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Grenfell Inquiry: ACM cladding was ‘primary cause of fire spread’ and tower did not comply with regulations, judge rules

The judge leading the Grenfell Tower Inquiry has ruled that the cladding installed on the tower did not comply with building regulations, finding that the polyethylene-cored panels were the “primary cause” of the rapid spread of flames.

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Sir Martin Moore-Bick, chair of the Grenfell Inquiry (picture: Grenfell Tower Inquiry)
Sir Martin Moore-Bick, chair of the Grenfell Inquiry (picture: Grenfell Tower Inquiry)

Judge of the Grenfell Tower Inquiry rules that the ACM cladding made the tower non-compliant with regulations and was the “primary cause” of the fire spreading up the block #ukhousing

Sir Martin Moore-Bick published his long-awaited report today, setting out a number of ways in which building failures contributed to the spread of the fire that killed 72 people in June 2017.

The 865-page report, which was also deeply critical of the London Fire Brigade, found:

  • Changes to the walls of the tower made during the refurbishment meant it was in breach of Regulation B(4), which requires the external walls of a building to “adequately resist the spread of flame”
  • The aluminium composite material (ACM) cladding panels was the “primary cause” of fire spread up the tower, adding that it was “more likely than not” that the plastic insulation also contributed

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  • An ‘architectural crown’, also made of ACM, at the top of the tower was the cause of the most rapid horizontal fire spread
  • Flaws in the design of the kitchen window in Flat 16 allowed an “ordinary” and “perfectly foreseeable” kitchen fire to escape the room and ignite the cladding
  • The building suffered a “total failure of compartmentation”, with missing self-closers on fire doors a crucial contributing factor

Survivors of the fire had called on Sir Martin to make a clear statement that the building did not comply with regulations – hoping it would mark the first step on a journey towards accountability for the errors.

British building regulations are expressed in high-level ‘performance-based’ standards, with more detailed and non-compulsory guidance contained in ‘approved documents’ published by the government.

Sir Martin opted to make an early finding that the building breached the headline regulation, although he has not yet made any statements on its compliance with the approved documents.

He said: “Although it was not originally my intention to reach conclusions… about the tower’s compliance with building regulations, I can see no good reason why that question should not be determined now so far as it relates to the external façade.

“There is compelling evidence that Requirement B4(1) was not met in this case. It would be an affront to common sense to hold otherwise.”

The polyethylene inside the ACM panels was cited as the “primary cause” of the spread of fire up the cladding, with Sir Martin citing evidence that the plastic has “a heat of combustion similar to that of petrol or diesel fuel”.

He rejected submissions from cladding manufacturer Arconic, insulation manufacturer Celotex, and contractor Rydon that there was insufficient evidence to draw conclusions about the causes of the fire spread.

“I am satisfied that, although many different factors played a part, the principal reason why the flames spread so rapidly up the building was the presence of the ACM panels with polyethylene cores, which… melted and acted as a source of fuel for the growing fire,” Sir Martin said.

He added that it was “more likely than not” that Celotex’s polyisocyanurate insulation boards and Kingspan’s phenolic panels “contributed to the rate and extent of vertical fire spread”, although he said it was not yet possible to quantify exact contributions.

He also noted evidence that the spread of flame upwards at Grenfell Tower was actually one of the slowest compared with other ACM cladding fires that have happened overseas in recent years – with flames spreading at Grenfell at a rate of four metres a minute, compared with a fire in Dubai when the rate was 22 metres.

A diagram of how the fire affected the cladding (picture: Grenfell Tower Inquiry)
A diagram of how the fire affected the cladding (picture: Grenfell Tower Inquiry)

Crucially, though, almost all of these fires burned out when they reached the roof, rather than spreading horizontally and downwards to engulf the whole building as at Grenfell Tower.

“The rapid horizontal and downwards spread of flame was a unique feature of this particular fire, which sets it apart from other international fires and is an important factor in making the outcome so devastating in terms of the loss of human life,” he said.

He said there was “compelling evidence, which I accept”, that the most rapid horizontal fire spread was due to an ‘architectural crown’ – an aesthetic flourish at the top of the building that was also made of ACM.

Sir Martin concluded the horizontal spread was also caused by polyethylene melting and dripping down the building, and the “principal route” of the downward spread was over the columns.

He said it was “unlikely” that defects in the installation of cavity barriers were significant and said there are “fundamental problems” with using cavity barriers which expand during a fire in a cladding system of this type.

