Reinforced Autoclaved Aerated Concrete (RAAC) was commonly used in buildings between the 1950s and 1980s, but it has since been discovered it can be susceptible to structural problems, such as cracking and bowing.
Following the sudden collapse of a school flat roof in 2018, a specialist study group was set up to research RAAC and advise the construction industry. It is recommended that building owners and managers carry out RAAC surveys of their buildings to identify the presence of RAAC and assess its condition.
The Bureau Veritas Construction Consultancy team is working with clients to complete RAAC surveys with confidence, giving the insights needed to shape their next steps and ensure building safety.
What is RAAC?
Reinforced Autoclaved Aerated Concrete, or RAAC, is a lightweight cement-based material that was used in construction from the 1950s, more extensively in the 1960s and 1970s, and through to the 1980s. It is aerated, has no course aggregate, is lightweight, highly permeable and of low strength. It also behaves very differently from traditional reinforced concrete.
The material is generally found in planks used in floors and flat roofs. The most critical areas that cause problems include the supports by the wall at each end of RAAC planks.
RAAC reinforcement consists of steel bars extending the length of the planks, that are locked in place by a series of perpendicular, transverse bars. However, variations in manufacturing quality meant the transverse reinforcing bars - which are crucial for a roof’s structural integrity - were sometimes positioned away from the bearing area at the ends of the planks. This can leave the inherently weak aerated concrete to take all the load.
What does a Bureau Veritas RAAC survey include?
There are two main types of RAAC survey:
- Detection surveys: To identify the presence of RAAC in a building. This is typically non-intrusive and involves a visual inspection of the building. It is carried out by a Level 1 or Level 2 inspector.
- Condition surveys: If RAAC has been identified in a building, this will assess the condition of the RAAC. It may involve non-destructive testing and may also require the surveyor to take samples of the RAAC for analysis. It is completed by a Level 3 qualified Structural Engineer, who will complete a review the building and carry out a risk analysis. This will be followed by a report with recommendations on how to manage any risks.
RAAC surveys are important for building owners and managers because they can help to identify and manage the risk of structural failure. RAAC surveys are particularly important for buildings that are used by the public, such as schools and hospitals.
What are the benefits of an RAAC survey?
- Identify the presence of RAAC in your building
- Assess the condition of RAAC
- Identify any potential risks of structural failure
- Get recommendations on how to manage the risk of structural failure
- Protect the safety of your building's occupants and users
Why choose Bureau Veritas for RAAC surveys?
We’re experts in building safety, offering a wide range of services that mitigate risk, improve quality and enhance safety at every stage of the building life cycle.
- An end-to-end, independent, multi-disciplinary partner
- Rapid, comprehensive reports using our MAIA online platform
- No affiliation to remediation companies for completely impartial consultancy
- A global leader in testing, inspection, and certification (TIC), offering additional support across safety, compliance, certification, sustainability and more