Skip to main content

CROSS Safety Report

Alteration of calculations on constructed loft conversion

Report ID: 580 Published: 1 July 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 says they were pressurised to adjust structural design calculations to pass a building control check.

Key Learning Outcomes

For construction professionals:

  • Any alterations to structural elements should be approved by the design engineer prior to works being carried out on site

  • It is wrong to ask a designer to adjust calculations to pass a building control check if the calculations do not reflect what was built. Calculations are a means of predicting safety; manipulating calculations to avoid scrutiny is unethical and may be dangerous.

For civil and structural design engineers:

  • If you have safety concerns about the way you have been asked to update calculations or drawings:

    1. Your first step should be to raise this with the organisations concerned if possible

    2. If applicable, you should speak to your line manager

    3. If this does not resolve the issue, or if the response you receive is inadequate, then you should inform the appropriate regulator

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.


A reporter says they were pressurised to retrospectively change calculations and drawings following the completion of works at a domestic property. This was to reflect alterations made by the builders contrary to the architect’s original drawings and the structural engineer’s stipulations.

The original position of a beam was changed on site which resulted in it not passing deflection checks, so they were forced to adjust the calculations to pass building control. This, they say, is a breach of both the regulations and the structural engineer’s code of practice. It may also constitute a case of fraud against the client. This was not an isolated case as, according to them, it took place in other cases.

Expert Panel Comments

Find out more about the Expert Panels

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.

This illustrates a wider theme that emerges from many reports which is to observe that what is built is not necessarily what is shown on the original drawings. It is not unusual for changes to be made to suit site conditions. For that reason, many contracts include an obligation to produce ‘as built records’.

However, all such changes should be sanctioned in advance and those sanctioning them must verify the change will not violate design intent. Calculations are a means of predicting safety; manipulating calculations to avoid scrutiny is unscrupulous and may be dangerous. The reporter says that they were ‘forced’ to change the calculations but does not say by whom, and apparently felt unable to challenge the situation.

Calculations are a means of predicting safety; manipulating calculations to avoid scrutiny is unscrupulous and may be dangerous

Reporting a concern

It is not uncommon for there to be robust discussions within design organisations about calculations or details but all those involved in the production and checking must follow design requirements without being put under pressure to cut corners. If a designer has concerns about the way they have been asked to proceed, they should raise these concerns with a senior person in the organisation. Should concerns remain then, if building regulations are involved, the relevant local authority may be informed although there may be a risk of not maintaining confidentiality.

The Health and Safety Executive (HSE) could also be informed if the risk of failure is particularly severe. For cases of conduct which may breach Institution rules, confidential reports may be made to institution disciplinary panels.

A report can also be made to CROSS and advice may be given but we have no powers to act and CROSS is not a whistleblowing site. There is however a government website on whistleblowing for employees which gives the legal position for those who wish to disclose wrongdoing in the public interest.

Submit a report

Your report will make a difference. It will help to create positive change and improve safety.

Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others.