While he did not address issues concerning alleged weaknesses in the government guidance and industry practice with relation to the use of cladding, he signalled this would form a significant part of phase two of the inquiry, which commences in January.

He said the inquiry would examine “what was and should have been known both by those in the construction industry and by those in central government responsible for setting fire safety standards”.

There was also serious criticism of the design of the windows for allowing the fire to break out of the kitchen where it started.

inquiry building regs add

One of the fire damaged windows from inside Grenfell Tower (picture: Grenfell Tower Inquiry)

He concluded that the “configuration and materials of the windows and the exterior cladding” gave a “disproportionately high” chance of the fire spreading into the windows.

In fact, he quoted one expert saying it was “almost certain if not inevitable” that a fire of this magnitude would occur in a kitchen at some point, adding that it was “perfectly foreseeable”.

The judge concluded that the most likely means of spread out of the window was due to the new jambs which had been fixed with adhesive to the original pre-refurbishment timber frames.

He said this would have led to the jamb near the fridge freezer deforming as smoke from the fire impinged, carrying with it an insulation board which it was attached to with the adhesive.

This would have allowed the fire to gain access to the cavity between the ACM and the insulation on the wall outside.

However, he also acknowledged a simulation fire carried out for the Metropolitan Police which concluded that the most likely route was via the extractor fan and the infill panel in which it was mounted.

“What really matters is that the design of the refurbishment, the choice of the materials and the manner of construction allowed an ordinary kitchen fire to escape into the cladding with disastrous consequences,” he said.

In terms of the fire breaking back in through windows to other flats, he accepted the “sad fact” that once the fire was burning on the outside it would have broken back in “by one means or another”, such as by smashing the glass in the frame.

However, he added that it was “striking” that so many residents had seen flames enter via extractor fans.

Regarding fire doors, he noted that it was significant that doors on up to seven floors where the fire first penetrated appeared to have missing self-closers, meaning smoke entered the lobbies of the building rapidly when residents fled.

Other doors which were shut allowed smoke to penetrate, he said. He also noted that firefighting operations occasionally involved propping doors open, which allowed smoke to flow into previously unaffected areas, such as the stairwell.

Overall he said: “The building suffered a total failure of compartmentation. How the building came to be in that state is the most pressing question to be answered in Phase Two.”

The Grenfell Tower Inquiry

The Grenfell Tower Inquiry

Closing statements


Day 85: victims' lawyers attack the fire brigade


Further expert evidence

Including some additional evidence from emergency call handlers, bereaved and relatives


Day 84: further evidence from survivors and relatives

Day 83: swift evacuation of tower possible if residents alerted

Day 82: initial fire was extinguished but then returned to the flat

Day 81: overheating fridge-freezer most likely cause of fire

Day 80: fire doors installed did not match product tested

Day 79: resident advised to stay put despite fire in flat

Day 78: insulation and cladding material below required standard

Day 77: molten plastic spread blaze down tower

Day 76: 'stay put' should be dropped when fire spreads across floors


Other witness evidence

Police, ambulance, gas suppliers, council, TMO and call room operators give evidence


Day 75: call room operators give evidence

Day 74: further evidence from TMO officers

Day 73: TMO boss failed to pass information to firefighters

Day 72: fire finally extinguished when gas switched off

Day 71: further questions over stay put advice

Day 70: the police evidence


The bereaved, survivors and relatives’ evidence


Day 69: video shows smoke billowing through fire door

Day 68: KCTMO removed self closing mechanism and never replaced it

Day 67: gaps in cladding fixed with duct tape

Day 66: 'don't fix broken system with a sticking plaster'

Day 65: survivor dragged disabled man down nine floors to safety

Day 64: KCTMO 'did not replace broken fire door'

Day 63: foam insulation inside cladding 'exposed' says survivor

Day 62: father gives harrowing account of son's death

Day 61: council’s management organisation slammed for faulty electrics

Day 60: stay put advice ‘led to deaths’, residents say

Day 59: residents describe problems with new windows

Day 58: survivor describes how daughter saved his life

Day 57: firefighter evidence ‘a slap in the face’, says survivor

Day 56: relations with contractor were ‘toxic’

Day 55: resident 'never happy' with stay-put advice

Day 54: tenant gives evidence about housing association

Day 53: stay put advice 'felt like trap'

