For the past decade, engineers specializing in fire safety have worried about the hidden danger posed by the kind of insulated metallic skin that transported flames up a highrise apartment building in London, killing dozens.
Panels of the armourlike ‘cladding’ have become a popular facade on tall buildings worldwide, both for their sleek look and energy-saving virtues.
But they also have helped fuel spectacular infernos in the Middle East, Europe, Asia and the United States.
Some fire experts worry that, with energy efficiency a priority worldwide, the proliferation of ‘green’ buildings has the unintended consequence of fanning fire danger.
Though cladding can be flame-resistant, the result can be deadly when it is not.
‘The good intent of sustainability translates into a potential fire safety problem,’ said Brian Meacham, a fire protection engineering professor at Worcester Polytechnic Institute in Massachusetts. His concerns began to crystalize in 2010, he said, when he was in South Korea presenting a paper on new technology and fire safety and a cladded highrise burned.
At London’s Grenfell Tower, flames raced with alarming speed up 24 stories of cladding in which a plastic core was sandwiched between thin sheets of aluminum.
That composite is one of several kinds of exterior panelling that helps moderate inside temperatures, saving on energy needed for heating and cooling.
The tower’s aging concrete facade received the facelift last year as part of a $13-million publicly-funded refurbishment effort aimed, in part, at making the building more energy efficient.
The tower, home to as many as 600 people, burned Wednesday. At least 58 people are confirmed or presumed dead, a tally that could rise.
Authorities are still investigating the fire. Its behaviour strongly implicated the cladding, several fire safety experts said in interviews. Anger has mounted in the community following reports that contractors had used cheaper panels in which the plastic insulation was not fire-resistant.
Cladding with pure plastic insulation costs less and insulates better than an alternative that incorporates fire-slowing minerals, experts said. On short buildings, it makes sense.
Not so for taller buildings.
The International Building Code — a model of construction standards adopted widely in the United States, some areas of the Middle East and the Americas — calls for the use of fire-resistant cores in buildings over 12 metres tall.
The code in England is less specific, giving architects latitude in how they make sure exterior insulation is safe as long as ‘the external walls of the building shall adequately resist the spread of fire.’
Two British government officials — Trade Minister Greg Hands and Treasury chief Philip Hammond — said in separate TV appearances Sunday that the cladding used on Grenfell seems to be prohibited by British regulations. Hands cautioned that officials don’t yet have exact details about the renovation.
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