The general consensus in the media is that the London fire catastrophe in the Grenfell Tower couldn't happen in the US because of our stricter fire codes which don't allow highly flammable insulation material on facades without fire retardents and certainly no high-rise building with a single exit stairway. While it is true that US standards are stricter on both of those counts, there remain troublesome aspects of the London fire that should give architects, engineers, and building managers involved in multi-family housing pause as they deal with egress and flame spread .
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Grenfell Tower fire, London |
There has been a slew of sometimes spectacular facade fires on highrises which may not have had the terrible death toll of the London fire, but certainly caused very hazardous conditions and large property damage. Those fires happened mostly abroad, but not always: The huge fire on the Marina Torch, Dubai, February 21, 2015, the fire on the Grozny-City Tower Hotel, Grozny, Chechnya, April 3, 2013, and the Tamweel Tower fire in Dubai, November 18, 2012. There were also prominent facade fires caused by foam insulation in the US, both in casinos that were found to have used non code compliant construction. (The Monte Carlo casino façade fire in Las Vegas, NV, in 2008 and the the Water Club Tower fire at the Borgata Casino in Atlantic City, NJ, in 2007.
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Overall, the IBC identifies each major category of combustible component in an exterior wall, and provides detailed limitations and allowances for each type. For each such combustible component, there are typically individual component requirements, such as ASTM E84 flame spread index limits and ASTM E1354 cone calorimeter heat release limits. Making compliance easier, each section also includes several exceptions and exemptions. For example, NFPA 285 compliance is exempted for combustible exterior cladding that is installed not higher than 40 feet above grade. (Source)
1. The InsulationThe London highrise had been subject to a insulation retrofit which is not uncommon in the US either, notably because of the increased insulation requirements of the 2007 edition of ASHRAE 90.1 "Energy Standard for Buildings Except Low-Rise Residential Buildings," as well as the 2006 and 2009 editions of ICC's International Energy Conservation Code. Both require significantly increased R-values for exterior walls in almost all states of the country.
The most typical method of increasing the R value of the extreior wall is the use of "continuous insulation across all structural members without thermal bridges other than fasteners and service openings. The easiest way to accomplish this is to install continuous insulation on the exterior side of the exterior walls by using noncombustible mineral wool or combustible foam plastic insulation such as extruded polystyrene foam, expanded polystyrene foam, polyisocyanurate foam or spray-applied polyurethane foam.
Archplan Inc. Philipsen Architects