Ronan Point
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Ronan Point was a 23-storey tower block in Newham, East London, which suffered a fatal partial collapse due to a natural gas explosion 16 May 1968.
Ronan Point, named after Harry Ronan (a former Chairman of the Housing Committee of the London Borough of Newham), was part of the wave of tower blocks built in the 1960s as cheap, affordable prefabricated housing for inhabitants of the West Ham region of London. The tower was built by Taylor Woodrow Anglian, using a technique known as Large Panel System building or LPS. This involved casting large concrete prefabricated sections off-site, then bolting them together to construct the building.
Building started in 1966, and construction was completed on 11 March 1968.
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[edit] Construction
There are three main methods of constructing tall buildings:
- Steel
- Here a set of steel members are fixed together to make the frame of the building. The World Trade Center was an example of this type of building.
- In situ concrete
- Here a mould or formwork is made using wood or another similar material. Steel reinforcement is placed in the formwork, then concrete is poured into the mould and then allowed to set. The mould is removed, and may be reused to make identical castings in other areas of the building. The resulting building is a solid block of concrete made from multiple castings poured on top of one another.
- The use of prefabricated concrete members - large panel systems
- Here a set of concrete parts are made at a factory and are transported to the site, where they are lifted into place with a crane and then joined together. This joining process requires precision and skill, and it is thought that a failure to join the panels correctly led to the Ronan Point collapse. The structure of Ronan Point and other LPS buildings of the time relied on gravity holding everything together. [1] [2]
[edit] Collapse
Only a few weeks after the occupants had moved in, a gas explosion demolished a load bearing wall, causing the collapse of one entire corner of the building. Four people were killed in the collapse, and seventeen were injured.
At approximately 5:45am on the 16 May 1968, 56-year-old cake decorator Ivy Hodge went into her kitchen in flat 90, a corner flat on the 18th floor of the building, and lit a match to light the stove for her early morning cup of tea. This sparked a gas explosion, which blew out the load bearing flank walls, removing the structural supports to the four flats above. It is believed that the weakness was in the joints connecting the vertical walls to the floor slabs. Under the action of gravity the flank walls fell away, leaving the floors above unsupported. This caused the progressive collapse of the whole south-east corner of the building.
Because the building had just opened, three of the four flats immediately above Miss Hodge's were unoccupied. Out of the 260 residents of the building, four people were immediately killed in the collapse, and seventeen were injured, including a young mother who was stranded on a narrow ledge when the rest of her living room disappeared. Miss Hodge survived, despite being blown across the room by the explosion - as did her gas stove, which she took to her new address after the explosion.
Although Ronan Point was repaired using strengthened joints, public confidence in the safety of residential tower blocks had been irreparably shaken. Within a couple of decades, this lack of confidence, plus the mounting social problems manifesting themselves within such developments, led to many tower blocks being demolished. Ronan Point itself was pulled down in 1986, and replaced with two-storey housing.
[edit] Effect on legislation
The partial collapse of Ronan Point led to major changes in the building regulations. The first of these came with the 5th Amendment to the Building Regulations in 1970. These are now embodied in Part A of the Building Regulations and cover Disproportionate Collapse.
Immediately after the publication of the report the Government brought out interim measures to ensure the safety and integrity of buildings in the event of an explosion. All new buildings constructed after November 1968 and over 5 storeys were required to be able to resist an explosive force of 5 lbs per square inch (psi). Existing buildings were allowed to resist an explosive force of 2.5 psi, provided that the gas supply was removed and flats were refitted for electric cooking and heating. The gas supply was removed from Ronan Point and the other eight blocks on the estate.
Newham Council voted to demolish Ronan Point in the autumn of 1984. The whole nine blocks on the estate containing 990 flats were demolished and the area rebuilt with two-storey houses with gardens.
Many other large panel system buildings like Ronan Point have been demolished. The Building Research Station published a series of reports in the 1980s to advise Councils and building owners on what they should do to check the structural stability of their LPS blocks.
1. The Structure of Ronan Point and other Taylor Woodrow-Anglian Buildings 1985 ISBN 0-85125-342-3
2. Large panel system dwellings: preliminary information on ownership and condition 1986 ISBN 0-85125-186-2
3. The structural adequacy and durability of large panel system dwellings 1987 ISBN 0-85125-250-8
The contents of 2 relied on local authorities sending returns in the Ministry of Housing in 1968/69. This was not exhaustive, with many authorities failing to do so and thus not having their blocks assessed after the issue of interim structural methods by the MOHLG in 1968/69. Among these authorities were Birmingham, Lambeth and Southwark in London. Birmingham owned over 300 LPS blocks and when these were assessed in 1998 it was found that a number which did not meet 5 psi still had a piped gas supply. A number of these blocks were demolished.
The London Borough of Southwark owns the largest LPS estate in the UK - the Aylesbury Estate - which has a piped gas supply, and it has been queried whether the existing structure is strong enough to resist a 5 psi explosion.
A number of books have covered the collapse of Ronan Point, including Collapse: Why Buildings Fall Down by Phil Wearne ISBN 0-7522-1817-4. This was written to accompany the TV series of the same name shown on Channel 4 in early 2000.
