Cladding focus
regard to the height, use and position of the building.’ Therefore, neither of these materials – especially when coupled with the lack of fire barriers detailed in the advisory provisions of the Building Regulations – should have been used in this system, regardless of the building’s height. The images in Figures 3 and 4 (see p44) show a vast empty cavity behind a high pressure laminate (HPL) rainscreen cladding system; behind the grey breather membrane was an 80mm thick phenolic foam insulation. This view looks down towards the ground, and the light seen at the bottom of the cavity is four floors below the survey location. As can be clearly seen, no cavity barriers have been installed to contain the spread of a fire up this chimney, which also stretched two floors above the survey location. Furthermore, the system would not meet Building Regulation B4(1) for the same reasons outlined under the previous images. Finally, when the Ministry of Housing,
Communities and Local Government (MHCLG) published Advice Note 22 following a series of tests on HPL cladding, which has now been superseded by a consolidated advice note dated 20 January 2020, it confirmed that its expert panel had ‘not been presented with any evidence of an HPL panel of any class achieving the performance criteria set out in BR 135 when used in combination with combustible insulation’. The document also states: ‘Building owners who have Euroclass
C-s3,d2 or D-s3,d2 HPL panels on residential buildings under 18m should also consider the risk from fire spread and consideration should be given to ensuring the overall intent of Requirement B4 is being met irrespective of building height.’
Other materials
The government recently released a series of test results undertaken on other materials, which concluded that they did not burn at the same rate as the polyethylene cored aluminium composite material (ACM) used at Grenfell. However, there has been criticism that the materials were tested in isolation rather than as realistically installed, with varying insulation products and a rainscreen type cavity. The materials tested did not include timber or expanded polystyrene. Of course, ACM cladding has received the most publicity since the tragedy of Grenfell, which has been supplemented by advice on spandrel panels and HPL cladding. However, we feel that further education is still required for responsible persons regarding other products which are just as combustible. Expanded polystyrene, phenolic,
polyisocyanurate and polyurethane insulations are all extremely combustible, and can assist the spread of a fire even behind external cladding panels of limited or no combustibility – especially if the system is poorly compartmented, designed
FOCUS
Figure 1
Figure 2
www.frmjournal.com JUNE 2020 43
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