25.04.18
‘Utter inadequacy’ of fire safety tests exposed
Research carried out in the wake of the Grenfell Tower tragedy has exposed the “utter inadequacy” of the laboratory tests currently used to check the safety of building materials.
The Association of British Insurers (ABI) commissioned the Fire Protection Association (FPA) to carry out a series of controlled experiments in which building conditions, more realistic than those in standard tests, were recreated.
The reason was to measure the difference that these factors could make in the event of a real fire.
According to the ABI, a number of real-life factors are overlooked by the official testing regime.
In modern blazes, around 20% of the materials involved are plastic, but the ABI revealed test fires are only made up of wood.
Where two fires with these different compositions were compared, the fire containing plastic had longer flames and temperatures over 100 degrees hotter than the fire made only of wood.
The temperature was still increasing when it had to be extinguished because it was exceeding lab safety conditions.
The ABI warned that this means that plastic-containing fires can spread faster, and the higher temperatures can cause building materials such as aluminium to lose much of their strength; much cladding, including that used on Grenfell Tower, is made up of aluminium composite panels.
Cladding materials are sometimes tested as a sealed unit, whereas when they are fitted on a building they very often include gaps and cover a much more extensive area.
Test fires on units with no cladding or sealed cladding climbed to around 1.5 metres before running out of oxygen and self-extinguishing.
However, the fire in a unit with cladding gaps rapidly spread up the entire six metre height.
Additionally, materials are tested in manufacturer conditions, whereas during their actual use they will often be pierced by things such as vents or ducts.
Tests on a section of cladded wall with a plastic vent installed indicated that this was an “almost instantaneous” route for the fire directly into the void between the wall and the cladding.
The ABI warned that fire safety often relies upon assumptions about how long a fire will take to penetrate certain areas of the building, but that fittings such as these can make a big difference to how materials perform.
In its submission to the Hackitt review, the ABI called for all materials used in construction to be non-combustable, as well as a reformed testing regime that replicates real world conditions.
It says that the results of these latest tests reinforce the importance of an urgent reform.
Last week, a report leaked to the London Evening Standard revealed that the cladding material was combustable and that there were “deficiencies” in the construction of the façade.
As a result of Dame Judith Hackitt’s recommendations in her interim report on the review of building regulations and fire safety, the government is currently consulting on whether “desktop studies” should be banned or restricted.
Huw Evans, director general of the ABI, said: “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.”
Jonatan O’Neill, manning director of the FPA, said that the research confirms long-held concerns that the current cladding test standards require urgent review.
“We urge 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,” he added.
Top image: Victoria Jones PA Wire
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