The cladding system on the outside of London's Grenfell Tower was so conducive to the spread of fire it did not support the "stay put" policy normally in place for a building of its type, a report has found.
The "stay put" strategy pursued by the fire service on June 14 last year had "effectively failed" barely half an hour after the fire started at 1.26am, Dr Barbara Lane wrote.
She also claimed that the key players involved in the 2016 refurbishment had not ascertained how the new cladding system would behave in a fire.
Fire safety engineer Dr Lane made the remarks in an expert report commissioned by the Grenfell Tower inquiry on the fire protection measures within the 25-storey building where 71 people died.
Tests showed the materials forming the cladding system, individually and together, did not comply "with the recommended fire performance" set out in guidance for a building of that height, the report said.
"Additionally, I conclude that 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 residential building," Dr Lane wrote.
"There were multiple catastrophic fire-spread routes created by the construction form and construction detailing."
The windows lacked fire resisting cavity barriers and were surrounded by combustible material, meaning there was a "disproportionately high probability" of fire spreading to the cladding, she added.
Dr Lane wrote: "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."
Neither the Tenant Management Organisation nor London Fire Brigade recorded how the cladding would respond to a fire in their risk assessments, she said.
Seventy-one people were killed during the tragedy in Kensington, west London, on June 14 last year.
Another died in January after a long battle with a pre-existing condition, having never left hospital since the fire.
Four further expert reports have been released as the first day of evidence gets under way before Sir Martin Moore-Bick in central London.
Australian Associated Press
