An inquiry into the lethal Grenfell Tower fire has found that the building failed to meet building regulations following a major refurbishment in 2015-2016.
According to the 1,000-page report published by Martin Moore-Bick, insulation, cladding and decorative fins added to the building during its refurbishment made it noncompliant with the UK's Building Act 1984 and Building Regulations 2010.
“There was compelling evidence that the external walls of the building failed to comply with Requirement B4(1) of Schedule 1 to the Building Regulations 2010,” reads the report.
“They did not adequately resist the spread of fire having regard to the height, use and position of the building. On the contrary, they actively promoted it.”
According to the Building Act 1984 and the Building Regulations 2010, external walls should be able to resist the spread of fire, and alterations made to existing buildings should not affect the building's compliance.
A lethal renovation
When the building was renovated from 2015-2016, aluminium composite material (ACM) rainscreen panels with a polyethylene core and insulation panels consisting of polyisocyanurate (PIR) foam were used to construct a new exterior wall around the existing reinforced concrete walls.
Experts have deduced that on 14 June, 2017 when fire spread through Grenfell Tower, it likely reached the cladding through a hole that formed when hot smoke from a refrigerator fire caused the uPVC window jamb to deform. The fire then reached the combustible insulation materials around the window frame before travelling to the ACM panels.
PIR and phenolic foam in the insulation boards behind the cladding were another contributing factor to the rate and spread of the fire.
The fire was worsened still by exposed polyethylene in the decorative crown that topped the tower, which melted and dripped as it burned, causing additional flames to take hold further down the building, which proceeded to spread back upwards. The fire then spread throughout the building until it lethally reached the inside.
Fins of cladding had been added to the precast concrete crown purely for decorative purposes. Expert witness architecture professor Luke Bisby says this caused the crown to act like a "linear fuse" for the fire, spreading it horizontally.
According to the report, gaps were also purposely left between the new wall of cladding and insulation and the concrete wall as ventilation and anti-moisture measures. However, these gaps meant fire was able to spread easily to the cladding.
While cavity barriers with strips to prevent fire had been installed, they were poorly fitted and not airtight. According to experts however, even if these barriers had been installed properly there was little they could do to quell the fire once it had reached the ACM panels.