Phase 1 Inquiry Report - https://www.grenfelltowerinquiry.org.uk/phase-1-report
Hi and welcome, to Failurology; a podcast about engineering failures. I’m your host, Nicole, and I’m from Calgary, Alberta.
I have over a decade of experience in the field of mechanical engineering in building science; directing the construction of plumbing, heating, ventilation, and air conditioning systems in various high rise, multifamily residential and commercial buildings across western Canada. I love reading about engineering failure case studies. Not just the science behind what went wrong, but what we can learn as an engineering community to prevent future failures from happening.
Starting a podcast has been a dream of mine for a long time. And it’s been a bit of a learning curve. I want to thank each and every one of you for listening. I hope these stories interest you as much as they interest me. Check out the link in the show notes of this episode to see photos from this week. And please rate, review and subscribe to the podcast so more people can find it.
News – Concrete Recycling
This week in engineering news; a five year study shows that recycled concrete performs as well, or in some cases better, than conventional concrete.
Researchers at the University of British Columbia’s Okanagan campus School of Engineering in Kelowna British Columbia compared recycled and conventional concrete on a municipal sidewalk and a building foundation over a five year period. They found that after five years of service, the recycled concrete had comparable strength and durability to the traditional concrete.
Concrete is typically made from a mix of 10-15 percent cement, 60-75 percent aggregate and 15-20 percent water. The recycled concrete replaces the aggregate used in traditional concrete making.
Researchers found that the recycled concrete adequately compared to the traditional stuff, and was even stronger after the initial 28 day cure.
Waste materials from construction and demolition make up about 40% of the worlds waste.
Shahria (sha-ha-ria) Alam, co-director of UBC's Green Construction Research and Training Centre and the lead investigator of the study states"A number of countries around the world have already standardized the use of recycled concrete in structural applications, and we hope our findings will help Canada follow suit."
Check out the link in the show notes if you want to read more on the study.
Now on to this week’s engineering failure; the Grenfell Tower Fire in London England.
When the Grenfell Tower caught fire in June 2017, it made the news over here in Canada. I have been loosely following the story ever since, but it wasn’t until I dug into the details while researching this episode that I realized there was a much, much larger conversation to be had about the combustibility of building materials. To be honest I’m still a little in shock about how this could have happened, and that the Grenfell fire isn’t the first time. But I’m getting a bit ahead of myself, let’s start at the beginning.
Grenfell Tower was a 24 storey, 67m tall ,residential tower, referred to as a tower block, located in North Kensington, West London, in the United Kingdom.
The tower was part of a larger complex. There were three low rise “finger blocks” connected to Grenfell – Barandon Walk, Testerton Walk and Hurstway Walk.
Constructed started in 1972 and finished in 1974. The tower was designed in the brutalist style, which is a minimalist architectural style showcasing the construction building materials over decorative design. Brutalist buildings look very utilitarian and kind of cold. We have a few in Calgary. And honestly, it’s not my favorite style.
The original Grenfell Tower architect was Clifford Wearden and Associates and it was built by A E Symes (S-eye-ms)
The tower consisted of 120 one and two bedroom flats, with 6 dwellings per floor, to house approximately 600 people. None of suite partition walls were structural, since it was designed to be flexible so that floor plans could be easily modified to accommodate more or less suites.
Grenfell tower was part of a public housing complex, referred to in the UK as council housing, owned by the Kensington and Chelsea London Borough Council, and managed by the KCTMO (Kensington and Chelsea Tenant Management Organization) which is made up of four council-appointed members and three independent members
At the time of the fire, fourteen of the flats had been bought under a “right to buy” policy and were occupied by either leaseholders or rented out on the open market, but the rest were subsidized.
Grenfell tower housed poorer, mainly ethnic minority, residents in one of the wealthiest locations in the country. This is important, we’re going to circle back to it later.
A major renovation of the tower was announced in 2012 and took place in 2015-2016 with the objective of replacing the substandard heating system, replacing the windows, increasing thermal efficiency of the tower, and improving the appearance.
