We’ve known about the kind of problems that happened at Grenfell Tower for years, so why has no one done anything about it? Some insulation companies have tried to do something about it, and much of the insulation used today has a high degree of fire resistance. As far as I know there is no legal requirement for all insulation sold in the UK to be fire retardant, and Irish regulations, for example, seem to be far stricter than our legislation here in the UK. You can get the same kind of fire retardant insulation in the UK as is shown in the Irish brochure on the link but here, it’s just a good idea. It’s not, as far as I’m aware, a legal requirement. I am surprised that the disaster in Grenfell Tower was caused by a fridge catching fire, which had been put out by the fire brigade, and the heat from the fire travelled through a half inch concrete panel and a two inch air gap where it set fire to the insulation. News reports have also said that Grenfell Tower was not fitted with insulation of particularly good quality and it was not designed for a tall building. We fit new houses and refurbished buildings with so much insulation, nowadays. Should we be worried?
Some insulation materials are naturally fire resistant and others can be made fire resistant by adding a small amount of fire resistant material. Polystyrene insulation (EPS) has very poor fire resistance but is better if, like most modern insulation, it has a fire retardant added to it. Is a product designed as external wall insulation made from EPS a suicide policy? Not necessarily. It would probably contain a fire retardant. PIR and PUR (polyurethane foam) have reasonable fire resistance and phenolic foam has a high fire resistance. In recent years PIR, PUR and phenolic foam insulation have become available in fireproof grades, meaning that a fire retardant has been added to the material to increase its fire resistance still further. Mineral wool has a very high fire resistance.
Manufacturers test insulation by setting fire to a wall made out of wooden joists with insulation boards positioned in between the joists. Imagine putting insulation in your loft and setting your roof on fire. An timber frame wall has a very similar construction to an ordinary house roof. The time it takes the insulation to catch fire is measured. Polystyrene insulation (without fire retardent) catches fire in a few minutes. PIR insulation takes 30 minutes. Pheonlic foam insulation takes 50 minutes. Mineral wool takes between one and two hours to catch fire – the exact figure varies from one manufacturer’s test to another. All insulation would burn eventually, it’s fire safety is relative to how long it would take to burn.
Many items in a building are designed to burn slowly, in order to give people time to get out in the event of a fire. By law, a firebreak in the roof between two houses needs to take half an hour to catch fire, and so does a fire door. Fireproof grade plasterboard works in the same way. Insulation that takes 50 minutes or over an hour to catch fire allows for more time to evacuate a building. This is especially important in flats, where a fire in one flat is very likely to spread to another. All parts of a building will burn in a severe fire, and in a block of flats or a house of multiple occupation expert advice should be taken from the fire brigade and the firm who install the fire alarms. Fire resistant insulation should be used but understand this as part of a larger safety strategy, including evacuation plans, smoke alarms, central fire alarms and possibly sprinkler systems.
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