A report carried out by consulting engineer Arup into four London apartment blocks concluded that they could have collapsed if any had suffered a gas explosion in the 50 years since they were built.
It confirmed that strengthening works – which should have been given to all UK tower blocks after the partial collapse of an east London tower block in 1968 – were not carried out, and that as a result the Ledbury Estate should not have been fitted with a central gas supply.
Southwark council, which owns the estate, now intends to strengthen the blocks and make them fully electric.
The report said: "We have found that the buildings are not robust enough for buildings with piped gas. No reinforcement was detected in the internal loadbearing walls or the internal leaf of the external loadbearing walls."
It added: "The loss of walls would undermine the support to the floor slabs immediately above and investigations of the connection between the floor slabs and wall above show that the connection is incapable of supporting the weight of the floor in tension.
"Based on the findings of the investigations undertaken, it would be impractical to strengthen the building to accommodate piped gas. The assessment also shows that the wall panels would fail under blast pressures for non-piped gas. It is therefore recommended that gas is not re-introduced in any form. It is further recommended that the gas pipes be removed, to ensure there will be no future use of piped gas."
Arup began a structural survey of the 200-home Ledbury Estate towers in Peckham on 3 July. It was commissioned by Southwark council at the request of residents who were concerned about their safety following the Grenfell Tower fire in west London on 14 June that is thought to have killed at least 80 people.
Tenants were worried about a number of cracks that had appeared in the blocks over 30 years, which appeared wide enough to allow a fire to spread. Â
Arup investigated the 14-storey blocks by taking apart two vacant apartments. At first residents were told there were "no structural safety issues" with their homes, but in August the consulting engineer informed the council that strengthening work that should have been carried out more than 40 years ago had not been done and that, as a result, the blocks were in danger of suffering progressive collapse in the event of a gas explosion.
The precedent for this kind of disaster was not Grenfell, but the structural failure of Ronan Point in 1968. This was a 22-storey block in Canning Town, east London, which suffered progressive collapse on one of its corners after a resident’s gas stove exploded. The resident in question survived, but four people living on floors below were killed.
All tower blocks in the UK should have been strengthened after that event, but evidently Ledbury was not.
On 11 August, the council turned off the gas and told tenants that they would have to move out over the coming months as strengthening work was carried out.
Arup will now carry out further tests on more flats to find out if strengthening works could save the buildings for the future. A further report will be made to Southwark council in November.
Image: The blocks near the Old Kent Road were completed in 1968 (GLA)