The architects of the Grenfell Tower refurbishment, completed in 2016, specified cladding that did not burn but that material was used only on the ground floor, where nobody in the block lived.

Non-combustible concrete panels were fitted to the base of the building’s concrete columns, while plastic-filled panels, described by industry sources as about twice as cheap, were used for the upper floors of the building, planning documents reveal.

A leading fire safety expert has told the Guardian that fewer people might have died if the concrete panels had been extended upwards, although questions remain over whether the heavier material could have been fitted without requiring structural improvements to the original concrete frame of the tower in north Kensington, London.



“It would have saved lives,” said Arnold Tarling, a chartered surveyor at Hindwoods. “The fire may have scorched it and the insulation. It wouldn’t have spread over the whole of the building like it did.”

Flames could be seen spreading up the original columns in the blaze, which killed at least 80 people. The spread of the fire has been widely blamed on the cladding, which had a layer of plastic filler that was not fire retardant.

The glass reinforced concrete (GRC) panels that were used at the base of Grenfell were not flammable. GRC has been tested at the highest fire rating, of A1, and the panels have been used on luxury apartment complexes, including high rises.



However, industry sources said GRC panels cost about twice as much as the aluminium panels used, which had a polyethylene core. The fire-retardant panels could have increased the refurbishment cost by at least £1m and could only have been erected if the existing building had been shown to be capable of bearing the load; if it wasn’t, this would have required reinforcement works, further increasing costs. It is not known if this was explored.

The decision not to use fully fire retardant material across Grenfell Tower has raised concerns about the impact of the cost cutting on the refurbishment project carried out for the Kensington and Chelsea Tenant Management Organisation (KCTMO).

Documents emerged last week showing that contractors, supposedly under pressure, slashed cladding costs by almost £300,000.

An “urgent” email on 16 July 2014 from KCTMO’s project manager told its quantity surveyor, Artelia: “We need good costs for Cllr Feilding Mellen” [referring to a former deputy leader of Kensington and Chelsea].

The response included a proposed £293,368 cut to the cost of the cladding. Zinc cladding with a fire resistant core was then replaced with cheaper aluminium panels without the same fire resistance – which in the end failed to contain the blaze.

Earlier KCTMO had balked at estimates from the contractor Leadbitter rating the project in 2012 at a cost of £11.3m and had appointed Rydon instead, on a tighter budget of £8.7m. That followed a “value engineering process”, according to a report by Kensington and Chelsea’s housing and property scrutiny committee.

KCTMO declined to comment on why GRC was not used further up the block. A spokesman said the organisation had “put on hold all requests for disclosure of relevant information”. He added: “We recognise our responsibility to ensure that the investigative process is not hampered or undermined in any way.”

GRC has recently been used on a pair of new 27-storey and 28-storey student accommodation towers in Wembley and King’s Cross, London.

Rydon, the contractor, said: “The material used on the ground floor was GRC. This was the material that was outlined in the architectural spec and agreed by the client.” The architects, Studio E, did not respond to request for comment.