The UK is facing growing concerns over the risks associated with the use of Reinforced Autoclaved Aerated Concrete (RAAC) in buildings, following previous cases of material failure in a number of operational schools. In September 2023, the Department for Education released a guidance note on the identification of the presence of Reinforced Autoclaved Aerated Concrete in buildings. This document can be found by accessing the link as follows: Reinforced autoclaved aerated concrete: identification guidance – GOV.UK (www.gov.uk).
Reinforced Autoclaved Aerated Concrete (RAAC) is lightweight, ‘bubbly’ form of concrete commonly used in construction between the 1950s and mid-1990s. It is predominantly found as precast panels in roofs, walls and floors.
How can I identify Reinforced Autoclaved Aerated Concrete (RAAC)?
If the concrete is exposed and is not obstructed by surface coverings, there are a number of common signs which indicate that a building material may be of Reinforced Autoclaved Aerated Concrete, such as:
- The building uses pre-cast concrete panels, which typically have 600MM laps.
- The roof, floor or walls will appear to be light-grey or white in colour, which is a common feature of concrete panels.
- RAAC panels commonly have v – shaped grooves at regular 600mm spacings where they join together.
- RAAC panels are soft, to such extent that an indentation can be made to the surface of the material by pressing into it with a sharp object, such as a pen.
What are the risks associated with the use of Reinforced Autoclaved Aerated Concrete (RAAC)?
In the 1990s, there had been other concerns raised relating to structural deficiencies in RAAC by both the Building Research Establishment and SCOSS. It was established that RAAC concrete has a poor service life and is prone to cracking and displacement. This is due to the aerated nature of the RAAC materials, which make the material vulnerable to moisture ingress. As the material continues to absorb moisture, the reinforcement steels will begin to rust and will cause concrete displacement, which can result in structural failure if not rectified.
What can I do if my building has Reinforced Autoclaved Aerated Concrete (RAAC)
If the building structure is not covered, a visual inspection can be undertaken to identify whether the building is constructed of RAAC materials. These are explained in the section above – How can I identify Reinforced Autoclaved Aerated Concrete (RAAC)?
Based on a visual inspection, if you are certain that the building may contain RAAC materials or unsure whether this is the case, the next stage in identification and management of the RAAC materials will be to appoint a Chartered Building Surveyor or a Structural Engineer.
If you believe that your property may be constructed of Reinforced Autoclaved Aerated Concrete (RAAC), then please do not hesitate to contact us. We can provide you with the full range of services, from undertaking a Level 3 Building Survey to identify the presence of RAAC in the building to Project Manage any remedial works required, so please do not hesitate to contact us.