There were several players in this major renovation, but the key ones are as follows.
Architect – Studio E Architects
General Contractor – Rydon Construction who carried Harley Facades to replace the building exterior, which I will be referring to as the building envelope. The renovation work had been originally contracted to Leadbitter, for 11.278 million pounds, but was instead given to Rydon for 8.7 million pounds
Contract administration – Artelia
Specialist mech and elec consultants - Max Fordham
Main Contractor – WITT UK, Harley Facades, Celotex, JS Wright & Sons, Arconic
The renovation project included upgrades to the existing envelope, which would accomplish two of the main objectives; increase thermal performance and improve the appearance. The building was re-clad with a 150mm external insulation and aluminum composite cladding.
Before the fire, a group of residents banded together to form the Grenfell Action Group (GAG).
Between 2013 and 2017 they published 10 warnings criticizing fire safety and maintenance practices within the tower block.
Calling out flaws with the towers emergency lighting system in 2005
In 2013 they published a fire risk assessment done by a tenant management organization; which outlined the following concerns.
Firefighting equipment at the tower hadn’t been checked for up to 4 years
Fire extinguishers had expired.
Some extinguishers had “condemned” written on them
The Grenfell Action Group also documented numerous attempts to contact the Kensington and Chelsea Tenant Management Organization and the council Cabinet Member for Housing and Property but never received a reply
In July 2013 –the Kensington and Chelsea London Borough Council threatened legal action against the resident group for alleged “defamatory behavior” and “harassment”.
In Jan 2016 – The Grenfell Action Group warned that people might be trapped inside during a fire, as there was only one entrance and exit for the tower and corridors were allowed to be filled with garbage such as old mattresses
The group stating - "[We] predict that it won't be long before the words of this blog come back to haunt the Kensington and Chelsea Tenant Management Organization and we will do everything in our power to ensure that those in authority know how long and how appallingly our landlord has ignored their responsibility to ensure the health and safety of their tenants and leaseholders. They can't say that they haven't been warned!"
The group also warned about exposed gas pipes in months before fire. In 1968 exposed gas pipes exploded in at Ronan Point a 23 storey council tower in east London, collapsing an entire corner of the building.
The tower did not have fire sprinklers, similar to the majority of tower blocks in the UK
In June 2016 – independent assessor found 40 serious issues with fire safety – requiring within weeks
In Oct 2016 no action had been taken
In Nov 2016 the London Fire and Emergency Planning Authority served a fire deficiency notice, listing many fire safety issues at the tower – requiring action by May 2017 – including fire doors, smoke venting system, and firefighters’ lift controls
As you can see, multiple groups flagging multiple safety issues to the council before the fire, but nothing was done.
On June 14, 2017 – 50 minutes after midnight local time a fire started from a malfunctioning fridge-freezer on the fourth floor in flat 16 and burned for roughly 60 hours before being extinguished. I want to take a second to mention that the 4th floor was not the fourth floor from grade, it was actually the eighth. Floors from bottom up went ground, mezzanine, walkway, office, 1st, 2nd, 3rd, 4th and so on. From what I’ve read, this seems to be common in the UK.
A call to 9-9-9 (or 9-1-1 in North America) went out 00:54 (or 12:54am),
By 1:09 the fire began to penetrate the window frame
Firefighters entered the fourth floor flat around 1:14am
At 1:13 - more pumps and an aerial appliance were requested – the water jet on scene couldn’t reach higher than 4th floor, which remember is really the 8th floor above the ground.
By 1:15 – smoke had spread to flat 26 which is the flat above where the fire started.
By 1:18 – 34 of 293 residents escaped – another 76 escaped by 1:38 – woken up by smoke alarms when smoke entered their flat – I read that the fire occurred during Ramadan, and many Muslim residents were awake and able to alert neighbors.
