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CROSS Safety Report

Fixings to steelwork

Report ID: 44 Published: 1 November 2006 Region: CROSS-UK

This report is over 2 years old

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The use of proprietary self tapping screws to fix to materials thicker than 10-12mm is questioned by a reporter.

Key Learning Outcomes

For civil and structural design engineers:

  • Connections can often be the weak link in structures and attention to detail is required

  • Careful consideration is required for fixings, particularly at interfaces between different materials. The role of tolerances should not be overlooked.

For construction professionals:

  • Quality control and competent supervision on site can ensure the correct fixings are installed in accordance with the design

  • Fixings should be installed in accordance with the manufacturer’s specifications and requirements

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.


The use of proprietary self tapping screws to fix to materials thicker than 10-12mm is questioned by a reporter. For example, fixing ties to structural steelwork. The manufacturer’s instructions normally give the maximum thickness of material on which these should be used. They believe that this recommendation is often ignored and is concerned that inappropriate use could lead to screws being weakened or sheared in torsion.

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 continuing theme is that manufacturer’s instructions must be followed for all proprietary components and it is known that fixings can and do fail where this is not followed. There are two issues:

  1. Designers may be specifying inappropriate systems or not giving sufficient information

  2. Installers may not be following the requisite instructions

Both are serious and have the potential to lead to structural failures.

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