How they built Grenfell Away from the media spotlight, the Grenfell Tower inquiry is quietly disentangling a web of corporate spin and scandal. In December 2007, an Irish building materials company called Kingspan tested the fire safety of one of its insulation materials, Kooltherm K15. It was tested on a rig mocked up like a building, to mimic how the product might be used in real life, with aluminium cladding panels on a steel frame six metres tall. It created a “raging inferno”, according to one of the test’s observers from Kingspan. The Building Research Establishment (BRE), the certification body that carried out the test, had to stop it early because it risked setting fire to the laboratory. Even after the heat source was extinguished, the product continued to burn on its own.