Day 52: resident saved by son's phone call


The firefighters’ evidence


Day 51: firefighter feared encouraging residents to jump

Day 50: the LFB commissioner

Day 49: fire chief reveals frustration over lack of building plans

Day 48: internal fire spread 'bigger story' than cladding

Day 47: fire officer considered evacuating crews over building collapse fears

Day 46: 'we were improvising' senior firefighter admits

Day 45: firefighter urged for abandonment of 'stay put' policy

Day 44: firefighter recalls radio signal difficulties

Day 43: call hander 'uncomfortable' with insisting residents stay put

Day 42: residents only told to leave if they called fire brigade back

Day 41: breathing equipment delay 'hampered rescues on upper floors'

Day 40: chiefs told firefighters to abandon policy

Day 39: firefighters reveal dramatic rescue of children

Day 38: firefighters issue aplogies to families

Day 37: council 'unable to provide tower plans'

Day 36: QC defends inquiry process

Day 35: Javid would welcome interim recommendations

Day 34: water from hose 'too weak' to reach the flames

Day 33: 'oh my god, we've been telling people to stay put'

Day 32: further fire fighter describes lack of equipment and low water pressure

Day 31: 'incredibly difficult' task of recording information outlined

Day 30: struggle to maintain control over rescue operation described

Day 29: fire service 'overwhelmed' by survival guidance calls

Day 28: 'the building beat us'

Day 27: firefighters 'forced to abandon plans to reach roof'

Day 26: poor signage hindered rescue efforts

Day 25: water pressure left firefighting equipment 'like garden hose'

Day 24: decision to abandon 'stay put' explored

Day 23: TV images 'could have assissted' rescue effort

Day 22: description of hectic scenes in the control centre

Day 21: account from the fire service 'nerve centre'

Day 20: firefighter describes 'huge volume' of calls from trapped residents

Day 19: firefighter 'given no training on cladding fires'

Day 18: evacuation would have been 'huge catastrophe'

Day 17: firefighters describe access and lift issues

Day 16: scenes of carnage likened to 9/11

Day 15: firefighters recount trauma of survival guidance calls

Day 14: firefighters describe spread of blaze

Day 13: firefighters recall radio difficulties

Day 12: "it was like a war zone"

Day 11: questions raised over fire fighters' radios

Day 10: watch manager emotional under questioning

Day nine: lead firefighter 'not trained in stay put policy'


The expert reports: authors give evidence to inquiry


Day eight: where the fire started

Day seven: what was in the cladding?

Day six: the cause and spread of the fire

Day five: expert highlights key issues

Day four: firefighters defend response to fire

Day three: council and contractors appear for the first time

Day two: lawyers for the survivors make their case

Day one: expert evidence released on cladding and stay put


The commemoration hearings


30 May: Grenfell Council 'recognised it should not house disabled victim above four storeys'

29 May: Anger on day six of the Grenfell Inquiry

25 May: Grenfell families 'forced to live in chimney with stay put policy'

24 May: Grenfell family complained about father being housed on 17th floor

23 May: Tributes to children on third day of Grenfell hearings

22 May: Emotions run high as Grenfell bereaved shown footage of the tower burning

21 May: Grenfell victims share tributes as inquiry opens


The Grenfell Tower Inquiry recommendations: phase one

The Grenfell Tower Inquiry recommendations: phase one

Picture: Getty


There were no plans to evacuate Grenfell Tower available. Sir Martin Moore-Bick, chair of the Grenfell Inquiry, recommended:

  • The development of national guidelines for carrying out partial or total evacuations of high-rise buildings – including protecting fire access routes and procedures for evacuating people who require assistance
  • Fire services develop policies for partial or total evacuation of high rises
  • Owner and manager be required to draw up and keep under review evacuation plans, with copies provided to local fire and rescue services and placed in an information box on the premises
  • All high-rise buildings be equipped with facilities to enable the sending of an evacuation signal to the whole or a selected part of the building
  • Owners and managers be required by law to prepare personal evacuation plans for residents who may struggle to do so personally, with information about them stored in the premise’s information box
  • All fire services be equipped with smoke hoods to help evacuate residents down smoke-filled stairs

Fire doors

Sir Martin said it is apparent that “ineffective fire doors allowed smoke and toxic gases to spread through the building more quickly than should have been possible”, and that missing self-closers played an important role. He recommended:

  • An urgent inspection of fire doors in all buildings containing separate dwellings, whether or not they are high rises
  • A legal requirement on the owner or manager of these buildings to check doors at least every three months to ensure self-closing devices are working effectively


Noting the recommendation from the coroner investigating the Lakanal House fire that the use of sprinklers be encouraged, Sir Martin said that some of his experts had “urged me to go a step further and to recommend such systems be installed in all existing high-rise buildings”.

