Once the fire in flat 16 reached the exterior cladding, it spread with devastating speed. Within minutes, the building’s design, intended to contain a fire to a single flat, had catastrophically failed.
Vertical and Lateral Spread
From the fourth floor, the fire raced upwards and across the eastern face of the tower. Fire safety engineer Dr Barbara Lane, reporting to the Grenfell Public Inquiry, identified it spreading vertically up the tower columns and laterally along the cladding above and below the window lines and between the window panels.
01:26
Fire reaches the top floor (east side)
01:42
Fire spreads to the north face
01:52
Fire travels east towards the south
Less than 30 minutes after firefighters arrived, the blaze had reached the top of the 24-storey building.
Watch: The Fire Spreads
The “Stay Put” Policy
At 02:06, the London Fire Brigade declared a major incident. By then, around 40 fire engines were either on scene or en route.
Grenfell Tower operated a “stay put” fire policy: its design was supposed to contain any fire within a single flat long enough for crews to bring it under control. On the night, many residents were told by the emergency services to remain in their flats. As the fire raged out of control and thick, poisonous smoke filled the single narrow stairwell, many became trapped.
Dr Lane concluded that the stay put policy had “substantially failed” by 01:26, less than 30 minutes after the first firefighters arrived. Some residents who ignored the advice and left early made it down the stairs to safety.