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Background • Constructed 1966 – 1968 • High-rise, high density Council-owned development • • • • to meet the housing needs of the time 22 storeys, 110 flats Each floor built identically Built using the Larsen-Nielson method One of 7 of towers built in the area in the same way Larsen-Nielson Method A Large Panel System Minimises on-site construction with precast panels Every panel is load-bearing and transfers the load directly to the floor/panel below Little redundancy Suitable for buildings up to ~6 storeys –Ronan Point had 22 storeys! A minor gas explosion 4 floors from the top blew out 1 wall Every floor on the South-East corner fell onto the floor below The damage was localised to this corner and the building remained standing How big an explosion? Car Tyre 20psi Bicycle Tyre 100psi Air in lungs 1.5psi Gas explosion in Ronan Point <10psi Explosion was so small, the woman who lit the cooker did not damage her hearing! What was wrong? Design Written in 1952, building codes were out of touch with the construction industry Gave poor guidance for high-rise development Lateral loading barely considered Only required to withstand a wind-loading of 63mph – quite likely during the 60 year lifespan of a 22 storey building No alternative load paths What was wrong? Construction Larsen-Nielson relies on good workmanship This was lacking in Ronan Point “Mortared” joints filled with newspaper and dirt Specialist bolt jointing technique carried out by unqualified workers Lack of supervision 4 fatalities and 17 injuries Widespread panic over the safety of all high-rise buildings Full inspections of all similar buildings ordered by the Ministry of Housing to allay people’s fears Many buildings found to be unsafe Immediate ban on using gas cookers in high-rise buildings Effect Major revision of the Building Codes w.r.t. lateral loading, load paths, progressive collapse and fire/gas Demolition or repair of unsafe towers £millions in cost to the taxpayer Move away from high-rise flats Restriction on the use of gas in tall buildings Ivy Hodge had to move house (again) Ronan Point demolished in 1986