Combustible Cladding in High-Rise Buildings: A Toxic Legacy from the Construction Industry

 The long-awaited, and much overdue, Phase 2 Report of the Public Inquiry into the Fire at Grenfell Tower, chaired by Sir Martin Moore-Bick, was released on 4 September 2024, concluding an investigative process that was set up by Prime Minister Theresa May on 15 June 2017. It was widely agreed that the 1,571-page, seven volume, report was comprehensive and well worth the wait.  The inquiry had entailed 312 days of public hearings, at times interrupted by the COVID-19 pandemic, and correspondence with 247 individuals and organisations. At the public launch, Sir Martin did not mince his words as he named and shamed the various organisations deemed to be responsible for the tragedy.

The overwhelming fire at Grenfell Tower, a social housing facility in London’s Royal Borough of Kensington and Chelsea-the richest borough in the UK-originated in a fridge-freezer in Flat 16 on the fourth floor. Its rapid and vertical spread was attributed to a cheaper form of cladding that was installed as part of a refurbishment exercise between 2012 and 2016 to improve the appearance of the tower block and to provide thermal insulation. The cladding system consisted of one or two layers of polyisocyanurate (PIR) foam, directly applied on to the original concrete wall. An air space separated this foam insulation from an outer layer of two thin flat sheets of aluminium composite material (ACM) rainscreen, with combustible unmodified polyethylene (PE) cores. The external cladding of Reynobond PE 55 panels was supplied by Arconic Architectural Products. This product was manufactured in France and sold by Arconic in the UK to CEP Architectural Facades, a specialist fabricator, who constructed three-dimensional cassettes, which were then installed by a sub-contractor, Harley Façades Ltd, as a protective rainscreen for the façade of the tower.  The PIR and phenolic foam insulation were provided by Celotex and Kingspan.

The fire spread vertically upwards and laterally along the cladding to engulf the building, facilitated by the melting, dripping, and burning PE cores. The effects of the fire at Grenfell Tower, which killed 72 people, including 18 children, were amplified by the lack of fire safety systems, such as smoke alarms, sprinkler systems, safety doors, ventilation systems, emergency lighting, and escape routes, and too few emergency exits, as well as by London Fire Brigade’s ‘Stay-Put’ advice to those trapped within.

Cladding is the external skin applied to buildings to improve their appearance and increase their thermal energy efficiency. It is non-load bearing, and is not directly responsible for the structural stability of the building. Cladding can form part of the design of a new building or may be retrofitted as prefabricated panels into an existing building, as at Grenfell. Cladding, in its simplest form, consists of front façade panels (made from wood, metal, brick, vinyl, or composite materials) and thermal insulating material (mineral wool, or phenolic foam). Cladding systems themselves can be rather complex constructions, incorporating such components as breather membranes, cavity barriers, vents, and so on.

Ideally, cladding should be non-combustible and resistant to fire. But ACM and HPL (High Pressure Laminate) panels, in wide use at the time of Grenfell, are combustible. Unfortunately, a preference for low- cost materials, and a failure of regulation in the construction industry have set the scene for multiple devastating fires in high-rise properties. The first tower block cladding fire in Britain was witnessed in April 1991, at Knowsley Heights in Huyton, Merseyside. The 11-storey block, with 64 flats, was wrapped in a flammable polymer cladding, separated by an air-filled cavity from an inner layer of wool insulation.  Eight years before the Grenfell tragedy, another fire in July 2009 at Lakanal House, a 14-storey tower block with 98 flats, in Camberwell, south London, was to provide some lessons concerning cladding and fire safety that seem not to have been acted upon.

The Grenfell Tower tragedy led to the commissioning of an independent review of building regulations and fire safety in September 2017. Dame Judith Hackitt’s review, Building a Safer Future-Independent Review of Building Regulation and Fire Safety, was published in May 2018 and confirmed what was either suspected or already known. She recommended clearer building standards and more effective regulation of the construction industry. In November 2018, the UK government banned the use of combustible materials on new high-rise buildings taller than 18 metres and containing more than one dwelling.

Meanwhile, at community level, dispossessed survivors and bereaved families, many from marginalised groups of the populace, formed Grenfell United to make their voices heard. This being a national crisis, by April 2019 the End our Cladding Scandal had brought together Grenfell United, Inside Housing, Manchester Cladiators, the UK Cladding Action Group, and other campaigns and charities. Communities have come together to campaign for remedial action in their areas. But progress where it matters most has been rather slow to arrive. According to government figures published in late August 2024, 4, 630 residential buildings in England, 11 metres and taller, have been identified to have unsafe cladding, but remedial work had only been completed by then on 1,350. Delays have been put down to controversies over who should shoulder the costs of remediation and to then find suitably qualified staff to set matters right. Government funding schemes such as the Building Safety Fund have had only limited impact on this difficult situation.

The Public Inquiry has identified the contributory issues for the Grenfell fire and apportioned blame accordingly. Its 59 recommendations are, however, discretionary and not legally enforceable. Any ensuing criminal proceedings will now have to be initiated by the police and conducted in the courts, constrained by the inevitable delays in the legal system. This brings little hope to homeowners who are trapped, from no fault of their own, in homes with unsafe cladding, lumbered with high insurance premiums, worried about their futures, and unable to move on with their lives. Judging from the pace of change, unsafe cladding will continue to be in the news for some years to come.

Ashis Banerjee