Why the Fire Spread So Quickly: The Cladding
The fire in flat 16 should have remained a contained kitchen fire. Instead, it engulfed a 24-storey building. The primary reason was the material wrapped around the outside of the tower.
The most significant element of Grenfell’s 2012–16 refurbishment was the addition of external cladding: aluminium sheets bonded to a central polyethylene (plastic) core. In his report to the Public Inquiry, Professor Luke Bisby concluded that this material was the primary cause of the fire’s rapid spread.
The polyethylene filler is highly combustible: it melts, drips and flows at elevated temperatures, releasing large amounts of energy during combustion.
Adapted from Prof. Luke Bisby’s report to the Grenfell Tower Inquiry
Bisby also found that vertical cavities within the cladding structure acted as chimneys, accelerating the upward spread. Insulation behind the panels and a pre-existing polyurethane foam board may also have contributed.
The cladding was not the only problem. Fire expert Dr Barbara Lane identified a series of additional failures that compounded the disaster:
Window materials
Combustible materials used in the refurbished windows allowed fire to enter flats from outside.
Smoke extraction
The building’s smoke ventilation system was not working on the night of the fire.
No wet riser
There was no water-filled pipe running up the building, forcing firefighters to work with inadequate supply.
Exposed gas pipes
Gas pipes installed in 2016 were left exposed, adding further risk as the fire took hold.
Fire doors
None of the flat doors met current fire resistance standards.
Lifts
Work carried out in 2005 and 2012–16 left the lifts unfit for evacuating vulnerable residents or aiding the emergency response.