LONDON — Some of the 72 people who died in the Grenfell Tower fire in 2017 would have survived if firefighters and emergency operators had not told them to stay in their apartments, according to a government report to be released on Wednesday.
The 1,000-page report, which comes more than two years after the deadliest fire in recent British history, is harshly critical of the London Fire Brigade, calling it dangerously unprepared for such a tragedy, according to multiple British news organizations that gained access to the conclusions before their release.
The fire on June 14, 2017, began on the fourth floor of the 24-story building and spread rapidly upward because of flammable exterior cladding and insulation that had been added to the building the year before.
Those outer layers would not have been allowed on a high-rise in many countries, including the United States, because of the fire danger they posed.
The report is to be released to the public on Wednesday. The work of an official inquiry led by Martin Moore-Bick, a former appellate court judge, it does not go in depth into the tower’s renovation and the materials used in it.
The next phase of the investigation is expected to do so, but firefighters and survivors of the blaze have criticized the investigation for not tackling those questions first. They contend that the unacceptable level of danger built into the tower outweighed any mistakes made on the night of the fire.
In recordings made that night, firefighters arriving at the scene expressed horror at how fast the flames were spreading, and bewilderment at how it was possible.
Matt Wrack, the chief of Britain’s main firefighters’ union, said in a Twitter post on Tuesday that “firefighters did not put flammable cladding on Grenfell Tower,” but risked their lives in it. He accused the government of doing “nothing substantive” since then.
Britain had lax construction standards compared with many other countries — a decision approved by successive governments to let builders save money. Tests conducted to determine whether materials met fire safety rules were also lax, allowing products that had undergone limited testing in laboratories — but then failed under real-world conditions.
In 2005, Britain stopped requiring certifications from government inspectors that a building complied with fire codes, allowing builders and owners to police themselves.
Mr. Moore-Bick found that the fire brigade had no evacuation plan for Grenfell, that it had failed to instruct firefighters on the risk created by the cladding and insulation, and that it was too slow to deploy crews with breathing apparatus. There were not enough emergency operators to handle all the calls they received.
But the report found that the biggest failing once the inferno began was that for nearly two hours, residents were instructed to stay in their apartments with their doors closed. The first emergency call went out at 12:54 a.m., and it was not until 2:47 a.m. that the decision was made to evacuate.
“That decision could and should have been made between 01:30 and 01:50 and would be likely to have resulted in fewer fatalities,” the report states, according to the BBC.
The report was shown in advance to relatives of the dead and people who escaped the fire, but they declined to comment on Tuesday, because they had agreed not to discuss it until its official release.
The tower, built in 1974 in the North Kensington neighborhood, lacked fire alarms, sprinklers or fire escapes, and had just one internal staircase. Residents had complained for years that it was unsafe.
The advice to shelter in place is common in buildings with inner and outer walls made of concrete, which is expected to slow the spread of fire within the structure.
But at Grenfell the fire spread from the outside in, leaping up the sides of the building on the cladding and into apartments through the windows.
The fire brigade has acknowledged some of the mistakes made that night. Andrew Dismore, the chairman of the fire and emergency planning committee of the London Assembly, the elected panel that oversees city governance, has said that “significant progress is being made with new training, equipment and policies.”
After the Grenfell tragedy, hundreds of high-rise buildings around Britain — apartment blocks that are home to thousands of people, college dormitories and hospitals — were found to have similar cladding and insulation.
The government said it would all be removed and replaced, but more than two years later, many people are still living in buildings sheathed in the same kind of flammable material.
Other buildings are clad in nothing more than bare concrete, because their dangerous exteriors were removed, but owners, residents and government officials continue to fight over who will pay to replace it.