I’m going to pause the timeline here to point out a few things. First, the building didn’t have a central fire alarm; aside from someone going door to door to notify people, the only way residents were aware of the fire was when smoke entered their suite and set off the individual smoke alarms. And second, the buildings emergency policy was to shelter in place. That meant that the residents were expected and told to stay in their suites until the fire could be extinguished; which is apparently standard policy in the UK. There were a couple reasons for this, one is that there was only one stairwell to exit, and it was thought it would become too crowded, and since the building was concrete and each unit was fireproofed from the others, it was believed that a fire would be contained and extinguished before it could spread. None of these things make sense to me; you’re just asking for trouble here. I can’t somewhat understand that a central fire alarm system was not part of the building code in 1972, although a publicly owned building should have been upgraded at some point. But the shelter in place policy is the really crazy part. I can think of no scenario where sheltering in place would be my plan A. Maybe if exiting was unsafe, but to just sit tight 20 floors in the air and hope for the best without trying anything else. No, absolutely not. No thank you. Couches and curtains are extremely flammable.
By 1:27 fire had reached the roof at a “terrifying rate”
The fire doors throughout the building didn’t close or seal properly and smoke began to spread from the affected flats into the lobbies
Between 1:30-1:40am smoke entered the stairwell – although it was still passable for another 30 minutes
At 1:42 fire had spread to the north side of the tower after starting on the east side
Between 1:38 – 1:58 another 20 people escaped, and another 48 people would escape by 3:48
At 2:47 – shelter in place order was officially lifted – Later investigators would determine the order was lifted 80 minutes later than it should have been.
By 4:44 all sides of the building were affected and people, if they could be reached at all, were told to self-evacuate.
last resident was rescued at 8:07am
The rescue teams were able to evacuate all residents up to 10th floor – all but two up to the 12th floor – but only two people from the highest two floors.
72 people died, 70 were injured and 223 escaped. All of it was preventable.
The Grenfell Tower fire is the deadliest structural fire in the UK since 1988 when the oil platform Piper Alpha explosion killed 167 people.
It is the worst UK residential fire since World War II.
More than 250 firefighters, 70 fire engines, 100 ambulance crew and 20 ambulances attended the scene
Fire affected the three low rise “finger blocks” connected to Grenfell which were evacuated for fear of tower collapse. The low rise buildings also lost hot water as they shared boiler with the tower.
The following afternoon the building was assessed and determined to not be in danger of collapse
There were also several issues encountered by the London Fire Brigade (LFB) while fighting the fire.
Water pressure was inadequate
High ladder arrived after 32 minutes, at which point the fire was out of control – policy has since been updated to send a high ladder to tower fires
Radio communication didn’t work – either due to overuse and interference with the concrete strucutre
Aerial appliances, due to narrow London streets, could only reach 32m – a 42m platform was borrowed from Surrey but after the fire had been burning for several hours
Single stairwell restricted access – filled with smoke an hour after the fire started
To this day, the UK only requires one stairwell in towers
In North America, and probably other jurisdictions that I can’t speak for, every interior space must have two points of exit. And in Calgary, as well as some other jurisdictions, a mechanical ventilation system is used to pressurize the stairwell and prevent smoke from entering.
Vast majority of UK tower blocks don’t have sprinklers –only 2% of UKs council and housing association owned tower blocks have sprinklers – even though there is an 87% reduction in deaths when sprinklers are installed – sprinklers have been required since 2007 in new buildings but there is no requirement to retrofit. In Calgary, I’ve worked on some projects where the building owner receives government grants to retrofit sprinklers into an existing building during a major renovation. But I don’t know if this program exists in the UK.
It was determined that the fire spread rapidly up building exterior envelope due to the cladding, external insulation and air gap between them which enabled stack effect.
You may have noticed that I’ve been referring to Grenfell in the past tense. That’s how bad this fire was. While the building did not fall down, it’s expected to be deconstructed by 2022. Its currently covered in a protective wrap for forensic and aesthetic purposes. This is probably a good thing, so no one has to look at it anymore.
