Grenfell Tower | Warning of ‘horrible’ demolition challenge

Demolishing Grenfell Tower will be “challenging” and require very careful operations, an expert has warned.

Ministers are expected to reveal their decision on the future of the fire-ravaged building this month, with reports over the weekend suggesting they had resolved to order its demolition.

But National Federation of Demolition Contractors chief executive Howard Button told NCE it would not be straightforward to remove the tower from the landscape.

“It could be a very weakened structure,” he said of the remaining portion of the West London residential tower where 72 lives were lost in a blaze in June 2017. “The rebar could be in a very bad state. The structural stability of the building must have degraded.”

Button added: “It must be a horrible building to go into. I wouldn’t want to be going in and clearing it. It is going to be very challenging.”

Following the devastating fire four years ago, the precise scientific calculations required for effective explosion or implosion would be extremely difficult, Button warned. He added that certain pieces of the building fabric may need to be preserved for further investigation.

“It will most likely be a very controlled, top-down demolition,” he said. “The existing scaffold could be used, supported with propping, and a crane to lift debris out. Then remotely operated mini machines could be used by people a few metres away from the workface. Munchers and breakers would be attached to dismantle the building floor by floor.”

The high profile nature of the job will add further complications. “No-one wants people looking over their shoulder while they work,” said Button. “Some firms will be put off by that.”

However, the UK demolition industry has more than enough talent and experience to handle the job, he added. “The top-down process is ingrained now, it is the norm in central London. Whoever does it will know what they are doing and there won’t be any problems they haven’t foreseen.”

A report put together by Atkins told the government earlier this year that the condition of Grenfell Tower was worsening.

“The fire had the effect of spalling concrete from the underside of the floor slabs, most widespread from the tenth floor upwards, and also from many columns and areas of wall,” said the study. “As a result, the reinforcement is left exposed in many areas.

“As a result of exposure to the elements, spalling of concrete will continue, through the expansion of corroding reinforcement and absorbed water freezing in the winter months. Without this concrete in-place, the reinforcement becomes increasingly ineffective. Condensation forming on the structure surfaces exacerbates this deterioration.

“Better ventilation is being considered to mitigate this but with the building being effectively open to the elements it is not possible to entirely prevent condensation and moisture from entering the tower.”

The report added that seasonal thermal movement of the building and other environmental factors contributed to “on-going structural deterioration”.

“The rate of deterioration and expected life of the building is very difficult to quantify with any degree of certainty, however, what can be categorically stated is that the condition of the building is worsening,” it concluded.

A government spokesperson said this week that no decision had yet been taken on the future of the tower.

The spokesperson added: “Following important independent safety advice from structural engineers, we are engaging closely with the community as we consider the evidence including the safety concerns raised, and what the future of the Grenfell Tower should be.

“We have now published this advice to ensure those most affected have access to the information that will inform a decision on the Tower, before one is reached.”

Source: New Civil Engineer

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