NFPA Journal - September/October 2017 - 39

wants to use it. The hope is for the tool
to serve as a springboard for fire and
life safety experts as they become more
involved with the issue, since a large
part of the problem is an uncertainty
that exists worldwide surrounding the
prevalence of combustible exterior wall
assemblies. "There's a need to look at
the attributes of these different systems and come up with an organized
approach, on a risk basis, for determining how an AHJ or a municipality
might evaluate the existing building
stock," said Harrington, a member of
the project's technical panel.
In the U.K., at least, the picture is
becoming clearer, thanks to the activity
prompted by the Grenfell fire. According
to a recent ABC News feature, at least
600 buildings in Britain are thought to
have an exterior wall assembly similar
to the one Grenfell had. Elsewhere, such
as Dubai in the United Arab Emirates,
the problem is also apparent. When
the 63-story Address hotel in downtown Dubai caught fire on New Year's
Eve 2015, onlookers captured stunning
videos of the flames shooting up the
tower's façade in a matter of minutes.
Five similar fires involving combustible
exterior wall assemblies have occurred
in Dubai since 2012. Two of those fires
involved the same building-a 79-story
residential tower named "the Torch"-
which suffered extensive damage after
flames shot up its sides in 2015 and
again in August of this year.
A 2014 FPRF report on combustible
exterior wall assemblies illustrated how
the problem extends to all corners of
the globe. The report identified fires
involving combustible exterior wall
assemblies dating back to 1990 in Australia, Canada, China, France, Germany,
Hungary, Japan, Russia, South Korea,
the United Arab Emirates, the U.K., and
the U.S. "It's certainly not a problem
unique to the U.K.," Harrington said.

REUTERS

An imperfect model?
On June 24, The New York Times published an article that posed the question,
"why did Grenfell burn?" It's a simple
question whose answer lies in decades
of failed policy changes.
The Times revealed that as far back as
1999, firefighters and engineers warned

Parliament that British building codes
weren't sufficiently written to address
the risk of vertical fire spread on buildings with combustible exterior wall
assemblies. Industry proponents pushed
back against the warnings, though,
and no code changes were made. Consequently, high-rise buildings with
combustible exterior wall assemblies
are thought to be widespread in Britain,
as evidenced by the scramble now to
inspect buildings similar to Grenfell.
With stricter building codes than
the U.K., the United States is often
thought to be a model for properly
vetting exterior wall assemblies. That
doesn't mean fires involving exterior
wall assemblies don't occur in the U.S.
In fact, of 32 exterior wall fires in highrises worldwide that were reported by
various news sources from 2014 to June
28, 2017, nearly half occurred in the

U.S. But few were severe, mostly occurring on assemblies that were added for
aesthetics and did not pose apparent
threats to the buildings. 
On the surface, the absence of severe
exterior wall assembly fires in the U.S.
seems like a testament to the successes
of North American codes and standards
like NFPA 285, Fire Test Method for
Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing
Wall Assemblies Containing Combustible Components. NFPA 285 outlines
a rigorous full-scale testing procedure
for exterior wall assemblies, and in
practice prohibits assemblies like the
one on Grenfell from being wrapped
around high-rise buildings.
Dig deeper, however, and questions
arise as to whether NFPA 285 is being
followed correctly and if the U.S. could
in fact experience a fire like Grenfell.

Combustible Components

Exterior wall assemblies exist in a range of configurations, but many include the
same elements found on London's Grenfell Tower
AIR GAP
In many assemblies using
insulation board and MCM
panels, an air gap exists
between the two components,
which in a fire can aid in
funneling flames up the sides
of a building.
METAL COMPOSITE
MATERIAL (MCM) PANELS
Aluminum is a common metal
used for MCM panels, which are
often referred to as "cladding."
In combustible exterior wall
assemblies, a plastic like
polyethylene is sandwiched
between two thin metal sheets
to create the MCM panels.
FOAM INSULATION BOARD
An insulation layer is applied
directly to the building's exterior
wall. Commonly used plastics like
polyisocyanurate, believed to have
been used on Grenfell Tower, are
cheaper than insulating materials
such as rock wool or glass wool
but are combustible.
N F PA . O R G / J O U R N A L * NFPA JOURNAL

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Table of Contents for the Digital Edition of NFPA Journal - September/October 2017