So what went wrong? Why did the fire spread so fast?
The building envelope upgrades included insulation, an air gap and then the exterior cladding.
Both the cladding and insulation used were combustible and not recommended, by their own manufacturers, for use on a building this size. The manufacturer is based in the US, where this product is not permitted on high rise structures, as it does not pass National Fire Protection Association or NFPA section 285 testing. But the UK doesn’t require contractors and developers to follow NFPA, as it’s a US code. There is a similar UK code, the British Standard 8414, but even that doesn’t seem to be adequately enforced. Even though there had been similar fires before Grenfell, the problems with the cladding and insulation seemed to have been overlooked.
The cladding used at Grenfell was the Reynobond PE model manufactured by Arconic. It is made from two coil coated 3mm aluminum sandwich plates, fusion bonded to both sides of a polyethylene core. The core is the main issue with this product, as its combustible.
according to Arconic’s own brochure – the polyethylene core cladding is only permitted on buildings up to 10metres tall or about 3 stories – they also have a fire resistant core cladding, but that product is only permitted up to 30 metres or about 9 stories – above that the non combustible A2 cladding should to be used
The cladding installation was passed on May 15, 2015 despite warnings that combustible insulation should only be used with cladding that doesn’t burn
Several groups, including the manufacturer said that the cladding shouldn’t have been used on a building of this height, yet it was passed by all stages during construction
In North America, under NFPA 285 – a mock up of the entire planned assembly is constructed two storeys tall with a window in the middle – It is then ignited with gas from two different angles for 30 minutes – flames cannot spread more than 3m vertically and 1.5m horizontally from the window for the assembly to pass the test.
PSA – The National Fire Protection Association or NFPA code is accessible for free on the internet. You just have to create an account. I use it regularly to look at sprinkler requirements under section 13 as well as commercial kitchen exhaust under section 96. NFPA 285, which is the Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Wall Assemblies Containing Combustible Components is only 35 pages. Yes the title is long, but the chapter itself is short, and it describes the entire set up and procedure of the test pretty clearly
Test can cost 30k and any changes to the assembly means a new test
I have yet to find an ACM or aluminum composite material cladding with a polyethylene core that has been able to pass the NFPA 285 test.
Based on the sample of information I have from researching the Grenfell fire, in my opinion, the UK governments mandate and testing are insufficient and lack transparency –which I find ironic considering the standard shelter in place order that existed at Grenfell
Mark Harris – Harley Facades – “from a selfish point of view” his company’s preference was to use a (cheaper) aluminum composite material - Install by Harley Facades of Crowborough East Sussex was 2.6 million pounds. Alternative cladding with better fire resistance was refused due to cost
The cladding itself wasn’t the only thing that caused the fire to spread so fast.
There was a standard ventilation gap (50 mm) between the cladding and the insulation behind it
cavity barriers intended to prevent fire spread in this gap were too small or incorrectly installed. This allowed the fire to spread through the gap quickly. The gap also created a stack effect issue. As the hot smoke rose through the cavity and out the top, it created a vacuum of sorts, drawing in cooler fresh air at the bottom. The fresh air not only helps to feed the fire, but the hot smoke traveling up the cavity also helps to spread the fire.
The insulation itself was also a problem. There were two types on insulation used at Grenfell; Celotex and Kooltherm.
One more thing – the new double-glazed windows of unknown type and material, mounted in the same vertical plane as the PIR foam insulation plates, were less fire resistant than the ones they replaced and too small; contributing to spread between interior and exterior
To recap, the cladding was combustible and not recommended on a building over 10m tall. The insulation was not recommended to be used with combustible cladding. The air gap between the cladding and insulation did not contain the necessary cavity barriers and not only allowed the fire to spread, but actually helped it. And lastly the windows contributed to the fire and smoke spread from the building envelope into the suites.
Despite all of these things, council building inspectors visited the site 16 times from Aug 2014 to July 2016 and passed the building.
