CROSS Safety Report
Substitution of cold rolled hollow sections for hot rolled hollow sections
This report is over 2 years old
A reporter was advised by two of their manufacturers that their buyers have purchased cold formed hollow sections rather than the hot formed hollow section which we clearly identified in our calculations.
Key Learning Outcomes
For construction professionals:
Substitution of construction elements, for a lower grade material, should not be made without design team verification
Talk to the design team and regularly discuss your use of products, components, and materials
Consider introducing a quality assurance process that covers the correct use of products, components, and materials on site
Share your knowledge of the behaviour of products, components, and materials
Routinely raise the risks associated with substitutions to contractors and the wider project team
If you are concerned that the correct material grade may not have been installed on site, consider asking the contractor for the material certificates
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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.
We, says another reporter, carry out the structural design work for a number of modular building manufacturers. Very recently we have been advised by two of them that their buyers have purchased cold formed hollow sections rather than the hot formed hollow section which we clearly identified in our calculations.
They have done this because cold formed sections are cheaper although of a lower specification. We are concerned that buyers of structural materials sometimes seem to be cost driven and do not appreciate the importance of the steel grade.
Whilst we have become aware of at least two instances where this has happened and have been able to take steps to remedy it, there may be others where there are buildings with structurally inadequate members.
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It is worth noting that an alteration to the design (including specification) by 'another' person should be considered under Regulation 11 (ss 3 & 4) of the Construction (Design and Management) Regulations 2007 whereby the Buyer takes on the duties of the 'Designer' and should consider the risks to health and safety (in the construction process and use (of the structure)) that may arise from the alteration to the original specification.
Investigation, should a failure occur, could identify the reason for the failure and at what stage the change in the original specification took place and who was responsible for making that change.
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This is not the first time that CROSS has become aware of unauthorised changes being made without the knowledge of the designers. The unauthorised use of non-structural steel box sections and changes to structural fixings are two more examples. It is difficult for the designer to prevent others from effecting changes other than by making it clear, on drawings, or in accompanying issue slips, that all changes are to be referred to the designer.
Those responsible for value engineering also need to ensure that their decisions do not affect the original design criteria. Concerns of this type need to be brought to the attention of buyers and quantity surveyors. Designers need to remain vigilant to ensure that the materials they specify are used on site.