RICHARD HULL, PROFESSOR OF CHEMISTRY AND FIRE SCIENCE AT THE UNIVERSITY OF CENTRAL LANCASHIRE

One of the things that still seems to be in circulation is the myth that PIR doesn’t burn.

If you go online you will see videos saying it doesn’t burn.

Working with the Panorama programme (May 21 2018), we held a Bunsen burner under a piece of aluminium composite material (ACM) filled with polythene and the molten drips ignited the PIR straight away.

In my opinion, when you replace brick, stone or concrete with combustible materials, you are compromising the integrity of the building.

If there is a fire, the contents of the building usually burn, because it is too difficult to control what is put into a building, but if the fabric of the building also contributes to the fire, that it when it leads to disaster.

If you put insulation panels and a membrane above a concrete roof, the concrete would probably stop the fire spreading back down through the roof.

If you don’t have a concrete roof there isn’t anything to stop the PIR adding to the fire load.

If the fire is in the roof it will tend to spread only upwards, not downwards, but if it opens up the space below, more oxygen will get in and the fire will grow much more quickly.

If there was a fire in the V&A in Dundee and it spread to the roof the PIR could ignite, turning the fire into an inferno.

Putting PIR on the roof adds a lot more fuel to the building and may compromise its integrity, allowing more oxygen to get in.

When ignited, PIR foam insulation gives off toxic gases, including hydrogen cyanide and carbon monoxide, which cause rapid incapacitation when inhaled, preventing escape.

Hydrogen cyanide stops your body being able to use oxygen.

You could collapse within a minute or two but you probably won’t die until after about 30 minutes.

About 1 kg of burning PIR (30 x 30 x 10cm3) is enough to knock-out everyone inside a small flat (100 m3).