RAAC Plank Structural Surveys

The Structural Engineering team at Frankham specialises in assessing the risk of failure from defective Reinforced Autoclaved Aerated Concrete (RAAC) roof planks for building owners, including Hospital Trusts, Local Councils, and government premises through their FM contractors.

We address concerns with RAAC construction, which were first highlighted after a collapse of RAAC roof planks at a school in Kent. The Standing Committee on Structural Safety (SCOSS) raised a safety alert in 2019 and, now operating under the name Collaborative Reporting for Safer Structures (CROSS), continues to raise awareness on RAAC structural safety. Building Research Establishment (BRE) Information Paper IP10/96 also highlights concerns with RAAC roof planks and advises that they should be inspected by a Structural Engineer and appropriate measures taken to remediate defects and advise on long-term inspection regimes.

At Frankham, we understand the importance of minimal disruption during investigations and our team of experts will work closely with you to ensure the safe use of your assets.


Get in touch:

Contact our Structural Engineering team for a review of your building’s safety risks in relation to RAAC.


About Reinforced Autoclaved Aerated Concrete (RAAC)

What is RAAC?

RAAC is a lightweight and porous type of concrete and was commonly used in the construction of buildings including schools, hospitals, hotels, theatres, housing and any kind of public or private sector building developed or extended to from the 1950s to the mid-1990s

RAAC panels are most commonly discovered on flat roofs, but they can also be located in pitched roofs, floors, or walls.

Identifying RAAC panels

RAAC panels have distinct characteristics and can be easily identified if a building structure is not covered by finishes or decor, such as ceilings. However, it’s essential to exercise caution: if your inspection requires accessing areas behind ceilings or finishes, please consult guidance on managing asbestos and the building’s asbestos register beforehand. Care should also be taken not to damage the panels when removing finishes.

RAAC panels can be light-grey or white in appearance, with the underside of the panels appearing smooth. The inside of the planks will appear bubbly and, unlike traditional concrete, will not contain visible stones (aggregate) in the panels.

When looking directly at the structure, RAAC may be present if you can see one or more of the following:

  • 600mm wide concrete panels (typically)
  • Distinctive V-shaped grooves at regularly spacing (normally 600mm in a floor, wall or ceiling)
  • Floors, walls or ceilings that are white or light-grey (where they have not been painted)
  • Drawings of your buildings that refer to RAAC or mention any of the following manufacturers Siporex, Durox, Celcon, Hebel and Ytong

Managing the Outcome

Comprehensive Reporting

We will provide you with a detailed report that identifies the presence of Reinforced Autoclaved Aerated Concrete (RAAC) within your building. This report not only confirms the existence of RAAC but also identifies specific locations and assesses the level of risk, all in accordance with the standards set by IStructE and other relevant guidance.

Expert Advice on Temporary Measures

When the risk assessment indicates an immediate need for action, our team can provide assistance in designing temporary measures. We can also guide you through the administrative process and help you appoint qualified contractors. These temporary solutions may permit the continued use of your property while we work on finalising permanent measures designed by our team.

Design and Specification of Strengthening or Replacement Structure

Every building with RAAC issues is unique and will have its own individual challenges. Therefore, a standard single fix cannot be defined for all the situations we encounter. From our detailed investigations and design, we will provide you with the best solution.

Additional Services

In addition to structural solutions, we can assist in the procurement and management of suitable contractors. We can also provide details into new or replacement finishes, manage the diversion of electrical services and handle asbestos management. Each service is carried out by one of our specialist disciplines.

How you can appoint us

Our experts have been working with building owners, including Schools, Hospital Trusts, Local Councils, Commercial Properties and Government Premises alongside their FM contractors, to assess the safety of RAAC construction.

The Building Research Establishment (BRE) Information Paper IP10/96 highlights the concerns with RAAC roof planks and advises that they should be inspected and assessed by a Structural Engineer. That’s where we come in. At Frankham, our Structural Engineers understand how sensitive these surveys can be, and we always plan our investigations with minimal disruption to normal activities. Our Engineers produce surveys and reports that align with the new guidance and will categorise your risk with coherent advice on the need for remediation or other action.

Our experts will liaise with you directly and arrange to visit your sites, undertaking carefully planned investigations to determine the structural safety risk and advise on any remedial actions required at every step.

You can trust our expertise to ensure your estates management teams have confidence in allowing safe use of their assets.

Appointing us directly through frameworks

We are on a number of local authority and social housing provider frameworks and have arrangements in place for short notice instructions to undertake our services.

  • Braintree District Council  – Construction Consultancy Framework
  • Central Housing Investment Consortium – Consultancy Services Framework 2021
  • Fusion 21 – Consultants Framework
  • London Borough of Hammersmith and Fulham – Consultancy Services Framework
  • NHS Shared Business Services – NHS SBS Healthcare Planning, Construction Consultancy and Ancillary
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"We had over 110 nationwide government buildings of various age and size that needed to be urgently assessed with respect to risk from failure of RAAC roofs. The Frankham Consultancy Group Structural Engineering team were reactive to our needs, and we were able to complete the surveys safely, issuing reports in short time all to the satisfaction of our client."

Gareth Blore, Programme Director at Mitie

Find out more and get in touch