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CROSS Safety Report

Retaining wall concerns and the stance of a local authority

Report ID: 189 Published: 1 July 2010 Region: CROSS-UK

This report is over 2 years old

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A reporter was asked by a client to assess a retaining wall built on their boundary by a neighbour who had erected a new dwelling. A review of the calculations and a typical section gave serious concern for its strength.

Key Learning Outcomes

For homeowners and builders:

  • Be aware that retaining wall design should be carried out by a suitably qualified and experienced engineer

For all built environment professionals:

  • If you are aware of a live or urgent safety issue:

    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

This section contains the Full Report submitted to CROSS and describes the reporter’s concerns or experiences. However, the text has been edited for clarity, and identifiable details have been removed to ensure anonymity and confidentiality. 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 was asked by a client to assess a retaining wall built on their boundary by a neighbour who had erected a new dwelling. Of reinforced concrete block work construction, the wall is about 2.75m high at its highest point and retained the client’s land. On the other side of the wall is an access road to the neighbour’s new dwelling. From a visual inspection the wall appeared sound.

Design calculations

However, a review of the calculations and a typical section, gave serious concern for its strength. From the layout of the calculations, it was reasonably obvious that they could not apply to the structure in question. The reporter contacted the Engineer named on the calculations to ask them if they could deal with the Section 167 issues.

It was then established that the engineer had not designed the retaining wall or overseen its construction. They did not know that his calculations had been put into an Agreement for the Works. The calculations were for a garage wall with concrete floor over (to support part of the new dwelling) and part ground retaining.

Understrength retaining wall

The reporter’s firm then informed their client that the retaining wall was substantially under strength, and therefore an unsafe structure requiring action to make it safe as soon as possible. The firm took the view that they had done their duty in so far as they had advised of a severe health and safety risk and recommended a course of rectification. However, they believed that they should also inform the relevant authority and consequently wrote to the local authority.

They suggested that an engineer’s calculations had been fraudulently used and issued, giving cause for concern as to the integrity of the construction as a whole. The firm’s recommendation was that the local authority takes action under Section 77 of the Building Act. The local authorities reply was, paraphrased: --our officer has visited the site and upon inspection there was no visible change in the walls condition (from a previous visit) and therefore we are taking no action at this time.

They ask, through CROSS, what more can the firm do about this clear and present danger?

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.

It is very difficult when professional advice on safety is not taken up and there have been, as previously reported, a number of recent collapses of boundary walls and retaining walls sometimes with fatal results and the matter is important. Boundary walls may however not come within the jurisdiction of building control unless they are deemed to be dangerous structures, and this is the subject of the following comment published on the CROSS website.

 ‘Report 166 concerning the collapse of a freestanding boundary wall misses the main problem with these walls, which is that they are not covered by building regulations (unless they form part of a building), so their construction is unregulated. Therefore, local authority building control officers have no authority to do anything about the design or condition of such a wall unless someone reports it as a dangerous structure (by which time it is usually too late).’

A further step can be taken by explaining again these concerns in writing (possibly in a registered letter) to the head of building control with copies to the Highways Agency and the Health and Safety Executive (HSE).  The local authority has powers under the Building Act to take action and below is a paragraph taken from a typical council web site:

Local Authorities are given discretionary powers to deal with Dangerous Structures by Sections 77 and 78 of the Building Act 1984.

The Council will take action where deemed appropriate to ensure public safety, either to require the owner to make the structure safe, or in an emergency, to take action then recover costs from the owner.  Emergency action might be to remove the danger, perhaps by demolition or partial demolition, or to provide barriers around the dangerous structure.


If there is still no satisfactory response then as a citizen, the reporter can complain about the action, or inaction, of a local authority to the Local Authority Ombudsman who has powers to investigate. Mention made in the letter to the local authority that recourse might be made to the Ombudsman could have a salutary effect.

It should be noted that the authority can only take legal action when the building or structure is in such a condition as to be dangerous, they cannot take action on the basis that the structure is likely to become dangerous in the future. If the authority shares the concern of the engineer they could write to the owner of the wall advising them of the authority’s concern and advising that if the condition of the wall deteriorates the authority may instigate proceedings against them as owners’

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