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CROSS Safety Report

Retaining wall collapse

Report ID: 76 Published: 1 April 2007 Region: CROSS-UK

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A retaining wall is reported to have collapsed four times during the course of its life.

Key Learning Outcomes

For civil and structural design engineers:

  • Adding to the height of cantilever walls should be carried out with care. If the additional load added is a UDL (like wind), then the bending moment at the base is proportional to the square of the height

  • Consider what reasonably foreseeable loads could be applied beyond the code minimum values on elements such as freestanding walls

  • A design check should be carried out on an existing wall or parapet that have attachments added to them

For construction professionals:

  • Alterations should not be made to masonry retaining wall without approval or an assessment being carried out by a suitably qualified engineer

Full Report

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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.


A retaining wall is reported to have collapsed four times during the course of its life says a reporter. The wall was approximately 1.7m high and built on a strip footing with steel rods (starter bars) protruding out approximately 300mm here and there.

Square mesh fabric reinforcement dropped in the cavity of the wall. There is apparently very little provision for drainage behind the wall and a fence was bolted to the top block course which may have contributed to the latest collapse which occurred during high winds.

Expert Panel Comments

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Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

A retaining wall 1.7 m high with a fence on top is a significant structure which demands proper design and construction.

References giving guidance on good practice include:  


This report has been re-published to clarify the Key Learning Outcomes regarding the design of masonry walls.

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