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CROSS Safety Report

Roof constructed without structural input

Report ID: 515 Published: 1 January 2016 Region: CROSS-UK

This report is over 2 years old

Please be aware that it might contain information that is no longer up to date. We keep all reports available for historic reference and as learning aids.


A reporter wants to highlight the problem of builders working off plans provided by an architect or surveyor and assuming that section sizes shown on their drawings are structurally adequate.

Key Learning Outcomes

For domestic clients:

  • It is good practice to have a competent suitably qualified engineer carry out design checks / calculations and provide guidance for any structural works required

  • There is always a risk that safety will be compromised when the lowest cost is the main criteria for selecting products, processes or people

For all built environment professionals:

  • It is important to recognise and know the boundaries of your expertise and work within the limits of your competence

  • Health and Safety legislation places duties on individuals as well as companies to ensure that they do not put people at risk of harm

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.


At the bid stage for a project, a reporter, whose firm had been instructed by a client to carry out building control calculations for a project, had discussed with the builder concerns about the scheme for the roof as drawn by the architect.

After appointment, they arranged to visit site to inspect the existing structure but found that the work had already started. During the visit, several concerns were noted and passed on to the contractor and the client. The following day, the client decided to end the involvement of the engineers and stated that they would proceed with the builder and architect alone to resolve the issues.

The engineers then emailed the client summarising their concerns about the way in which the complicated roof had been built. They concluded that the structure was potentially unsafe and that, in their opinion, no work should continue without further investigation.

The reporter wants to highlight the problem of builders working off plans provided by an architect or surveyor and assuming that section sizes shown on their drawings are structurally adequate. This is the worst case the reporter has encountered, but the general problem is not uncommon.

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.

There is no requirement in building regulations for calculations to be submitted by a competent engineer and domestic clients are often not well enough informed as to what is the role of the engineer. It illustrates the nature of the construction industry at the small, usually domestic, end of the market. The Institution of Structural Engineers (IStructE) is currently working on guidance for domestic clients on the importance of appointing a structural engineer.

The Construction Industry Research and Information Association (CIRIA) is also working on new guidance for alteration work to small building projects. In any event, builders on projects of all sizes have responsibilities under CDM Regulations 2015 (CDM 2015) to plan, manage and monitor all work carried out by themselves and their workers. It is possible that an architect is in breach of a duty of care, and CDM 2015 by not insisting on the involvement of an engineer where that is necessary. Until the process is tightened, incidents such as these will continue.

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