Ronan Point — A Gas Explosion That Peeled a Tower’s Corner and Defined Progressive Collapse

At about 5:45 on the morning of 16 May 1968, a domestic gas explosion on the eighteenth floor of Ronan Point — a 22-storey precast-concrete tower in Canning Town, East London, occupied for barely two months — blew out a load-bearing corner wall panel and collapsed the building’s entire south-east corner, floor by floor, from roof to ground. Four people died and seventeen were injured; a fifth victim later died of injuries. The official inquiry, chaired by Hugh Griffiths QC with engineers Sir Alfred Pugsley and Sir Owen Saunders, found the explosion relatively small but the tower’s large-panel design devoid of effective ties between components and of any alternative load path, so the loss of one corner panel removed the support for everything above it. The Tribunal named the mechanism “progressive collapse.”

The blast itself was modest. Ivy Hodge struck a match to light her gas stove, unaware that a leaking connection had filled the kitchen with gas overnight. The resulting overpressure has been estimated at well under 10 psi — enough to knock her unconscious and blow out windows, but far below the force needed to threaten a properly tied structure. It pushed out the non-redundant load-bearing flank wall panels of the living room, which carried the four storeys of identical flats above. With their support gone, floors 19 through 22 fell onto floor 18; the falling debris overloaded the floor below, which dropped onto floor 17, and the corner “unzipped” to the ground.

The Larsen-Nielsen large-panel system joined precast walls and floors with a sparse arrangement of bolts and in-situ concrete, relying heavily on friction and the weight of panels above. There were no continuous steel ties to carry load around a missing member, and no frame to catch a dropped span. The design had been conceived for buildings far shorter than 22 storeys. When the tower was dismantled in 1986, investigators found bolts missing or barely tightened and joints meant to hold structural concrete stuffed with rubbish and newspaper. What makes Ronan Point the founding case of disproportionate-collapse design is not the gas leak — gas leaks are ordinary — but the structure’s response to a small, foreseeable insult. The Griffiths Tribunal concluded the behaviour was inherent in the design, not a product of the explosion’s size, and the lesson was permanent: a building must not collapse out of all proportion to its initiating cause.