Britain’s investigation into the 2017 Grenfell Towers fire that killed 72 people has reached its initial conclusions covering how the fire
began and then spread throughout the complex. On Nov. 5, it entered a new phase devoted to identifying the companies and decisions that made the disaster possible, as well as recommending ways to make sure a repeat never happens. To bring you up to speed, here’s a summary of recent developments.

*  Sir Martin Bick’s report on Phase 1 of the investigation concluded the disaster began not long before 12:54 a.m., when the resident in a flat on the fourth floor of the housing complex reported a fire in his kitchen that was started by an electrical fault in a refrigerator-freezer. “A kitchen fire of that relatively modest size was perfectly foreseeable,” the report said.

*  The first firefighters arrived about 1:09 a.m. and began entering the building. But by 1:14 a.m.—before they could reach the flat—the kitchen fire’s hot smoke caused a window jamb made of PVC to buckle and collapse,. That produced “an opening into the cavity between the insulation and the [aluminum composite material] cladding panels through which flames and hot gases could pass,” the report said. Pick believes this is the most likely way that the fire’s flames began igniting exterior cladding, starting a rapid ascent of the building’s east facade.

*  The ACM panels were part of a refurbishment in 2015-16 of the building, which was completed in 1974. They were meant to make the building warmer and drier.

*  Within an hour, flames were traveling across the north and east sides to the western and southern facades. It took fewer than three hours for the fire to engulf the 24-story apartment building.

*  “The principal reason why the flames spread so rapidly up, down, and around the building was the presence of the ACM rain screen panels; with polyethylene cores, which acted as a source of fuel,” the report said. “The principal mechanism for the spread of the fire horizontally and downwards was the melting and dripping of burning polyethylene from the crown and from the spandrel and column panels, which ignited fires lower down the building. Those fires then traveled back up the tower, thereby allowing the flame front progress diagonally across each face of the tower.” Polyiscyanurate (PIR) and phenolic foam insulation boards behind the ACM panels, as well as possibly components of the window surrounds, contributed to the fire’s spread.

*  Regarding those window surrounds: When the building was refurbished, the windows were moved outward so that they no longer set flush with the original concrete wall but rather with the new cladding system. This alteration “created certain weaknesses,” Bick said, in particular because the use of uPVC near combustible insulation helped the kitchen fire escape into the cladding.

*  Key fire protection measures and design elements failed. Extractor fans in the kitchens deformed and became dislodged, thus letting flames enter. Some fire doors didn’t work. Some left open had failed to close because they lacked effective self-closing devices.

*  “Compelling evidence suggests" that not only did the external walls fail to meet 2010 building regulations by resisting the fire, “they actively promoted it,” the report states. “Then it added: It will be necessary in Phase 2 to examine why those who were responsible for the design of the refurbishment consisted that the tower would meet that essential requirement.

*  The report declined to recommend changes to the testing and certification of building materials, but did say “there are grounds for thinking that the current regime for testing the combustibility of materials and cladding systems, particularly those chosen for use in high-rise buildings, may be neither as rigorous nor as effectively enforced as it should be.”

*  The report suggested Phase 2 investigators look not only into the choice of ACM panels but also the XPS window infill panels. In addition, the report questions why the design incorporated many vertical channels as well as an architectural crown composed of ACM fins.

*   Most of Bick’s recommendations involved London’s fire and rescue services, though he did recommend a speedup of work nationwide to remove panels with polythelyne cores from the exteriors of high-rise buildings. Meanwhile, owners should check whether combustible materials in their buildings’ cladding happen to be near kitchen windows.

*  Initial testimony during Phase 2 produced damning testimony alleging the manufacturers of three products that were crucial in spreading the fire intentionally tried to keep quiet evidence suggesting their products weren’t as fire-resistant as they claimed. Also, questions were asked whether the architect involved in the refurbishment should have hired a specialist fire consultant.