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Seven years after 72 people were killed in a devastating fire in the Grenfell Tower, West London, governments around the world are still struggling to respond to the threat of combustible cladding on tall buildings.

A UK public inquiry into the fire which published its final report earlier this month - and a spate of recent building fires - have highlighted the global issue of its use on potentially millions of homes and offices.

The Grenfell Inquiry found that panels made from an aluminium composite material (ACM) façade, containing plastic components, installed on the Grenfell Tower during a refurbishment between 2012 and 2016 was the principal reason for the fire’s rapid spread.

The remains of the Grenfell Tower in West London. Photo: Adobe Stock

Other major building fires whose spread has been linked to the use of ACM panels include: a 2010 blaze at a 28-storey high rise apartment building in Shanghai, China in which at least 58 people died; a fire at the 21-storey Lacrosse building in Melbourne, Australia; a spate of 18 fires on high-rise buildings over the last 13 years in Dubai; and a blaze at a 14-storey luxury residential apartment complex in Valencia, Spain earlier this year which killed ten people.

“Safety of people in the built environment depends principally on a combination of three primary elements – good design, the choice of suitable materials and sound methods of construction, each of which depend in a large measure on a fourth, the skill, knowledge and experience of those engaged in the construction industry,” said Grenfell Inquiry chair Sir Martin Moore-Bick. “Unfortunately, as our investigations have shown, at the time of the Grenfell Tower fire there were serious deficiencies in all four of those areas.”

The fires have prompted calls by Grenfell survivors and others for a global ban on combustible materials being used on all external wall systems.

But for construction professionals and governments around the world seeking to prevent a similar tragedy happening again, working out exactly which products to outlaw and under what circumstances, as well as establishing which existing buildings could be under threat, is proving to be a gargantuan task.

From the 1980s, a drive to cut heating costs and carbon emissions, encouraged architects and builders to encase structures in cheap and widely available insulating panel systems. With a mirrored surface of shiny aluminium, the insides of these aluminium composite (ACM) panels often included flammable plastics like polyethylene.

In his report, Sir Martin points out that even before the fire broke out, combustible cladding systems were already banned for use on tall buildings in some countries around the world including France and Germany (although there are still reports of combustible cladding panels being used on tall buildings in both countries).

Why isn’t there a global ban on combustible cladding systems?

Others, however, including the UK, Australia and Spain, took a different approach, based more on the functional requirements of each building and only took steps to ban flammable cladding and insulation panels from tall buildings following the disaster (see box).

With non-combustible panel systems looking pretty much the same from the outside as those which pose a threat, one of the major problems for building owners and public safety officials is establishing which of the thousands of buildings built before these law changes are still covered in panel systems which no longer meet safety standards.

As well as the potential fire risk, the issue has caused additional strain for flat owners who find themselves unable to sell or mortgage their properties. Tenants and freeholders argue over who should pay for the extensive and costly remedial work.

Guillermo Rein, a fire science professor at Imperial College London says that many countries have not even started identifying buildings which contain ACM cladding due to fears about the costs of remediation and worries about what the information could do to local housing markets.

Protestors hold a ‘Grenfell Never Again’ banner. Photo: Adobe Stock

“The situation is complex but the worst that can happen is that nothing is done about it,” he says. “Flammable ACM buildings must be identified worldwide soon, with a sound plan to bring extra safety to them while meaningful recladding work is arranged.”

Going forward too, countries are having to work out how to ensure that those building or refurbishing future towers understand the true level of risk of the materials they choose.

Although panel manufacturers have always tested their products to ensure that they met fire-safety standards, the Grenfell Inquiry heard that “systematic dishonesty on the part of those who made and sold the rain screen cladding panels and insulation products,” meant that pre-Grenfell, the results were often obfuscated.

Moreover, under pre-Grenfell arrangements, fire safety engineers would typically not be consulted over the design and construction of a façade, with most signed off via desktop assessments.

“Although we recognise that some changes have been made to the regulatory system since that time, we remain troubled by the fact that there is still no fire testing regime that delivers relevant information and by the failure to recognise the need for the application of competent professional judgement,” Sir Martin said. “We think a comprehensive overhaul of the fire testing regime needs to be undertaken together with initiatives that will improve the number of fire engineers capable of carrying out complex assessments.”