Industry Intel

What is RAAC Concrete?

George Garrett

Senior Consultant | Development & Regeneration

Sep 04, 2023

RAAC is an acronym for:

  • Reinforced – it contains steel rebar
  • Autoclaved – it is cured under heat and pressure
  • Aerated – it is porous with air bubbles
  • Concrete – It is made of concrete

The material was very popular from the 50s until the 90s as it was cheap, ecofriendly, and durable. It fell out of use owing to concerns about how well the material stood up to the elements over time.

In the UK it was primarily used in flat roof buildings like schools and hospitals.

The problems

The aerated nature of the material means it is easy for water to get inside the material where it can accumulate. Anyone who has owned a classic car knows what happens when steel is exposed to water for long periods of time, you get rust.

This mean RAAC rots away from the inside before failing, often without warning, despite appearing completely solid from the outside.

Obviously, this make it very difficult for untrained individuals to report potential structure faults until it is too late.

Why is it in the news?

It has come to light that a lot of the schools built using RAAC have been improperly monitored, despite the buildings exceeding their intended lifespan, and now there have been cases of ceiling collapsing as the internal rot progressed in the RAAC.

This led to a nationwide survey of school buildings which, despite not being complete, has revealed enough to concern the Government.

Some of the school buildings were deteriorated to the point they were no longer safe and had to be closed, however it is worth mentioning that this is a very small number of cases so far.

However, all disruption to education is very negative.

The solutions

You can replace the roofs, but the problem will keep coming back unless you reengineer the buildings to use a different material. RAAC is inherently very lightweight making it hard to find suitable replacement as the building likely won’t be designed to support a heavier load.

The best solution would be to redevelop the sites and build brand new schools in their place, but this will take years and years and cost Billions.

There was a plan to build 700 schools in England to replace a lot of the aging stock, however this was scrapped in 2010 with the introduction of the austerity programme masterminded by George Osborne.

What we're seeing most often as a result of RAAC deterioration, is schools and other buildings identified with RAAC being labelled as potentially dangerous, and closed with little to no notice.

In summary, this problem won’t go away overnight, and will require significant capital investment to overcome. But perhaps it's best to look at it as an opportunity to do something we should have done 13 years ago – build new schools for the future...

What do you think? Feel free to reach out to me to discuss this further, any insights are useful.

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Senior Consultant | Development & Regeneration

George Garrett

George cuts through the noise to understand exactly the scope of what an organisation is looking to achieve and where a candidate can fit in that. You know with George that you won’t be getting fluffy, insubstantial waffle. Just exactly the facts.

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