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  • International Workplace
  • 19 June 2017
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Grenfell Tower: a personal perspective

With a picture beginning to emerge of the contributory factors that may have led to the fatal fire at Grenfell Tower last week, as a health and safety professional it’s hard not to have a personal perspective.

Harriet Harman MP made a most telling contribution by pointing out that residential tower blocks, unlike commercial ones, might not have sprinklers and often only a single escape stair. I’m not able to check the fire safety strategy for 4,000 residential blocks of flats in the UK, but from experience that seems to be largely true.

Commercial blocks are different. Even an older building, such as 20 Fenchurch Street (now demolished), where I was safety officer for an investment bank in the early nineties, had two separate flights of escape stairs on opposite sides of the central core. It also had wet risers (fire-fighting pipework within the building permanently charged with water and ready to use). There were sprinklers in common parts such as the basement and car park and floor landings.

There was a staged fire alarm system, tested every week, that evacuated the fire floor, the one above and the one below immediately and then evacuated other floors in a cascade. The building was immediately accessible for the brigade and fitted with smoke ventilation that allowed fire fighters to clear smoke so they could work. The building air ventilation was damped and all penetrations were to be fire stopped (although we always found a few holes that were missed in inspections). All of the above came about because the building was ‘Section 20’.

What that meant was that a specific set of additional fire safety requirements pertained to large buildings under Section 20 of the London Buildings Act[1] 1930 as amended. It applied only to inner London buildings over 30m in height (or a significant horizontal capacity) and was only repealed in 2013.

Only recently I learned about the different strategy for residential tower blocks. I was looking over some fire safety advice a colleague was giving about ‘Stay Put’. Being from a commercial background this whole policy was news to me. But is seems that a strategy of full and complete evacuation of tall buildings in a fire following detection was by no means universal. Residential blocks were in use that only had a single means of escape.

The principle of ‘containment’ as it is called is that fire should not be able to spread from a single unit. For this to work the unit must be mostly constructed of very fire- and smoke-resistant material (which concrete usually is) and that containment must remain effective for at least an hour. All such containment is only as good as the weakest link. The older your building is, the more likely there are to be penetrations through fire barriers, perhaps to run cables and pipes, where flame and smoke can progress. The doors to a unit will also be a weak point so the corridor needs to be inert; not only to prevent fire spread but also to keep options to escape open for neighbours. And, of course, windows will be another weak point.

Evidence on fire spread at Lakanal House (in which six people died in July 2009), from a point of origin on the ninth floor indicated:

Although neighbouring floors appear unaffected, smoke is soon seen at this fifth floor window. Architect Sam Webb – an expert in assessing the risks of post-War social housing – speculates that molten material fell from flats above and spread the fire, probably by igniting curtains.

Evidence has been forthcoming since then that flame at the exterior, as well as interior penetrations breached the containment and contributed to fire spread in Lakanal. It was also noted at that enquiry how many of those buildings had no or inadequate fire risk assessments.

One would like to think that after an enquiry of that prominence, we would have seen significant changes to fire safety arrangements for such properties going forward. However, we are still looking at an Approved Document B that is not current with some building construction and refurbishment practice. For example, building alterations are becoming necessary to ensure building envelopes are insulated to meet energy efficiency standards.

This can be achieved by cladding either interior or exterior surfaces. Understandably, interior insulation is not desirable because it would reduce the available square footage and require new decoration. Building exteriors, however, can support additional insulation, assuming it is weatherproof, lightweight (not to add a significant structural load) and will not interact with or corrode the underlying structure which may already be quite old. The use of aluminium façade panels backed with insulation also makes the building look smart and modern. Though it should obviously also be constructed so as not to exacerbate the spread of fire.

As windows are often a source of heat loss, they are often also replaced with better glazing during such façade works. Both the façade and window construction, which could have acted as a conduit to breach containment, will be an important area of focus in investigation. Breaches of fire stopping within the building where legitimate penetrations for power, data, gas and water take place, through internal walls or concrete floors and ceilings, will also need to be examined.

The exterior façade material appears now almost completely burnt away. A very important question for an enquiry to establish is whether or not that occurred as a result of a fire that was already far more intense than containment should normally allow or whether, in fact, the exterior was the catalyst for unprecedented fire spread. On behavioural safety, it is really important that we establish, as soon as we can, whether or not the containment and ‘stay put’ philosophy is a valid policy or if it hasn’t been fatally undermined. Lastly, the absence of sufficient means of escape and the contribution of sprinklers to limiting fire spread in a fire of this type should be spelled out. A potentially enormous change to fire engineering design and fire safety practice will hang on this enquiry.

Things must change. Along with the incredible efforts of the emergency services, we professionals working in fire safety, engineering, construction management, risk assessment and safety training need to do our part to support the victims of this disaster in every way we can.

We can play a substantial role in ensuring that the work we do is of the highest professional standards. We can lobby for change, make our voice heard and contribute to consultation on how best to make sure this never happens again. We can make sure that when we see something of concern, we put our case to our clients for improvements in the most assertive and effective possible way to ensure we are heard and advice is weighted with a precautionary bias; with a risk averse bias commensurate with the inescapable knowledge that fire doesn’t ever really ‘behave’.

Fire is an incredibly unpredictable hazard about which we, sadly, continue to have to learn new and horrible truths. We need to make sure that everyone in our organisation is under no illusion about how dangerous a fire is – in any building, but especially one in which people sleep – and under no misapprehension of what they must do if a fire starts.

[1] Specifically The London Building Acts (Amendment) Act 1939 only applies to Inner London and is incorporated in the Building (Inner London) Regulations 1985.

 

Stacey Collins

Head of Environment, Health and Safety for International Workplace