The Grenfell Tower Tragedy

In 1974, a new high-rise public housing apartment building opened in West London.  Called Grenfell Tower, it was 24 stories tall and designed to house as many as 600 people in 120 apartments.  Photographs of it taken before a renovation in 2015 show large windows on one side and smaller ones on the adjacent side. 

In 2014, as reported in this blog, the 63-story Address Hotel in Dubai, United Arab Emirates went up in flames as aluminum-clad foam-plastic panels called architectural cladding or sandwich cladding on its exterior caught fire and quickly spread the conflagration to most of the outside of the building.  Amazingly, no one died in that fire, due to a quick evacuation order by the authorities and the failure of the fire to spread to the interior of the hotel rooms.  But this was only one of numerous exterior-cladding fires that have resulted from the use of flammable architectural materials on buildings that are too tall to be reached conveniently by fire ladders.

In 2015, the Kensington and Chelsea Tenant Management Organization, the bureaucracy in charge of public housing in the Grenfell Tower district, decided to do a renovation, possibly to improve the structure's insulation and lower heating costs.  New windows were installed, thermal insulation was added, and to cover these changes, sandwich cladding panels were installed to cover the four exterior side walls. 

Some, perhaps most, of the cladding was made by the U. S. firm Arconic, which sells various types with different kinds of plastic between the outer aluminum sheets.  A cheaper type uses polyethylene plastic, but is not recommended for structures over 10 meters (33 feet) tall.  A slightly more expensive type is fire-resistant, as was the thermal insulation used underneath the cladding.  But even fire-resistant plastic can burn under some conditions.

When constructed, the building had no sprinkler system, but the apartments were piped for gas cooking and gas lines were present throughout the building.  Each apartment had fire detectors, but a residents' organization called the Grenfell Action Group has voiced complaints to authorities over the past few years about outmoded and non-functional fire extinguishers, flammable clutter in hallways, and other fire-safety issues, with little apparent response.

Residents of the Grenfell Towers, as were most other residents of London, had been instructed in case of fire to remain in place to be rescued by firefighters, rather than attempt an escape on their own.

In retrospect, the Grenfell Towers fire was a disaster waiting to happen:  an aging, open-style building without a sprinkler system but full of gas lines, covered with apparently flammable sandwich cladding outside potentially flammable insulation material, crowded with up to 600 residents who had been told to stay in their apartments in case of a fire.  And in the early morning hours of June 14, 2017, a fire broke out, reportedly in a kitchen on the fourth floor.

No sprinkler system or fire extinguisher succeeded in stopping the blaze before it ignited the exterior cladding, which in a matter of a few minutes spread the flames upward and eventually completely around the structure.  Many survivors got out by disobeying the orders to stay in place.  As of this writing (June 18), the estimated death toll is 58, and is expected to go higher.  If this is confirmed, it will be the largest number of people to die in a single fire in London since the Blitz of World War II.

Fires that kill lots of people at once are not that uncommon, but usually they happen in crowded single-room venues such as nightclubs where fireworks or other sources of ignition catch flammable materials on fire.  The spectacle of an entire high-rise building going up in flames because of flammable exterior cladding is something that is not supposed to happen in modern "fireproof" structures.  But the invention of a cladding material that is light, inexpensive compared to concrete, solid steel, or aluminum, and reasonably durable has led to its use and abuse throughout the world.  And as numerous cladding fires have shown, you can take the most fireproof building in the world and surround it with thin, flammable sheets exposed to a lot of air, and what you get is a giant Roman candle waiting to be set off. 

The Grenfell Towers fire may become a turning point in the politics and regulations of exterior cladding, similar to the infamous Triangle Shirtwaist Factory fire in New York City that killed 146 garment workers in 1911.  Like many of the residents of the public-housing Grenfell Towers, most of those who died in the 1911 fire were poor immigrants, though they died on the job amid flammable clothing materials, not at home surrounded by flammable architectural panels.  The Triangle fire had the good result of inspiring calls for improved fire-safety building codes and regulations, which if implemented can prevent tragedies like this.

