Transcript RONAN POINT

Background
• Constructed 1966 – 1968
• High-rise, high density Council-owned development
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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
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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
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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