The BBC reports that the council, which has been a focus of anger after the devastating fire, had originally planned to use zinc cladding, with a fire-resistant core.
At least 80 people died in the fire which ripped through a tower where around 500 people were sleeping, shortly after midnight on June 14.
While the cause of the fire was a faulty fridge-freezer, the cladding has been blamed by fire experts as a major contributing factor in the spread of the fire.
The Times newspaper and the BBC reported having seen documents where councillors put forward proposals to lower the cost of Grenfell Tower's renovation.
At a council meeting in July 2014, in an effort to drive down costs, aluminum cladding with a plastic core was chosen instead, saving £293,368.
It was part of a list of cost saving measures given to the contractors to reduce the overall cost of renovation from £9.2 million to £8.5 million.
At the time, both types of cladding had the same fire safety rating, however recent tests on cladding carried out by the government show that all 137 cladding samples sent for testing, from 41 local authority areas have failed fire tests.
Residents, who had been told the building would have zinc cladding were not notified of the changes.
Even on the day of the fatal fire, many residents who spoke to getwestlondon said the cladding was zinc.
The news comes just a day after the council attempted to bar the public and press from a cabinet meeting on Grenfell.
After disputing the council's decision, a High Court order allowed members of the press access to the meeting, but council leader Nicholas Paget-Brown decided to close the meeting after giving a short speech.
He said the meeting was closed on legal advice that if the press reported on the issues being discussed, it would prejudice the inquiry into the fire.
Downing Street has joined in on the criticism of the bizarre meeting, with a spokesman for Prime Minister Theresa May saying: "The High Court ruled that the meeting should be open and we would have expected the council to respect that."
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