He said that sprinklers have “a very effective part to play” in an overall scheme of fire safety, but that he had not yet heard evidence about their use. He said that he could make no recommendations at this stage, but that he would consider the matter in phase two.

Internal signage

Floor numbers in the tower were not clearly marked and markings were not updated when the floor numbers changed following the refurbishment. Sir Martin said that all high-rise buildings should have floors clearly marked in a prominent place, which would be visible in low light or smoky conditions. Given that not all residents of Grenfell could read fire information signs, he said this should now be provided in a means that all residents can understand.

Use of combustible materials

Sir Martin said the original fire in the kitchen was no more than an ordinary kitchen fire that spread to the cladding because of “the proximity of combustible materials to the kitchen windows” – such as the uPVC frames.

He said this is a matter that “it would be sensible” for owners of other high-rise buildings to check.

He said he would “add his voice” to those who have expressed concern about the slow pace of removal work for more than 400 other tall buildings in England with aluminium composite material cladding.

A total of 97 buildings in the social housing sector and 168 in the private sector have not yet seen the work complete. Sir Martin said the work must be completed “as vigorously as possible”.

He said particular attention should be paid to decorative features, given the crucial role played by the architectural crown at Grenfell in spreading the fire around the building.

Given the decision to ban combustible materials on new buildings last year, he did not call for further restrictions on their use.

Fire service: knowledge and understanding of materials in high-rise buildings

Sir Martin raised concern that junior firefighters were not aware of the danger of cladding fires, and that the London Fire Brigade (LFB) was unaware of the combustible materials used to refurbish Grenfell Tower.

He therefore recommended:

  • That the owner and manager of every high-rise building is required to provide details of external walls and the materials used to the local fire service, and inform them of any changes
  • To ensure that fire services personnel at all levels understand the risk of cladding fires


Sir Martin said that a lack of plans did not “unduly hamper” fire services at Grenfell, as each floor was laid out in the same way. However he warned that another building with a more complex layout could pose problems. He recommended:

  • That owners and managers of high-rise buildings are required by law to provide paper and electronic versions of building plans of all high rises to local fire services
  • To ensure the building contains a premises information box, including a copy of floor plans


Firefighters were unable to use a mechanism that allows them to take control of the lifts on the night of the fire, hampering their progress and meaning residents could still use the lifts, “in some cases with fatal consequences”. Sir Martin therefore recommended:

  • That the owner and manager of every high-rise building be required by law to carry out regular inspections of any lift required for use by firefighters and the mechanism that allows them to take control of it

Section 7(2)(d) of the Fire and Rescue Services Act

The judge was concerned that inspections of the tower by the fire service before the fire were not enough to meet their responsibilities under this act. He recommended:

  • A revision of the guidance for the London Fire Brigade, and training for all officers above the rank of crew manager in inspecting high-rise buildings

Co-operation between emergency services

There was a lack of communication between each emergency service at Grenfell, with each declaring a major incident at different times without telling each other. Sir Martin recommended several changes to ensure better communication in the future.

Personal fire protection

Sir Martin decided not to issue a recommendation that individual flats be provided with fire extinguishers or fire blankets, noting concerns that this could encourage residents to fight fires rather than escape and call the emergency services.

Communication between the control room and the incident commander

While guidance calls for a “free flow” of information between a fire service control room and the commanding officer on the ground, that often does not happen. Sir Martin therefore recommended:

  • A review of policies by the LFB on this matter, including training for all officers who could serve as incident commanders and senior control room officers.
  • A dedicated communications link between the senior officer and the incident commander

Emergency calls

Even allowing for the pressure of the night, Sir Martin said that fire survival guidance calls were not handled in an “appropriate or effective way”. He therefore recommended:

  • Amending of policies and training for control room officers
  • That all fire services develop policies for multiple fire survival guidance calls
  • Electronic systems to record and display calls
  • A policy for managing a transition from ‘stay put’ to ‘get out’ and training for call handlers in delivering this change of advice

Command and control

Sir Martin said firefighters too frequently “acted on their own initiative”, resulting in a duplication of effort. He called for better policies to ensure:

  • Better control of training and deployment
  • Information is obtained from crews after they have deployed


Sir Martin made some recommendations for improvements to fire service equipment, including radios and the command support system.

