Grenfell: refurb created “catastrophic fire routes”

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The refurbishment of the Grenfell Tower created "catastrophic fire-spread routes" that led to the death of 72 people in a blaze at the building in June last year.

That’s according to Arup fire safety expert, professor Barbara Lane, whose report into the disaster was one of a number to be published yesterday as part of the Grenfell Tower Inquiry.

Lane issued a damning verdict on the rainscreen cladding system that had been added to the building as part of its refurbishment between 2012 and 2016, determining that it was "non-compliant with the functional requirement of the Building Regulations".

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She also found that all of the fire doors between the fourth and 24th floors were “not compliant with fire test evidence relied upon at the time of installation”.

Many of the doors failed in 20 minutes instead of the 60 minutes required by regulations.

In the conclusions of her report she said: "Based on the relevant test evidence submitted to the public inquiry, the construction materials forming the rainscreen cladding system, either individually or when assessed as an assembly, did not comply with the recommended fire performance set out in the statutory guidance of Approved Document B (ADB) 2013 for a building of that height."

She added: "I conclude the entire system could not adequately resist the spread of fire over the walls having regard to height, use and position of the building. Specifically, the assembly failed adequately to resist the spread of fire to an extent that supported the required Stay Put strategy for this high-rise building."

The primary cause of the early stages of the fire spread was the interface between the kitchen window in flat 16, where a kitchen fire broke out, and the horizontal rainscreen cladding system above the window, she found.

Lane said the detailing around old and new windows in the building, which also hadn’t been provided with fire resisting cavity barriers, meant that the materials and the way in which they were arranged increased the likelihood of fire breaking out and spreading into the large cavities contained within the cladding system, which contained combustible materials.

While attempts had been made to subdivide the column cavities to provide horizontal and vertical fire stopping at key compartment lines, she found that the fire stopping was installed incorrectly and that no evidence had been provided that they were ever tested for performance in an ACP-based rainscreen cladding system of the type installed at Grenfell Tower.

Lane added: "Once the fire entered the rainscreen cladding system outside flat 16 on the east elevation, the Reynobond 55PE rainscreen cladding later coupled with the ventilation cavity backed by the Celotex insulation or Kingspan K15 insulation, incorporating defective vertical and horizontal cavity barriers, failed to control the spread of fire and smoke.

"The Reynobond 55PE contributed to the most rapid of the observed external fire spread."

Meanwhile she issued a damning verdict on the design and construction team involved in the refurbishment. She said: "I have found no evidence yet that any member of the design team or the construction ascertained the fire performance of the rainscreen cladding system materials, nor understood how the assembly performed in fire. I have found no evidence that building control were either informed or understood how the assembly would perform in a fire.

"Further, I have found no evidence that the [tenant management organisation] risk assessment recorded the fire performance of the rainscreen cladding system, nor have I found evidence that the LFB risk assessment recorded the fire performance of the rainscreen cladding."

And another expert fire engineer, Colin Todd, said that it appeared the aluminium composite cladding material (ACM) used on Grenfell had never been subject to a full scale British Standard fire test.