The architect, builders and fire engineer who worked on the disastrous Grenfell Tower refurbishment knew the cladding system would fail in a fire more than two years before 72 people were killed, emails disclosed to the public inquiry have revealed.

Staff at the architecture firm Studio E, the fire engineer Exova, the facade installer Harley, the main contractor, Rydon, discussed how the cladding system they were planning to wrap around the 120-home council block was likely to fail in the event of a fire.

“Metal cladding always burns and falls off,” one architect emailed a fire engineer in spring 2015, while the project was under way. An employee of the facade installer told a colleague: “As we all know, the ACM [combustible cladding panels] will be gone rather quickly in a fire!”

The correspondence was disclosed by Craig Orr QC, counsel for Celotex, the manufacturer of Grenfell’s combustible cladding. It came during the second day of the second phase of the Grenfell Tower public inquiry examining events leading up to the disaster.

In front of bereaved family members and survivors – including Nicholas Burton, who lost his wife, Pily, and Antonio Roncalato, who was not rescued until 6am – the inquiry also heard how the cladding panels made by Arconic, which contained a flammable polyethylene core, were chosen in 2014 to help cut £454,000 from the budget by the Kensington and Chelsea Tenants’ Management organisation, which ran the block for the Royal Borough of Kensington and Chelsea.

Timeline Key events since the Grenfell Tower fire Show The fire breaks out in the early hours of the morning, prompting a huge response from emergency services, who are unable to bring the fire under control or prevent a severe loss of life. The then Conservative prime minister, Theresa May, visits the scene and orders a full inquiry into the disaster, and the government promises that every family will be rehoused locally. The communities secretary, Sajid Javid, orders an emergency fire safety review of 4,000 tower blocks across Britain, and it will emerge that 120 tower blocks have combustible cladding. Scotland Yard launches a criminal investigation into the Grenfell fire. The chancellor, Philip Hammond, says the cladding used on Grenfell Tower was banned in the UK. The retired judge Sir Martin Moore-Bick is appointed to lead the public inquiry. Kensington and Chelsea council’s first meeting since the disaster is abandoned after the council fails in a bid to ban the media from attending. Survivors have their first official meeting with the police and coroner. The inquiry formally opens. As the final death toll is confirmed to be 71 people, it is revealed that hundreds of households are still living in hotels. In defensive testimony at the inquiry, London fire brigade commissioner Dany Cotton said she would not change anything about the way the brigade responded to the Grenfell disaster, provoking anger from both survivors and the bereaved. Grenfell survivors and the bereaved expressed frustration at Scotland Yard after they admitted no charges were likely until 2021. The public inquiry report concludes that fewer people would have died had the fire brigade been better prepared. Leader of the House of Commons Jacob Rees-Mogg is forced to apologise after stating that victims of Grenfell did not use "common sense" and leave the burning building. Grenfell cladding firm Arconic reveals it has spent £30 million on lawyers and advisors defending their role in the disaster. The second phase of the Grenfell Tower inquiry begins. Stacee Smith and Grace Mainwaring

The companies involved in the refurbishment have repeatedly sought to point blame at each other and at the system for testing the fire safety of materials. That pattern, described as a “merry-go-round of buck-passing” by Richard Millett, the counsel to the inquiry, continued on Tuesday.

Arconic said it was not its responsibility “to decide if the product was appropriate to use on a particular project or in a particular configuration”. That was down to designers, contractors and fire engineers. Celotex said its insulation was sold as combustible and its use was down to “a myriad of failings on behalf of the designers, contractors, consultants and building control inspectors”. Both firms insisted they were not shifting blame but rather describing the reality of the balance of responsibility in the construction process.

On behalf of Celotex, Orr introduced email evidence that began with Daniel Anketell-Jones, a facade engineer at Harley, writing to his managing director, Ray Bailey, about the building of fire-stopping into the facade to prevent fire spread.

“There is no point,” Anketell-Jones told Bailey on 27 March 2015. “As we all know, the ACM will be gone rather quickly in a fire!”

Four days later, Terry Ashton, of Exova, emailed Neil Crawford, at Studio E: “It is difficult to see how a firestop would stay in place in the event of a fire where external flaming occurred as this would cause the zinc cladding to fail.”

Crawford replied: “Metal cladding always burns and falls off.”

Tony Pearson, also of Exova, told Ashton on the same day: “However, if significant flames are ejected from the windows, this would lead to failure of the cladding system, with the external surface falling away and exposing the cavity.”

In a fourth email, Crawford looped in Simon Lawrence, at Rydon.

“Each of Harley, Studio E, Exova and Rydon was openly acknowledging in these emails that the cladding would fail in the event of a fire with external flaming,” said Orr. “That, tragically, is what happened.”

In its opening submission, Arconic did not comment on a key conclusion of the inquiry’s first phase that its panels were the main cause of fire spread at Grenfell. Stephen Hockman QC, counsel for the firm, said he would also “resist the temptation” to comment on emails disclosed on Monday showing how, before the fire, staff feared its ACM panels were “unsuitable for use on building facades” when folded into cassettes, as they were on Grenfell.

The panels had a fire rating of E when B was the minimum required for a facade in Europe. In 2015, staff again warned they were “dangerous on facades” and said safety certifications were often “obtained largely for marketing purposes”.

Hockman said the panels were capable of achieving class B performance, but there was no guarantee that would always be achievable. Harley had told the inquiry it placed its confidence in the performance certificates.

The inquiry continues.