliest structural fire in the United Kingdom since the 1988 Piper Alpha disaster and the worst UK residential fire since the Second World War.

How the fire started?

The fire began “in or around” a Hotpoint fridge-freezer in flat 16 on the fourth floor, according to a provisional report by Dr Niamh Nic Daéid, director of the Leverhulme Research Centre for Forensic Science at Dundee University.

Her report contains extracts from a witness statement by flat occupant Behailu Kebede, who described being woken by the sound of a smoke alarm.

He went into the kitchen and saw smoke in the area of the fridge-freezer and near the kitchen window.

Mr Kebede immediately called the fire brigade, which logged the call at 00:54. Four fire engines were sent to the scene, the first arriving at 00:59.

The first fire crew entered the flat at 01:07 – an approximate timing taken from a thermal imaging camera. They initially searched the bedrooms and did not enter the kitchen until 01:14.

In the kitchen, firefighter Daniel Brown described seeing an “isolated curtain of flame from about 2-3 feet in the air to the ceiling”.

Thermal images captured by the fire crew appear to show that “hot fire gases and flames had spread across the window space”.

As the fire crew dealt with the fire in the fridge-freezer, their thermal images also appear to show falling embers outside the kitchen window.

 

Mobile phone images taken by Mr Kebede from outside Grenfell Tower approximately 11 minutes after his first 999 call show an orange glow of flames around the kitchen window, and later a fire burning more intensely in the area of the window filler panel and extractor fan.

Subsequent photos by Mr Kebede suggest that the “fire was continuing to develop and grow”, Dr Nic Daéid reports, by 01:09 becoming “external to the building”.

Although the timings provided are approximate, it appears that the fire had spread to the cladding before the firefighters had entered the kitchen.

Dr Nic Daéid’s provisional report also identifies “unknown materials” stored between the freezer and wall which “may have become involved in the fire in the early stages of its development”.

Among these materials was an item described as an “electric cooking device” or “large hot plate”.

In another report, fire expert Professor Luke Bisby expressed his view that the likely reason for the fire spreading beyond the kitchen was that flame and hot gases penetrated the internal window frame.

How the fire spread?

From the fourth floor, the fire spread rapidly upwards and across the eastern side of the building. From there, it spread across the north face of the tower.

Mobile phone videos show the blaze reaching the top floor on the east side of Grenfell Tower by about 01:26, less than 30 minutes after firefighters had arrived.

In a report to the Grenfell Public Inquiry, fire safety engineer Dr Barbara Lane identified the fire spreading vertically up the tower columns, and “laterally along the cladding above and below the window lines (and) the panels between windows.”

The fire had spread to the north side of the tower by 01:42, Dr Lane recorded.

At 01:52, the fire also began travelling across the eastern side towards the south in the other direction.

At 02:06, London Fire Brigade declared the fire a “major incident”. At this point, some 40 fire engines were either at or en route to the scene.

Grenfell Tower had a ‘stay put’ fire policy – essentially, the building design would contain a fire in a single flat for as long as it took fire crews to bring it under control.

So on the night, many residents were told to remain in their flats by the emergency services, only to become trapped as the fire blazed out of control and thick poisonous smoke spread up the single narrow stairwell.

Dr Lane said that the stay put policy had “substantially failed” by 01:26 – less than 30 minutes after the first firefighters were at the scene.

Some people ignored the stay put advice and made it down the stairs to safety.

A total of 65 people were rescued from the building by firefighters.

 

But in desperation, other residents went upwards and sought refuge in flats of friends and neighbours on the upper floors. Twenty-four people died on the top floor of the tower block.

By 02:10, multiple internal fires could be seen burning inside the building.

At 02:22 fire had spread to the south side of the tower and by 02:30 it was reported that the eastern side of the building was “fully involved in fire”.

The stay put advice was finally abandoned at 02:47, when the incident commander gave the order to “advise people to make efforts to leave the building.”

Counsel to the Grenfell inquiry Richard Millet QC told the 4 June 2018 hearing that 144 people managed to evacuate before 01:38, but only 36 after the stay put guidance was abandoned.

By 02:51, the fire had reached the western side. At this point, some 63 flats were on fire and more than 100 people remained in the building.

At 04:30 the whole building was engulfed, with more than 100 flats on fire.

The blaze did not burn itself out until 01:14 BST on Thursday – 24 hours later.

What caused the fire to spread so quickly?

The most significant part of the renovation of Grenfell Tower was the addition of external cladding. This consisted of aluminium sheets bonded to a central plastic (polyethylene) core.

In his report to the public inquiry, Professor Luke Bisby said evidence “strongly supports” the theory that the polyethylene material in the cladding was the primary cause of the fire’s spread.

“The ACM (aluminium composite material) product on Grenfell Tower incorporates a highly combustible polyethylene polymer filler which melts, drips, and flows at elevated temperature. The polyethylene filler material is expected to release large amounts of energy during combustion”.

His report also suggests that vertical cavities within the cladding structure played a role in the spread of the fire, as did the insulation, although evidence was inconclusive.

A number of other flammable materials, including a polyurethane polymer foam insulation board which pre-dated the refurbishment were also present and may have contributed, Prof. Bisby found.

In her report, fire expert Dr Barbara Lane identifies combustible materials used in the refurbishment of the tower’s windows as another factor in allowing the fire to spread.

The Grenfell Inquiry has also heard that the building’s smoke extraction system was not working, and that firefighters experienced problems with the water supply because there was no ‘wet riser’ – a water-filled pipe running up the building to be used in the event of fire.

Giving evidence to the inquiry, Dr Lane said exposed gas pipes installed in 2016 were another contributory factor, while none of the flat doors met current fire resistance standards.

Work done on the lifts in 2005 and 2012-16 left them unfit for evacuating vulnerable residents and aiding the emergency response, Dr Lane said.