Grenfell: Official phase 1 report blames materials combinations

London – The formal publication of the first phase of the Public Inquiry into the Grenfell Tower fire was published this morning. 
It follows a leak of parts of the report yesterday in the Daily Telegraph Newspaper. 
You can view the whole first phase report on the inquiry's website. Here are some of the key summary points: 

1. Start of the fire and its escape from first flat  

The fire was started by an electrical fault in a large fridge-freezer in the kitchen of Flat 16

a. The fire is most likely to have entered the cladding as a result of hot smoke impinging  on the uPVC window jamb, causing it to deform and collapse and thereby provide an  opening into the cavity between the insulation and the ACM cladding panels through  which flames and hot gases could pass.

b.  It is, however, possible (but less likely) that  flames from the fire in the fridge-freezer passed through the open kitchen window and  impinged on the ACM cladding panels above

2. Initial progress

Once the  fire had escaped from Flat 16, it spread rapidly up the east face of the tower. It then spread  around the top of the building in both directions and down the sides until the advancing  flame fronts converged on the west face near the south-west corner, enveloping the entire  building in under three hours.

Three factors affected the progress

a. The principal reason why the flames spread so rapidly up, down and around the building was the presence of the aluminium composite material (ACM) rain screen panels with polyethylene cores, which acted as a source of fuel. The principal mechanism for the spread of the fire horizontally and downwards was the melting and dripping of burning polyethylene from the crown and from the spandrel and column panels, which ignited  fires lower down the building. Those fires then travelled back up the building, thereby  allowing the flame front to progress diagonally across each face of the tower.

b. The presence of polyisocyanurate (PIR) and phenolic foam insulation boards behind the  ACM panels, and perhaps components of the window surrounds, contributed to the rate  and extent of vertical flame spread.

c. The crown was primarily responsible for the spread of the fire horizontally, and the  columns were a principal route of downwards fire spread.

3. Compliance with Building Regulations

There was compelling evidence that the external  walls of the building failed to comply with the Building  Regulations 2010. They did not adequately resist the spread of fire having regard to  the height, use and position of the building. On the contrary, they actively promoted it. It will  be necessary in Phase 2 to examine why those who were responsible for the design of the refurbishment considered that the tower would meet that essential requirement.

4. The second phase

Design and choice of materials will be a key theme of the second phase which starts in early 2020. 
The report states that 'a number of aspects of the design of the refurbishment and the choice of materials will need to be examined.

The report goes on to say that the choice of 'ACM panels with a polyethylene core, the choice of combustible  insulation and XPS window infill panels, a design which incorporated many vertical channels and the decision to incorporate an architectural crown composed of ACM fins, all of which made a major contribution to the extent of the fire, are just examples' of areas that need to be examined more thoroughly.