CROSS Safety Report
Fatal wall collapse at school due to wall climbing
This report is over 2 years old
Overview
This report has been provided by the Health and Safety Executive (HSE) and once again highlights the potential dangers of freestanding masonry walls.
Key Learning Outcomes
For civil and structural design engineers:
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Consider what reasonably foreseeable loads could be applied beyond the code minimum values on elements such as freestanding walls
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Carefully assess the stability of any freestanding walls while carrying out condition assessments and inspections
Full Report
Find out more about the Full Report
The Full Report below has been submitted to CROSS and describes the reporter’s experience. The text has been edited for clarity and to ensure anonymity and confidentiality by removing any identifiable details. If you would like to know more about our secure reporting process or submit a report yourself, please visit the reporting to CROSS-UK page.
This report has been provided by the Health and Safety Executive (HSE) and once again highlights the potential dangers of freestanding masonry walls. It draws attention to a possible mechanism whereby a limited number of persons can impose actions on walls or partitions in excess of the values contained in the Eurocode. The findings arise out of a Fatal Accident Inquiry into the tragic death of a school pupil in an Edinburgh school sports hall changing room in 2014.
The changing room contained a disused shower area which was routinely used as an additional area for the pupils to change. The shower area had originally had a row of shower heads along the back wall forming a communal shower. This wet area was separated from the rest of the shower area by a freestanding privacy wall. The width of the area between the privacy wall and the back wall with the showerheads was approximately 900mm (Figure 1).
Privacy wall construction
The privacy wall was 3.6m long by 2.1m high, it was formed of a single layer of unreinforced clay bricks laid in stretcher bond and faced all round with a terrazzo finish to the full height of the wall. The finished wall was therefore 140mm thick. Such a slender unreinforced wall did not comply with any historical (or current) design code. When the changing room was originally designed in the early 1950s there were no relevant Building Regulations in force in Edinburgh.
Collapse of privacy wall
On the morning of the incident, a group of 11 year old pupils were using the area in front of and behind the privacy wall to get changed. At least one, and probably two pupils, who were standing in the gap between the privacy wall and the back wall, decided to support themselves off the floor by bracing their backs against one wall and both feet against the other wall. It is also possible that using this technique they were trying climb up the gap between the parallel walls. The privacy wall then toppled outwards, striking and fatally injuring one of the 11 year old pupils.
Force exceeds design loads in standards
With the pupils braced against one wall and pushing with their legs against a parallel wall, the amount of force with which they can push is not limited by friction as it would have been if they were standing on the floor. Ergonomic analysis confirmed that in this position it is possible for a small number of individuals to exert a force that exceeds the horizontal design loads given in the UK National Annex to BS EN 1991-1-1, Table NA.8. This braced position also allows individuals to climb up the gap, and consequently the force can easily be applied above the 1.2m max height given in BS EN 1991-1-1 paragraph 6.4(1).
Ergonomic analysis confirmed that in this position it is possible for a small number of individuals to exert a force that exceeds the horizontal design loads given in the UK National Annex to BS EN 1991-1-1, Table NA.8
It is felt that such wall climbing is more likely to occur in facilities used for sports/recreation and in facilities used by young people (e.g. schools, colleges, student accommodation).
Practitioners undertaking surveys should carefully assess the stability of any freestanding walls; whether they are internal or external and irrespective of whether they show any signs of distress.
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Expert Panel Comments
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There have been numerous cases of freestanding wall collapses causing fatalities, particularly to young persons. The risk was highlighted in a Standing Committee on Structural Safety (SCOSS) Alert: Preventing the collapse of freestanding walls - September 2014. You can search for safety information on freestanding walls on the CROSS website.
Horizontal loading applied by people exerting pressure has been observed previously. In the 1970s, tests were carried out at Liverpool FC on barriers in the Kop end which was then for standing only. It was found that the highest loads were applied when, to resist pressure from the crowd behind, supporters put their feet on the rail and pushed back. Had they not done so the pressure could have crushed their chests. This data was used when recommending barrier loading in the original Guide to Safety at Sports Grounds.
It is important that the designer/assessor of walls such as those in the report consider what reasonably foreseeable loads could be applied beyond the code minimum values. Additional loading may arise due to the location, type of use or thoughtless or potentially malicious actions. When reviewing risks for any structure, what would be the potential consequences of failure?
It is important that the designer/assessor of walls such as those in the report consider what reasonably foreseeable loads could be applied beyond the code minimum values.