The fact that the fire ever happened is already so terrible, but what’s happened since and what’s been uncovered is almost as bad.
Theresa May, UK Prime Minister at the time, visited the site the day after the fire and visited survivors the day after that. She has been widely criticized for her reaction.
Following the fire, there have been several resignations
Conservative council leader Nicholas Paget-Brown resigned on June 30, 2017
LFB Commissioning Dany Cotton retired early in Dec 2019 following criticism of the response
the council deputy leader and chief executive also resigned
Council had 274 million pounds in reserves in 2017 after years of under spending – despite this some residents still had rent payments deducted from their accounts after the fire
The building was insured by Protector Forsikring ASA for 20 million pounds – not enough to cover the direct costs; which are expected to be 1 billion pounds when factoring in litigation, compensation for death/injury, rehousing and rehabilitation, demo and rebuilding, as well as improving/evacuating other tower blocks
There are estimates of at least 600 other private and council UK tower blocks that have a similar cladding assembly
The intent is to start replacing cladding in the buildings of the concern
But the replacement cladding has also failed tests – each individual component was of “limited combustibility” and it was assumed, incorrectly, that the assembly would be ok. But it failed the fire tests. At least they are testing it though.
Tower blocks that haven’t had the combustible cladding replaced yet are supposed to have alarm systems and patrols in place to evacuate
In Aug 2017 – a 52 bed trauma unit at John Radcliffe hospital in Oxford closed for 12 months due to the cladding material they used on that building
In Nov 2017 – Kensington Conservative Party sent survey to local residents to rate importance of the fire alongside parking and recycling issues – which is quite tone deaf
In Oct 2018 – the UK government planned to ban flammable cladding on new buildings over the specified height – The manufacturer literature already says it’s not permitted, I’m not sure a formal ban is required. But, enforcement of the necessary test requirements by the UK government would be definitely be beneficial.
On May 9, 2019 – Housing Secretary James Brokenshire allocated 200 million pounds to replace cladding on private tower blocks
A fire safety bill, which included provisions for building owners and residents to share information with fire department related to design and materials used in exterior walls, as well as requirements for regular inspections and sharing of evacuation procedures – was defeated 318 to 188 on sept 7, 2020 – I don’t know what else was in the bill or why it didn’t pass, but the government promised the people that they would implement recommendations from the phase 1 inquiry into the fire and so far they have failed on that promise.
The building has been covered with a scaffolding, protective wrap, and an exterior elevator which we call a skip hoist. It is expected to be demolished in 2022.
Government set up a fund to support survivors – But I’m sure its not enough
Systemic failure of the current building regulation system – calls on government to cover costs
The fire is also considered by some to be Social murder when political decisions led to the preventable death of poor and under privileged people. I briefly touched on environmental racism in episode two regarding the handling of the New Orleans evacuation and rescue operations during Hurricane Katrina. But I want to expand a bit on that more now. Environmental racism refers to the disproportionate exposure to hazards that lead to a negative impact on quality of life. These hazards can be environmental pollution, lack of access to clean drinking water, proximity to toxic waste sites, or in this case, a lack of fire safety upgrades, lack of maintenance of existing life safety systems and general failure to address the very real concerns of the residents with respect their safety.
When I said the Grenfell fire started a much bigger and long overdue conversation, I wasn’t kidding. Grenfell was preventable and it’s definitely not ok that anyone died. The small silver lining here is that the fire uncovered a bigger problem, and the exposure it’s gotten could help prevent more deaths.
Check out the podcast page, link in show notes, for photos from this week’s episode. And if you want to chat with me, my twitter handle is @failurology. Thanks everyone for listening. If you’re enjoying what you’re hearing; please rate, review and subscribe to the podcast so more people can find it. And don’t forget to tune in next week to hear about the Ford Pinto; the car that was known for exploding when rear ended. Yes, you heard that right, the Pinto exploded when rear ended. But more on that next week. Bye everyone, talk soon.