This was one of the main conclusions of a Health and Safety Executive report into the 1995 collapse of an office block built in 1969-70 at Ashford, Middlesex, which killed four men.
The warning was given by DETR Building Regulations head Paul Everall, who wrote to the chief executives of all metropolitan and county councils, as well as approved building inspectors throughout the UK.
The HSE report, Collapse of a Three-Storey Building, gives a shocking account of how two storeys were added to a single-storey building.
The building collapsed during a refurbishment for client Hall and Co by Portsmouth-based contractor John Lay & Co.
The collapse was caused by the failure of one or more lightweight concrete blocks that had originally formed the base of a parapet wall at the top of the single-storey building.
When contractor EP Wickens and Sons, which built the original structure, added the upper floors in 1970, brick columns were built on top of the lightweight concrete blocks.
The defects reflect gross incompetence or total irresponsibility of those engaged in the original construction
Health and Safety Executive Report
The report says that these lightweight blocks had a “crushing strength” of 2.6 N/mm2, compared with the 37.4 N/mm2 that the bricks in this area should have had. “Blocks of this strength were completely unsuitable for use in this location,” says the report.
For years there was no problem, because the load of the bricks above was dispersed through the building by the surrounding blockwork and window frames. As the refurbishment began, workers began to remove this blockwork, greatly increasing the load placed on the lightweight concrete blocks. This led to the “rapid and catastrophic collapse of two-thirds of the building”.
The report’s account of the collapse is particularly harrowing. On the morning of 1 August 1995, carpenter Peter Berwick and labourers Richard Barnes and Mark Malloy had started to break out blockwork, and at 2pm Berwick called over a bricklayer to show him a 100 mm thick lightweight concrete block at the base of a brick column with bricks overhanging
it by 50-75 mm. The men stopped work, site agent Ron Martin was fetched and minutes later the building collapsed, killing Berwick, Barnes, Malloy and Martin.
The HSE believes that had the building been built after 1970, it would have been less prone to such a sudden collapse because of stricter building regulations in force at the time. These regulations, which were designed to prevent buildings collapsing suddenly because of local faults, were introduced in the wake of the 1968 collapse of Ronan Point tower block in Newham, east London.
The HSE report continues: “The defects discovered in the brick columns in this building reflect either gross incompetence or total irresponsibility on the part of those engaged in the original construction work and its management. Everyone in the construction industry needs to be vigilant against such blatant malpractice.”