A fire in The Address Hotel in Dubai on New Year’s Eve has caused extensive damage, with unofficial estimates for the repairs and business interruption losses exceeding $100 million. Millions around the world saw the huge fire travel up the outside of the building and many have asked how this could happen. As far as we can determine, the building was fitted internally with sprinklers but not on the exterior balconies. The sprinklers worked, helping to prevent fire spread inside the building and any loss of life from what was a huge fire. All the reports indicate that the fire started on an exterior balcony and spread to the building’s combustible cladding. Until 2012 combustible core cladding, composed of cheap, lightweight insulating material such as polyethylene or polyurethane between sheets of aluminium, was widely used in Dubai.
While this sort of cladding can achieve a fire-resistant rating in some standardised fire tests, the core is combustible and if the fire gets into the core, for example through any holes in the aluminium layer, it can rapidly spread. The Address Hotel fire is not the first fire in this sort of cladding:
Baku, Azerbaijan, 19 May 2015 (15 deaths)
Marina Torch, Dubai, 21 February 2015
Grozny-City Towers, Chechnya, 3 April 2013
Tanweel Tower, Dubai, 18 November 2012
Polat Tower, Istanbul, 17 July 2012
La Tour Mermoz, Roubaix, France, 14 May 2012 (1 death)
Al Tayer Tower, Dubai, 28 April 2012
Sonacotra building, Dijon, France, 14 November 2010 (7 deaths)
Sprinklers inside a building cannot prevent a fire that starts outside the building from spreading into its combustible cladding.
They can help to prevent that fire from entering the building and the fact that nobody was killed on this occasion and a relatively small number of people received minor injuries is testament both to the performance of the sprinklers inside the building, and the response of the fire brigade. Some have suggested that sprinklers should be fitted outside buildings to protect the cladding. It is feasible, if expensive, to retrofit external balconies with sprinklers to control or suppress any fire that starts on a balcony. By contrast the sprinkler industry does not have a readymade solution for the protection of external cladding.
A better approach is to fit cladding with a non-combustible or weakly combustible core. In the US the relevant test protocol is NFPA 285. In the UK it is BS 8414. In the US the fire code is the IBC, which requires the cladding pass NFPA 285 if the building is higher than 40 feet (12.2 m). In the UK the reference is Approved Document B, which requires that « In a building with a storey 18 m or more above ground level any insulation product, filler material (not including gaskets, sealants and similar) etc. used in the external wall construction should be of limited combustibility. » An appendix explains in detail what is required.