IOSH issues statement on RAAC

26 September 2023

REINFORCED AUTOCLAVED aerated concrete (RAAC) poses a very serious safety risk to people using buildings which contain it because of the potential for it to collapse.

So, it’s crucial that those responsible for buildings identify whether it is present, assess the risk, and have a robust plan in place to manage and control the risks and prevent any possible failure and collapse.

RAAC is a building material that is a lightweight form of concrete which is usually found in precast roof panels and planks, and in floors and walls.

It was commonly used in construction in the UK and some other countries between the 1960s and mid-1990s, meaning any building which was built or modified in this period may contain it.

Research has shown that RAAC is much less robust than traditional concrete. Its condition deteriorates further if it gets wet, for example leaks in roofs, as this can compromise the reinforcement bars contained within RAAC planks. A failure caused by this could lead to collapse – and have significant safety consequences.

Anyone responsible for buildings should know if RAAC is present. If they don’t, they should seek to find out as soon as possible. If it is present, there should be an assessment to understand the risks and there should be a management plan, detailing how the risk is being managed and controlled in the short term and long term. This should be done in collaboration with a competent structural engineer.

The management plan should include regular inspection, again by competent professionals, to help identify if there are any issues with RAAC at an early stage.

More information can be gained from the website of the Institution of Structural Engineers.