SUMMARY. The various products used in the facade during the renovation of the Grenfell Tower in 2015-2016, begin to be known. Composite panels, polystyrene, polyethylene or polyisocyanurate, implementation… Batiactu is the point on the solutions employed during the isolation by the outside of this tower, which is burning in the night of 13 to 14 June 2017, making nearly 80 victims.
For different experts, there is no doubt that the exterior insulation (EIFS) in place on the tower Grenfell during its renovation in 2015-2016 participated in the rapid spread of the disaster that has ravaged the night of 13 to 14 June. But what were the products used in the facade ? Batiactu book the last items collected.
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Initially, in the first hours after the disaster, the sources speak of a composite liner and aluminum and a thermal insulation. Relatively waves that could cover a number of realities. The next day, the Construction Enquirer explains that the siding, these panels aesthetic reported in the facade was made of aluminum and synthetic insulation type polyethylene. An architect, quoted in the media uk, also touched on the possibility of a blank space between the panels and the walls of the building, necessary to ventilate the together to combat the humidity which is detrimental to the insulation and reduces their capacity. A void that would create, in the event of a fire, a real chimney, aspiring vertically from the flue gas and spreading the flames throughout the building’s façade.
On Thursday 15 June, the trademark Celotex (acquired by Saint-Gobain in 2012) has published a statement on its website, which states : “Our records show that a product Celotex (RS5000) has been ordered to be used during the renovation of the building. The technical data complete of all of our products are available on our website. If necessary, we will respond to the requests of the competent authorities, at the appropriate time. Given the evolving nature of the situation, it would be inappropriate for us to comment or speculate more about this tragedy“. The product in question turns out to be an insulating polyisocyanurate (PIR) used for buildings of a height greater than 18 metres. Of a thickness of 50 to 150 mm depending on the performance sought, it displays a lambda 0,021 W/mK, and has screens aluminum textured with very low emissivity.
The next day, Friday, the 16th of June, the company completes its statement : “It is important to note that Celotex manufactures only panels of rigid insulation. We do not produce, do not provide, nor do we install siding. The insulation is only one component of a system of rain screen, and that it is positioned behind the material of the cladding“. A little further on, the manufacturer ensures that his product is class 0, which corresponds to the highest resistance to fire, and that the component has been tested according to british standards (BS8414-2:2005). He argues that if it is used correctly, it meets the criteria of the report of the British Research Establishment entitled : “Performance in fire of the thermal insulation of the exterior walls of buildings of multi-storey”.
… and a cladding composite
The siding used, it would be of type Reynobond PE, according to the data revealed by the BBC and the Guardian. It is a sandwich of polyethylene (PE) sandwiched between two aluminum plates which he comes to bring strength and rigidity. An entry-level product range, recommended for buildings of low height, a lower elevation of 10 metres (R+3). According to the data provided by the manufacturer Arconic, the fire resistance of the product meets all regulatory requirements. But the range includes versions called “FR” for Fire Retardant, the performance of which fire would be improved, and even the “A2” to the towers of over 30 meters, that would be completely fire-resistant. The issue would therefore be one of the selection panels, unsuitable for a housing tower of 60 meters.
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The use of lacquered aluminum, lightweight and aesthetic, could therefore have had an impact on the place of the events, since the metal bottom from 660 °C, a temperature widely exceeded during a disaster, where the 1,000 °C are reached. The fire behaviour of the core of the panels, low density polyethylene, non-treated, also raises question. The presence of an air gap between the exterior panels and the insulation polyisocyanurate set in front would, in turn, accelerated the spread of flames. During fire tests organised at the european pole of security CNPP Vernon, in the Eure, Batiactu had found that this insulation exhibited a certain resistance to the fire, of the order of 10 to 20 minutes, superior to that of expanded polystyrene. A time that the fire department considered it sufficient to give them time to respond on the claim. But, as we explained to the supporters of the rock wool, “this material is the tendency to generate harmful fumes, including hydrogen cyanide, much more toxic than carbon monoxide“. A problem that would come, therefore, to complicate the work of firefighters british and that would have left little chance to the residents of the tower, Grenfell.
As often in the long history of disasters, this fire murderer would therefore be the coordination of a variety of factors : signs that are inappropriate for IGH, an insulating material that generates toxic fumes, an implementation process that tends to facilitate the spread of fire to the upper floors… An exceptional situation that the british authorities are seeking not to reproduce.