Strict standards
Canadian buildings meant to guard against fires like London blaze
Canadian building standards should theoretically prevent the sort of blaze that engulfed a London apartment tower earlier this week, but at least one expert says flouting those regulations can put people in serious danger.
Exterior panelling known as cladding that was recently installed on the 24-storey Grenfell Tower is increasingly being cited as a factor in the blaze that killed at least 30 people and left dozens of others still missing.
British engineering experts have begun speculating that the cladding was constructed of inferior, combustible materials that helped spread the fire rapidly up the building.
Engineers say cladding is a common and often necessary feature of buildings that is used to prevent moisture from seeping into the main structure.
Canadian regulations clearly spell out rules for cladding that can be used on buildings of at least four storeys in height and state that the material needs a fire rating of at least one to two hours – a window that would theoretically allow most people ample time to escape a blaze.
But Doug Perovic, a forensic engineer who teaches at the University of Toronto, says trouble arises when builders try to An emergency worker takes photographs from inside one of the lower floor windows of the fire-gutted Grenfell Tower in London.
cut costs by resorting to cheaper materials that don’t come up to code.
Most cladding, he explained, is composed of a metal skin, such as aluminum, and a core material that usually dictates its overall fire resistance.
“There are polymers, plastics out there that don’t burn,” he said in a telephone interview. “They’re going to be more expensive, and it can form the core of that kind of composite cladding. But if someone’s cutting corners and getting the cheaper stuff, which seems to happen in a number of these fires, you’ve got a potential problem.”
Media reports in the U.K. suggest that may have been the case in the Grenfell fire.
The Guardian reported that when the building was refurbished last year, it was finished with a cheaper form of aluminum composite cladding that did not contain fire-resistant material.
The Guardian also reported that the U.K. has no regulations requiring the use of fire-retardant material in cladding used on the outside of tower blocks and schools.
Such is not the case in Canada, according to the national building code.
All exterior cladding materials for buildings higher than four storeys must be tested for fire resistance and comply with strict standards.
The Canadian Commission on Building and Fire Codes, part of the National Research Council, updated its regulations as recently as 2015. The council did not respond to request for comment.
Leaving cladding off buildings altogether is not widely viewed as an option, since it can fulfil a key function by acting as a rain screen. Papers posted to the NRC website as far back as 1999 discuss the effectiveness of the “rain screen principle” and spell out how it works.