CROSS Safety Report
Cantilevered brickwork - fatal collapse during construction
This report is over 2 years old
A blade of 270mm cavity brickwork in a temporary condition fell and killed a bricklayer after sixteen scaffold planks were leant against the wall on the side remote from the bricklayer.
Key Learning Outcomes
For construction professionals:
It is good practice to carry out a risk assessment and method statement (RAMS) for all construction activities. This can ensure the sequencing of work activities are carefully considered, planned and temporary works provided if necessary.
Regular toolbox talks are a good way of engaging with work crews and highlighting any risks associated with work activities
For civil and structural design engineers:
Careful consideration is required for the design of masonry walls, particularly in the temporary stage because there is no redundancy and relatively small loads at the tip can precipitate failure
If a masonry wall relies on support from an adjacent wall in the permanent condition, highlight this on the drawings to bring it to the contractor’s attention
Any temporary work issues or requirements should be highlighted in risk registers and on construction drawings
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A reporter from overseas describes how, in a block of flats consisting of load bearing brickwork and concrete floor slabs, a blade of 270mm cavity brickwork was built off the slab at a one course step in the slab between living rooms and outside balconies. There was a damp proof course, Z shaped, between the slab and the brickwork.
The blade was 2.7m high and 1.4m wide and eventually would have been abutted by perpendicular 230mm party walls on its centre line on both sides. It would also support a roof that would provide lateral stability. After the top lift of brickwork was two days old a bricklayer started setting out the base course of one of the abutting walls. While he was doing this a labourer leaned sixteen scaffold planks against the wall on the side remote from the bricklayer. The wall fell and killed the bricklayer.
According to the reporter:
The brickwork would have been stable if at least part of one of the abutting walls had been constructed integrally with the blade of brickwork
The wall would not have been stable under design wind loads (for temporary structures) and should have been braced for this reason
Had this been the case the accident would probably not have occurred. One storey high temporarily cantilevering walls are not commonly braced for wind loads but perhaps should be.
All operatives interviewed after the incident said the level of site supervision and safety was excellent. A progress photo which included the fatal wall was taken 10 to 20 minutes before the accident and there were no planks placed against the wall at that time.
Note that legal proceedings in this case have been completed.
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Expert Panel Comments
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Alas the temporary stability of all forms of structure continues to be an issue of concern. There are many reports of walls or other structures toppling under accidental loading when in an unfinished state. All structures should remain stable and able to transmit forces adequately at all stages of the construction (and arguably, deconstruction). Greater awareness of the risks through education, formal or through experience, is important.
Cantilevers should always ring alarm bells particularly in the temporary stage because there is no redundancy and relatively small loads at the tip can precipitate failure. If the designer knew that the construction sequence would lead to an unstable wall, then he should have either redesigned the wall or made the risks clear on the drawings.
Cantilevers should always ring alarm bells particularly in the temporary stage because there is no redundancy and relatively small loads at the tip can precipitate failure
If it was a ‘normal construction stage’ then, as it appears the court held, the contractor should have considered the various de-stabilising modes (wind and other lateral loads). This emphasises that common construction operations can lead to dangerous situations and constant awareness is necessary.