Testing and certification of materials

Sir Martin said this is an issue that will be investigated “early in phase two”, along with an assessment of “whether the current guidance on how to comply with the building regulations is sufficiently clear and reliable”.

He also said the inquiry would investigate whether a ‘prescriptive’ regime of regulation was necessary. However, as these issues have not yet been examined by the inquiry he did not make any recommendations.

Grenfell Tower Inquiry: full coverage

Grenfell Tower Inquiry: full coverage

Evacuation plans should be developed for all high-rise buildings, says Grenfell Inquiry judge

Sir Martin calls for landlords to develop evacuation policies on all high-rise buildings as well as recommending an “urgent” inspection of fire doors in all properties.

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Grenfell Tower Inquiry: the recommendations

A full list of Sir Martin’s 17 recommendations, including calls for building owners to install facilities to give evacuation signals to tenants and cladding removal work to be completed “as vigorously as possible”.

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Grenfell Inquiry: ACM cladding was ‘primary cause of fire spread’ and tower did not comply with regulations, judge rules

The judge leading the Grenfell Tower Inquiry has ruled that the cladding installed on the tower did not comply with building regulations, finding that the polyethylene-cored panels were the “primary cause” of the rapid spread of flames.

Click here to read the full story

Grenfell Inquiry: round-up of Sir Martin Moore-Bick’s phase one conclusions

How the fire started, why the fire spread, what was the response from the fire brigade, emergency services and Kensington and Chelsea Tenant Management Organisation, all covered in our round-up of the Sir Martin’s conclusions.

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Grenfell Inquiry report: stay put ‘an article of faith’ within LFB

The inquiry judge criticises the London Fire Brigade’s “reluctance to believe that a building wouldn’t comply with building regulations” and claims that many lives would have been saved if the incident commander told residents to evacuate earlier.

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KCTMO chief criticised for ‘passive role’ and ‘ineffective leadership’ on night of Grenfell fire

Former chief executive of the Kensington and Chelsea Tenant Management Organisation was labelled as “essentially detached” from events on the night of the fire by Sir Martin. The company was also criticised for not passing on crucial resident information to the fire brigade.

Click here to read the full story

Grenfell Inquiry: ACM cladding was ‘primary cause of fire spread’ and tower did not comply with regulations

Despite saying that he would try not to deal with the make-up of the building in his phase one report, Sir Martin decided to make an early finding that the building breached headline regulation. He also ruled that the building suffered “total failure of compartmentation”.

Click here to read the full story

Grenfell Inquiry reaction: survivors call for implementation timeline for recommendations

Survivors group Grenfell United calls for fire service bosses to “face consequences” for failings leading up to the fire, while the London Fire Brigade, National Housing Federation and Royal Borough of Kensington and Chelsea also respond

Click here to read the full story

Recommendation rejected by Pickles as ‘disproportionate’ in 2013 repeated in Grenfell Tower Inquiry

Story reveals that as communities secretary Eric Pickles was given a recommendation after the Lakanal House Fire to ensure all high-rises “provide relevant information on or near premises” but branded a move to implement “unnecessary and disproportionate”

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Grenfell judge calls for Johnson to implement Grenfell Inquiry recommendations ‘without delay’

Grenfell judge calls for Johnson to implement Grenfell Inquiry recommendations ‘without delay’ In a letter to prime minister Boris Johnson before the inquiry was published, report author, Sir Martin Moore-Bick, calls on PM to implement inquiry recommendations “without delay”.

Click here to read the full story

Government to implement Grenfell Inquiry recommendations ‘in full’ and provide funding

Robert Jenrick, housing secretary, promises to bring in all of Sir Martin’s recommendations “without delay” and also guarantees government will pay for changes.

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Government to implement Grenfell Inquiry recommendations in full

Ministers will implement recommendations put forward in the Grenfell Tower Inquiry’s first report “in full” and “without delay”, housing secretary Robert Jenrick has confirmed.

Click here to read the full story

Stay Put: where did it come from and where do we go next?

“Stay put had become an article of faith and to depart from it was unthinkable.” These are the words of Grenfell Inquiry judge Sir Martin Moore-Bick. Peter Apps looks at where the idea came from and where we go now.

Click here to read the full story

Is your approach to fire safety reliant on faith in the system or good judgement?

The Grenfell Tower Inquiry report suggests that housing providers and the fire service have not been willing enough to plan for worst-case scenario fires in high-rise buildings. Martin Hilditch outlines how the inquiry’s report should guide thinking and practice

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