The fire at the 18-storey Torre del Moro in Milan in late August – which ripped through the exterior cladding of the building – was “a disaster waiting to happen” and shared many of the features of the blaze at Grenfell Tower, according to a preliminary report by a chartered building and fire engineer.
The Torre del Moro was a striking-looking residential tower completed in 2011. It consisted of a rectangular structural core, with curved ‘sails’ made up from lightweight steel attached to the long sides of the building. Located between the sails and the core were balconies, the decks of which horizontally divided what would otherwise have been an open space between the outer walls of the core, within which the living accommodation is contained, and the inner wall of the sails.
Credit: CesareFerrari/Alamy
Frances Maria Peacock’s report says the fire at the residential tower on 29 August could have been caused by an electrical short circuit in a flat on the 15th floor, though the cause and origin of the fire are still under investigation. It then spread to the balcony from where, due to the proximity of an abundance of ACM (Aluminium Composite Material) cladding, the fire took hold in minutes. The fire also quickly spread downwards and sideways, eventually destroying the entire sail and affecting the cladding on the structural columns, which extended up the full height of the building. Combustible material at roof level and the intensity of the heat enabled the fire to spread to the sail on the opposite side of the building.
Fortunately there were no casualties as all the residents were quickly evacuated and – it being a Sunday in summer – many residents were elsewhere.
The design and position of the sails also provided recesses that helped the fire spread rapidly up and down the building. The interfaces between the core and the sails created “introverted corners” which, says the report, “influenced fire spread”. Gaps at the first floor where the sails were constructed around a podium could also have contributed to a chimney effect.
In addition, the cladding was fixed around the four structural columns which went up the full height of the building which, says the report, could have helped the vertical spread of fire.
The cladding on the ‘sails’ was of a similar type to that at Grenfell Tower, consisting of an aluminium skin and polyethylene (PE) core. Again as was the case at Grenfell Tower, an alternative product which had a fire resisting core was not used. The cladding panels on the Torre del Moro made up extensive and interrupted vertical bands of cladding.
The walls at the ends of the building, however, were covered with an insulated render system containing limited combustibility mineral wool insulation. While fire spread up and down the building rapidly, the report says the fire could have been even worse had the ends of the building been clad in combustible ACM cladding. In addition, it’s thought that the separation of the cladding from the outside walls of flats by the presence of balconies meant that unlike the Grenfell Tower fire, the burning cladding was not directly around the edges of windows. This slight delay, says the report, may have been enough for people to get out safely before being impeded by flames and smoke.
The report concludes that “the tower was still affected by several shape-related fire phenomena, including fire spread in an upward, downward and horizontal direction as it followed the geometry of the cladding. Corner influenced fire spread, as well as a tendency for the flames to follow the line of the cladding at roof level, intensified the fire and helped it to spread to other parts of the building.”
To request a copy of the report email: [email protected]
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