Grenfell Tower: Questions need to be answered
Independent building inspector Geoff Wilkinson explains how tower blocks like Grenfell Tower are meant to perform in a fire.
The fire at Grenfell Tower in Kensington, West London has been described as one of the worst domestic fires in modern times taking the lives of at least 12 people and injuring scores more. Given my experience, I too was shocked by the blaze which engulfed the tower in the early hours of Wednesday morning.
At this point in time it’s very hard to tell precisely what went wrong. We don’t know where the fire started and we don’t know how it spread. What we do know is there are scores of small fires in tower blocks around the country every year that are contained and with no spread of fire.
If regulations were followed, what happened at Grenfell Tower should never have been possible, and there are very big questions which need to be answered. What was it about this block that allowed the fire to spread so quickly?
The basics of fire regs strategy
Normally, British fire regulations assume that fires will start in one location only – and normally, this is completely reasonable. In a big tower block like Grenfell, each individual should be designed as a fire-tight box. That is why residents are usually advised to stay within their own rooms and wait for rescue.
Most residential blocks don’t have common alarms – as appears to be the case at Grenfell Tower – because they could trigger a mass panic in which everyone tries to evacuate via the same stairwell which the fire service are using to reach the fire. In the event that a fire grows too large, firefighters might sometimes decide to evacuate the floor immediately above.
What happened at Grenfell was something else entirely. Within half an hour or so it had travelled way beyond the first flat, making it very difficult for the fire services to control it. Even more worryingly, survivors have reported that stairwells and lobbies were choked with smoke, which should never happen: there are supposed to be means of clearing smoke from such areas. In those circumstances, “stay and hide” becomes obsolete.
Fire spreading through the cladding
In 1999 after a fire in a tower block in Irvine new regulations were put in place which limited the types of cladding which could be used and fire barriers were made mandatory at various points in the cavity, blocking off the “chimney” on all sides.
The Guardian has reported that some panels used in modern cladding are only fire-proofed on the surface, behind which is up to 30cm of highly flammable polyurethane. If true, that is a major non-conformance with regulations. But even if not, were the proper firebreaks put in place behind the panels?
Once spread via cladding, the fire could have caught on curtains blowing through windows left open on a hot summer’s night. Again this is believed to have been a factor in the Lakanal House fire in 2009. That disaster occurred on a very similar night to this one.
Fire compartmentation inside
Even if the fire spread inside the building should still have been safe. For the fire to spread internally after that point it would still have to get through the fire door in the individual room, through another fire door at the front of the flat, and through yet more doors in the corridor outside. Clearly there has been a failure of multiple systems: for one to fail is perhaps understandable, but for so many to have failed all at once, in the modern era, is entirely unheard of.
The investigation will of course look into this. But another explanation may lie in reports, as yet unsubstantiated, that works were recently carried out to the gas main that runs vertically up the building. If the contractors carrying out those works did not replace the necessary fire protection after finishing, that would be an easy way for fire to spread.
Anything that creates a path for fire can and will be used in that fashion. Even a drill-hole of four inches in diameter can be enough. And if there are combustible materials in ducts – plastic pipes, plastic wires – flames can creep rapidly through a building without the fire service even knowing.
The Lakanal House fire in 2009 led to specific recommendations. All landlords were given clear, copious information on fire precautions and told to undertake regular risk assessments. People like me then go around the tower blocks checking for ducts that need to be blocked or cladding that needs to be fixed.
The problem is that we never really know whether the works we recommend are actually carried out, or, if they were, how long they took. There is no easy way to check whether landlords have carried out their duty.
Worse, there is an ongoing issue around contractors who don’t understand what they need to do to ensure fire safety. Anyone who the landlord allows to alter or amend a building, in any way, shape or form, must be made aware of which walls are fire walls and which materials need to be replaced after they’re done. That, too, doesn’t always happen.
Nobody can turn around after Knowsley, Irvine and Lakanal and say they didn’t know there were risks. The guidance was there, the instructions were clear, and we knew the problem. The question is now whether we will do anything about it.
Geoff Wilkinson is the managing director of Wilkinson Construction Consultants.
This is a shortened version of an article that appeared in The Daily Telegraph