Grenfell and Construction Industry Reform

A Guide for the Construction Professional

Steve Phillips, Jim Martin

• Verlag: Routledge
• Jahr: 2021
• ISBN:
  9781000437232
• Auflage: 1
• Thema: Architecture
• Thema: Pratique professionnelle en architecture

This book sets out the urgent changes to practices and behaviours required to build a new building safety regime in the UK and prevent a similar tragedy to the fire at Grenfell Tower from reoccurring.

The inquiry into the fire and the independent Hackitt Review revealed deep-rooted and unpalatable truths about the current state of the UK construction industry. Dame Judith Hackitt was scathing in her assessment of the construction industry denouncing it as "an industry that has not reflected and learned for itself, nor looked to other sectors" and defining the key issues as ignorance, indifference, lack of clarity on roles and responsibilities and inadequate regulatory oversight and enforcement tools.

Invaluable for all construction professionals who wish to take greater responsibility for the safety of residents in their buildings, this book explains why these major safety reforms are required, how they are to be achieved and the progress towards them to date.

1 The Grenfell Tower fire

DOI: 10.1201/9781003092803-1

Background

Grenfell Tower is approximately 67 m in height and has 25 storeys including a basement. The building comprises an in situ concrete structural frame with a central reinforced concrete core, reinforced concrete floors and perimeter reinforced concrete columns. Originally, pre-cast concrete spandrel panels formed the cladding to the upper 20 storeys of the building, with sliding windows units of mill-finished, single glazed aluminium and non-structural white window infill panels. At the top of the building was a pre-cast architectural crown with tapered pilasters at the tops of the columns and a ring of freestanding concrete beams. In the central core of the building was a single staircase and two lifts serving each floor of the tower. The residential flats occupied floors 4–23 with 6 flats on each floor. The flats were separated with reinforced concrete cross walls. The lower levels of the building were designed for use by the local community.¹ Figure 1 shows the external view of Grenfell Tower prior to the refurbishment works being carried out.

Figure 1 Grenfell Tower Prior to the Refurbishment Works.

(Credit: Dr Lane supplemental report [BLAS0000008] p. 6 Fig. 8.2)

The refurbishment

Grenfell Tower is owned by the Royal Borough of Kensington and Chelsea (RBKC), but from 2009, the management of the building became the responsibility of an independent company, The Kensington and Chelsea Tenant Management Organisation (KCTMO). Between 2012 and 2016, an extensive regeneration project altered the building both internally and externally. These works included the refurbishment of the lower part of the building and the creation of nine new flats. Building services work was undertaken throughout the building including the installation of a new heating system and the modification of the original smoke control system to become a new combined environmental and smoke control system. The most significant works were the over- cladding of the existing building with a new insulation and rainscreen cladding system.

The use of over-cladding on tower blocks was a standard solution used by Local Authorities at the time to meet their obligations under the Decent Homes Programme² to ensure that all homes within their stock should be in a good state of repair and have effective heating and insulation. The design and access statement in the planning application for the works at Grenfell Tower stated that the changes to the envelope of the building were part of an integrated solution to tackle the building’s inefficient energy performance. The main objectives for the proposed over-cladding system were set out as:

• A dramatic improvement in heat loss with new insulation and air sealing which will generate significant energy savings
• New windows units which can naturally vent the building throughout the year, provide natural daylighting, and be safely cleaned from the inside
• Improvement in the appearance of the tower

Originally, Leadbitter Construction were the preferred contractor to carry out the proposed works, but at £11.278 million (inclusive of fees), their bid was £1.6 million above the proposed budget. After a further procurement process in June 2014, Rydon Maintenance Limited were appointed as the design and build contractor with a bid of £8.7 million. They contracted Harley Facades Ltd as their cladding sub-contractor. The external cladding was supplied by Arconic with the two main suppliers of insulation being Kingspan and Celotex. Studio E was the architect for the main refurbishment works, and the Employer’s agent/Quantity Surveyor was Artelia Projects UK Limited. A degree of specialist fire engineering services was provided by Exova Warrington Fire Consultants.

The project was funded by RBKC, and the Department of Building Control at RBKC acted as the building control authority. They undertook a number of inspections between August 2014 and 2016, and the building certificate for the completion of works being signed off on 7 July 2016.

In addition to the main refurbishment works, the KCTMO had, between 2011 and 2013, carried out a programme of replacing 106 entrance doors to the flats owned by RBKC tenants with fire doors that complied with the relevant legislative fire safety standards. The manufacture of the doors and the installation works were carried out by Manse Masterdor.