British Prime Minister Theresa May, already in a politically weak position, has been jeered and attacked for what many saw as her inadequate response to the tragedy.  She and other politicians could turn this situation to the benefit of their country by leading a thorough investigation into the causes of both the Grenfell Towers fire and other similar fires in which flammable exterior cladding has played a role.  Then, they could take vigorous and definite action with regard to both existing and future architectural cladding that has any significant chance of short-circuiting fire safety by enabling the spread of a fire on an otherwise fireproof structure's exterior. 

It is ironic that after making people suffer for centuries the hazards of living in wooden structures that were chronically prone to burn down, nineteenth-century architects thought they had solved the problem of fire with concrete-and-steel structures, only to torch their triumphs in the last few decades by using what amounts to cheap window-dressing materials that burn like fireworks.  If I were an architect, I would be afraid to show my face in London after the Grenfell Towers tragedy. 

The most basic ethical requirement of a profession is that the professionals look out for the interests of those average citizens affected by their professional activities, citizens who have no way of knowing what hazards they could be subject to and how to avoid them.  I would be surprised if more than a few residents of Grenfell Towers knew anything about sandwich cladding, or the fact that under the right circumstances it would burn.  Well, everyone knows now.  And I can only hope that this knowledge gets applied to similar dangerous situations, and we do whatever it takes to keep another Grenfell Towers fire from happening anywhere, ever again.

Sources:  I referred to news reports about the Grenfell Towers fire carried by the Australian Broadcasting Company on June 17 at http://www.abc.net.au/news/2017-06-17/grenfell-tower-panels-not-suitable-for-tall-buildings/8627790, the Canadian Global News at http://globalnews.ca/news/3536188/grenfell-tower-fire-death-toll/, and the Wikipedia articles "Grenfell Tower fire" and "Triangle Shirtwaist Factory fire."  My blog on the Address Hotel fire in Dubai appeared on Jan. 4, 2016.

Sandwich Panels and the Dubai Hotel Fire

If you were watching TV on New Year's Eve, amid all the spectacular fireworks displays in cities around the world you might have also seen an unplanned spectacle:  the blaze climbing up one side of the 63-story Address Hotel in Dubai, the largest city of the United Arab Emirates (UAE).  While the Address Hotel is not the tallest skyscraper in the world (that honor goes to the Burj Khalifa, also in Dubai), it's tall enough to attract global attention as it was enveloped in flames during the night.  Amazingly, no fatalities were reported, although numerous people suffered smoke inhalation or minor injuries while the hotel was being evacuated.  The main reason for the absence of serious casualties was that the fire was confined almost entirely to the "sandwich panels" or cladding on the outside of the building.  Why they could catch fire—and why entire buildings are covered with flammable material in the first place—are topics worth pursuing.

As most people know, modern skyscrapers depend on a hidden steel skeleton for mechanical strength, not on the exterior surfaces, which can be chosen for properties other than their ability to support the building.  At first, high-rise architects stuck to the traditional stone, concrete, and brick for facades, but in the 1950s, they began to experiment with lighter-weight and cheaper materials, such as glass and aluminum. Properly handled and mounted, aluminum makes a fine, long-lasting sheathing material, and so does glass.  Then a couple of decades ago, someone had the idea of sandwiching a few millimeters of plastic—polyethylene or some other heat-softening—between two thin  foil-like claddings of aluminum, making something cheaper and lighter but just as good-looking as solid aluminum.  Thus the sandwich panel was born.

Now, most heat-softening (thermoplastic) plastics can burn very easily, and some attempts were made to introduce fire-retardant materials into the plastic core of sandwich panels to make them fire-resistant.  Apparently, these attempts did not convince U. S. building-code authorities that the new sandwich panels were safe enough to use in high-rises.  A comment on an architect's chatroom I found indicates that these types of panels are prohibited in the U. S. for use on buildings taller than about four stories.  But other countries either had no such laws, or came to realize the potential for disaster too late.

