Cladding tests
In the recent FPA/RISCAuthority study looking at the implications of penetrating (legal) rainscreen cladding systems with legally unfirestopped plastic vents (the external envelope of the building is not considered a fire compartment bounding wall), it was found that enough toxic products entered through a 100mm kitchen vent into an occupied 50m3
room to cause incapacitation and
possibly death within ten minutes of the fire breaking into the part of the cladding housing the vent.
All of this occured without breaking into the occupied space – an external fire internal to the cladding system. How does this scenario figure with ‘stay put’ policies? Toxicity is a complex area. The FPA work demonstrated graphically the need to burn the materials with accuracy if you are to truly understand the toxic threat. The degree of ventilation is crucial – burning the same insulating material in the open poses a very different toxic threat than would be achieved if burning in the underventilated confines of, for example, a cladding system void. There seems to be a growing desire within Europe to open up the debate on fire toxicity in the built environment, greatly added to by other
worrying studies on the long term cancer causing toxins in soil following major fires, and indeed the result of firefighter exposure to these over their careers.
Material participation
In this respect, debates around ‘combustibility’ are unhelpful – we all need to be talking about material ‘participation’. Some materials do not natively burn; if they do, this can often be adjusted by the use of fire retarding agents, but what if that simply exchanges a burning threat for a toxic threat when fire acts upon them – is that an OK thing to do? The answer is that it is, if it’s not measured.
Surely it’s time for a more balanced view on the total threat materials pose to occupants – especially for those who by merit of the complexity of the environment they occupy, or constraints on their own physicality, might just need more protection from what at the end of the day is the biggest known killer in fire – smoke toxicity
Dr Jim Glockling is technical director of the FPA and director of RISCAuthority
The FPA is hosting a toxicity conference in London on Monday 30 March – you can find out more and register to attend online at
www.thefpa.co.uk
www.frmjournal.com MARCH 2020
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