Fire safety testing regime 'requires urgent review'
TESTING RESEARCH undertaken by the Association of British Insurers (ABI) and the Fire Protection Association (FPA) have ‘exposed the utter inadequacy’ of current building material fire safety tests.
The ABI reported on the test programme undertaken by the FPA on its behalf, with the ‘carefully controlled’ experiments aiming to create ‘more realistic building conditions than those in which the standard tests are done’, in order to ‘measure what difference these factors could make in the event of a fire’. It stated that the research ‘has exposed the utter inadequacy’ of the current tests used ‘to check the fire safety of building materials’.
This testing programme saw the FPA study ‘real-life factors overlooked by the official testing regime’, including test fires that are ‘only made up of wood’, when modern blazes feature ‘around 20%’ plastic. It also looked at how cladding materials ‘are sometimes tested as a sealed unit, whereas when fitted on a building they often include gaps, and cover a far more extensive area’.
Finally, the programme analysed fires where ‘materials tested will be in manufacturer condition, but during their actual use will often be pierced by things such as vents or ducts’. When submitting to Dame Hackitt’s review of building regulations and fire safety, the ABI called for an ‘end to the use of all but non-combustible materials in construction’, alongside a ‘reformed testing regime that replicates real world conditions to provide genuine evidence of how materials perform in a fire’.
From its perspective, its test programme’s results ‘all reinforce the importance of urgent reform’, with the first test creating two fires ‘with the same energy content, one purely built out of wood, the other containing 20% plastic’. Flames created by the latter had a flame length ‘around 1 metre longer’ than the wooden fire, while its temperatures were 100 degrees hotter ‘and still increasing’ when it had to be extinguished because it was ‘exceeding lab safety conditions’.
This test’s implications were that ‘as well as the ability of the fire containing plastic to spread faster and create higher temperatures, building materials such as aluminium lose a lot of their strength at higher temperatures’, with ‘a lot of cladding’, including that used on Grenfell Tower, ‘made up of aluminium composite panels’.
The second test saw fires started at the bottom of three columns: one with no cladding or cover, another with cladding fitted ‘to create a void but with sealed edges and ends’, and another clad with a void, ‘leaky sides and some ventilation at the top and bottom’. Fire climbed 1.5 metres up the first ‘before burning out and self-extinguishing’; the second saw fire climb a similar distance ‘before it ran out of oxygen and self-extinguished’, and the third having ‘rapidly caught fire up the entire 6 metre height of the testing column’.
Implications of this included that the ‘availability of oxygen makes a massive difference to how materials respond to fire’, with well ventilated voids behind cladding seeing the ‘rate at which fire spreads’ potentially ‘greatly increased by a chimney effect’. Any tests restricting availability of oxygen ‘in a way that doesn’t happen on a full scale building will not be able to correctly assess how the materials will behave in practice’.
The final test meanwhile saw a section of wall and cladding set up with a plastic vent installed, as they are a ’common feature’, before a fire was started underneath. Temperatures inside the vent ‘indicated it was providing an almost instantaneous route for fire directly into the void’ between the cladding and wall ‘long before the time it would take fire to break through the outside cladding panels’.
The ABI pointed out that the implications here include that fire safety (in particular in high rises) often rely ‘upon assumptions about how long it will take fire to penetrate certain areas of the building’, with the presence of fittings likes vents potentially making ‘a big difference to how materials perform and how a fire will spread’, and as such ‘needs to be realistically modelled in testing’.
Further tests that examined the ‘real-life performance of cavity barriers’ and the ‘differences made by materials being unrealistically strengthened during the testing process’ were also undertaken, and were detailed in the full report. The ABI added that it has provided the research ‘in full’ to Dame Judith’s review.
Huw Evans, director general of the ABI, stated: ‘Dame Judith Hackitt’s important work post-Grenfell has already recognised the building control system is broken. This latest research is yet more evidence that fundamental reform is needed to keep our homes and commercial premises safe from fire. It is a matter of urgency that we create the right testing regime that properly replicates real world conditions and keeps pace with building innovation and modern design.’
Jonathan O’Neill, managing director of the FPA, commented: ‘The results of this important research confirm long-held concerns by many in the fire sector that the current cladding test standard requires urgent review to ensure that systems that pass are reflective of the systems that are installed and of the risks to which they are exposed.
‘We urge BSI (British Standards Institution) to urgently reconvene the group responsible for this standard to consider the results of this research and to make changes to the standard as required.’