The fire

In the early hours of the morning of 14 June 2017, a fire reported to have started in a fridge-freezer located in Flat 16 on the fourth floor of Grenfell Tower. The fire moved beyond the kitchen as flames and hot gases caused the uPVC jamb of the kitchen window to deform and collapse. This provided an opening for the flames to pass into the cladding façade system on the outside of the building. The cladding consisted of aluminium composite material (ACM) rainscreen panels bonded to a central polyethylene core which, being highly combustible, was the primary cause of the fire spread. It spread extremely rapidly around the outside of the building, both vertically up the tower columns and laterally along the cladding above and below the window lines.³ The fire moved across the eastern side of the building to the north face of the tower and into the majority of the other apartments in the tower block. The principal catalyst for the fire spreading horizontally and downward was dripping polyethylene emanating from the architectural crown of the building and from the spandrel and column panels. The polyisocyanurate (PIR) and phenolic foam insulation boards, located behind the ACM panels, contributed to the speed of the vertical flame spread.

Tragically, Grenfell Tower had a “stay put” fire policy in place which means that the building had been designed to contain any outbreak of fire within the individual flat where the fire ignited until the fire service arrived to extinguish the fire. However, in reality, there proved to be little resistance to the spread of fire making it extremely difficult to extinguish, which resulted in the death of 72 occupants.⁴ The death toll was exacerbated by the volumes of smoke produced from the burning facade. The smoke appears to have entered the building through unprotected openings even before the contents of each affected flat were ignited and the high toxicity of the smoke from the facade is an important factor in the scale of the tragedy. Smoke inhalation is recognised as the most common form of death and injury from fire in the UK.⁵ On exposure to the smoke, the victim becomes unconscious, and unless they are rescued from the building, the effect of the smoke is lethal.⁶

Public inquiry

The public inquiry was called by the Prime Minister, Theresa May, on 15 June 2017. It was chaired by a retired judge, Sir Martin Moore-Bick, and its primary purpose was to establish the facts of how the fire had occurred to prevent a similar tragedy happening in the future. Phase 1 of the inquiry considered what happened on the night of the fire. It commenced on 14 September 2017 and concluded on 12 December 2018.

A number of expert witnesses gave evidence at the Public Inquiry between 20 and 29 November 2018:

• Professor Luke Bisby spoke about the ignition of the facade materials and the external spread of fire.
• Professor Jose Torreo addressed the fire spread throughout the building.
• Dr Barbara Lane considered the fire protection measures within the building.
• Professor Niamh Nic Daeid gave evidence around the cause and spread of the fire in the flat of origin, Flat 16, and the spread of fire within and from Flat 16.
• Professor David Purser provided evidence on the production of toxic gases and the consequences of inhaling toxic gases in such circumstances, which were the likely causes of incapacitation and death at Grenfell Tower.

The Phase 1 inquiry report was published on 30 October 2019, and Moore-Bick concluded that

there was compelling evidence that the external walls of the building failed to comply with Requirement B4(1) of Schedule 1 to the Building Regulations 2010, in that 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.⁷

The Phase 2 inquiry commenced in February 2020 with the overarching aim of examining the events that lead to the fire. These events included the refurbishment of the tower, testing of the external cladding system, compliance with the building regulations and the role of central and local governments. The inquiry was suspended in March 2020 due to COVID-19 lockdown restrictions and did not recommence until 7 September 2020.

In the following sections, the evidence provided in Phase 1 of the inquiry is used to explain in more detail how the design of the refurbishment works, and the choice of materials used in those works contributed to the spread of fire and smoke throughout Grenfell Tower. The final section also reviews the “stay put policy” that was in place at the time of the fire and how this contributed to the tragedy.

Aluminium composite cladding material

The renovation of Grenfell Tower involved the building being externally clad with a ventilated rainscreen system designed to protect the building from direct rainfall with a cavity behind the outer skin to ensure that any rainwater was collected and drained away to prevent it from penetrating into the building. The rainscreen panels were known as “Reynobond 55 PE” Aluminium Composite Panels (ACP). Each panel consisted of two 0.5 mm thick aluminium sheets bonded to a 3 mm central plastic (polyethylene) core. Behind the panels was a layer of insulation fixed directly to the building. On the spandrels this, predominantly, consisted of two 80 mm layers of Celotex RS5000 PIR polymer foam with one 100 mm layer of the same insulation being affixed to the columns.

Before being installed, the panels were fitted into “cassettes” which were hung onto aluminium or steel supports affixed to the concrete structure. This left a 50 mm cavity between the inside face of the rainscreen panel and the outer face of the insulation to allow the ventilation and drainage of any rainwater that penetrated the gaps between the external cladding panels. Smaller cavities, with no design function, were also formed between the face of the insulation board and the columns. The problem with PIR foams is that the...