Reinforced Autoclaved Aerated Concrete – a headline grabber or a realistic claims risk?

Reinforced Autoclaved Aerated Concrete (“RAAC”) has hit the press recently after more than 100 schools were fully or partially closed on the eve of the new term due to the risks created by its presence. In this article we discuss potential risks for the construction sector and its insurers.

What is RAAC?

RAAC is a form of concrete which was first developed in Sweden in the 1920s. It became popular for building construction in the UK following the second world war due to its lighter weight and lower cost (relative to traditional concrete). RAAC panels and planks are commonly found in flat roofs, floors and walls. Its usage in the UK ceased in the mid-1990s after concerns arose about its limited structural integrity, particularly when used in roofing. 

RAAC was used in a wide range of building types but is believed to be most commonly found in schools, hospitals and other public buildings.

Why is it a problem?

In May 2019, the Standing Committee on Structural Safety (“SCOSS”) published an alert in response to the sudden collapse of a school roof which contained RAAC. It noted that the useful life of RAAC roof planks has been estimated to be around 30 years, which means that almost all planks have either exceeded or are close to exceeding their expected service life. SCOSS warned that buildings where RAAC roof planks are present are at risk (albeit to an uncertain extent) of collapse and possibly injury.

The SCOSS alert advises building owners and managers to:

  1. Identify whether RAAC installations are present in buildings
  2. Appoint an appropriately experienced Chartered Structural Engineer or Chartered Building Surveyor to carry out risk assessments
  3. Consider remediation or replacement, as appropriate

The Institute of Structural Engineers maintains that, when properly designed, manufactured, and maintained, RAAC installations are considered safe. However, because RAAC is adversely affected by moisture and variations in temperature and roof panels containing RAAC can creep and deflect over time, cracking and spalling can develop. In extreme examples (such as where there is insufficient bearing and structural integrity has been compromised) panels can fracture or collapse entirely.

The risk of RAAC-related claims

Usage of RAAC in construction in the UK ceased in the mid-1990s, which means that any contractual and tortious claims against those involved in the design and construction of buildings containing RAAC panels and planks (against the likes of architects, engineers and contractors) will be time-barred. 

The extension to the limitation period under section 1 of the Defective Premises Act 1972 to 30 years may give any person with an interest in a dwelling affected by RAAC the right to bring a claim. However, those claiming are likely to face a challenge to prove that RAAC was not a “proper material” or that the dwelling was unfit for habitation at the time construction was completed. To the extent there is a problem, it is because the material has come to the end of its natural design life. Claimants may argue that the problem arises due to improper maintenance but that does not give a right of action under the Defective Premises Act. 

It might be arguable that the presence of RAAC could represent a “relevant defect” under section 120 of the Building Safety Act, if it can be established that its use causes a building safety risk. This may give rise to applications being made for Remediation Order or Remediation Contribution Orders under sections 123 or 124 of the Building Safety Act. Such applications are made against landlords and developers as opposed to construction professionals.

Perhaps a more realistic claims risk arises from advice given by professionals in the construction section in relation to RAAC affected buildings towards the end of their lifecycle. Examples of potential claims may be where a building surveyor has been appointed to report on the condition of a building for a prospective purchaser. Alternatively, a risk could arise for any surveyors engaged to manage a building or wider property portfolio. In either case, if those surveyors have failed to act with reasonable skill and care in overlooking the existence of RAAC, or have failed to follow the SCOSS guidance in how to deal with it, that could give rise to a claim risk. The effect of such an omission may be that there is an adverse impact on the value of the property and in the worst case, the panels could collapse which a claimant may argue could have been avoided with proper advice.

Mitigating the risk of claims

We identify some key considerations for mitigating the risk of professional indemnity claims:

  • When reporting on the condition of a building for a prospective purchaser or managing a property, thorough inspections and risk assessments should be undertaken to identify the presence of RAAC in roof panels, wall panels and floor panels. 
  • When assessing or surveying buildings which were constructed between 1950 and 1995, surveyors, architects, engineers and property managers should be alerted to the use of RACC in roofs and floors.
  • Where RAAC has been identified, the property owner or prospective purchaser should be informed promptly of its presence and the SCOSS guidance should be followed.
  • Surveyors may wish to add reference to RAAC in precedent documents to “force” colleagues to consider it as part of their assessment of buildings, rather than to leave its identification to chance. 
  • Internal refresher training sessions focussed on the SCOSS guidance could or should be undertaken.

Underwriters may wish to ask questions of policyholders about work undertaken particularly in connection with public sector property. Underwriters should be aware that while the use of RAAC was most prevalent in public buildings, it can still affect surveyors operating in private industry because, for example, a former public building may be converted e.g. from public to private. Increased used of retroactive dates may be appropriate to protect against claims arising from historic breaches.


When an issue of this nature hits the national press, it can prompt building owners to undertake additional reviews of their estates. If they suffer losses, either because they are likely to have to incur costs remedying the problems RAAC can cause or because their estate is worth less as a result, they may well assess whether anyone might be responsible. Claims relating to RAAC will generally be challenging but there are certain factual situations which increase the risk for insurers, with particular professions more exposed than others. 

Our content explained

Every piece of content we create is correct on the date it’s published but please don’t rely on it as legal advice. If you’d like to speak to us about your own legal requirements, please contact one of our expert lawyers.

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