What can happen is this.  If you have a whole building encased in this stuff, and one panel near the bottom happens to catch fire somehow (fireworks seem to be a popular way to do this), you are in big trouble.  Aluminum has a low melting point and melts away from the plastic cladding as soon as the flame reaches it, exposing more plastic to air and letting the fire feed on itself.  Hot air and flames travel upward to the next panel and so on, and in the case of a 63-story building, there's plenty of upward to travel through.  This is what happened, apparently, not only to the Address Hotel, but to several other similarly-clad high-rises in Dubai and elsewhere in the last few years.  The architect-chatroom website where this problem was discussed has numerous pictures of burned-over building exteriors in Dubai, China, and elsewhere—all fires in which sandwich panels played a critical role.

Fortunately, the fires that these panels support tend to stick to the outside, and most of the time, people inside the buildings have time to evacuate before anyone gets killed.  But nobody wants to leave a building under duress while dodging falling pieces of burning plastic and metal on your way out.  And it's very costly to clean up the resulting mess and re-cover the structure with something that won't burn as easily next time.

Both Australia (where such a fire happened in Melbourne in 2014) and the UAE have changed their building codes to require sandwich panels to pass certain fire-retardant tests.  There are two problems with this, however.  One, it's not clear exactly how fire-retardant a panel has to be in order to resist spreading a fire on a tall building.  The only sure way to know is to build such a building and try to set fire to it, and this experiment is beyond the resources of most building-code-writing organizations.  Second, such codes generally apply only to new construction, and are not retroactive.  So anyone who's already built a skyscraper with flammable cladding doesn't have to take the cladding down and replace it with something better.  That is, until it catches fire.  Judging by the fact that the Address Hotel fire was the third such conflagration in Dubai in three years, it may be only a matter of time until the others light up too.

Modeling how fires start and spread is still an inexact science, and it is understandable that pressures from the building industry allowed dangerous sandwich panels to be installed in many places around the world, despite the hazards involved.  But it takes only one or two fires like this to demonstrate that there's a serious problem.  The almost universal tradition of not making building codes retroactive makes sense, because taking stuff out of an existing building to replace it can be more expensive than the original building cost.  Better in that case simply to condemn the thing and tear it down, but that's an extreme measure too. 

So what's the best that can be done in the present situation?  There may be some lower-cost ways to reduce the chances that a fire in existing sandwich panels will spread, possibly by installing some kind of fire-break strip at selected heights.  But that would be pretty speculative and might not work.  Another proposal has been to install fire sprinklers on balconies near sandwich panels, because many of the buildings are high-rise apartments, and I bet there has been more than one numskull who's tried to light a barbecue grill on his balcony and let the fire get out of hand.  If a building has potentially flammable sandwich panels, the owners better make sure that all the fire alarms and protection systems are operational, and conducting regular fire drills might not be a bad idea either.  But owners will be reluctant to advertise the fact that their building is a giant firework waiting for someone to light the fuse.

We can also be thankful that U. S. building codes flat-out prohibit the use of sandwich panels in high-rise structures.  Yes, it forces builders to use more expensive materials, and drives the cost up compared to construction costs in other countries.  But we've had enough towering infernos in this country to last us a long time, and we don't need any more.

Sources:  I referred to a Reuters report by Andrew Torchia carried on Jan. 2, 2016 on the Yahoo News website http://news.yahoo.com/dubai-blaze-raises-questions-over-gulf-skyscraper-design-160747983--finance.html#.  The architect's chatroom with a comment about the U. S. prohibition of sandwich panels and photos of similar fires in other countries is at http://www.skyscrapercity.com/showthread.php?t=1801571.  A report of a sandwich-panel-fueled fire in a Melbourne building in 2014 appeared on the Australian website http://www.architectureanddesign.com.au/news/non-compliant-cladding-fuelled-melbourne-apartment on Apr. 28, 2015.  I also referred to the Wikipedia article on sandwich panels.