Have you heard about some schools around the UK being closed due to the unknown condition of RAAC? Unfortunately, it is not just schools which are at risk. Find out what you need to know below.
In this article we will cover:
What is RAAC?
Where is RAAC used?
What is the issue with RAAC?
What is being done?
What happens if you discover RAAC?
Reinforced Autoclaved Aerated Concrete (RAAC), which is now being dubbed “crumble-prone concrete”, is the culprit behind the nationwide school closures mentioned in the news recently.
In 2019, it came to the attention of the Standing Committee on Structural Safety (SCSS) that RAAC posed a significant risk of failure, meaning it could deteriorate and collapse.
In 2022, the Office of Government Property sent a Safety Briefing Notice to property leaders reiterating this concern, stating “RAAC is now life-expired and liable to collapse.”
The serious safety implications of this realisation have caused schools to temporarily shut across the country, as RAAC was a fairly common building materials used throughout the 50s, 60s and 70s in both public and private buildings.
Currently, close to 150 schools have closed due to the “crumbling concrete crisis”, but the issue also affects an unknown number of hospitals, courts, private sector offices and warehouses, and residential buildings.
This article offers expert advice on the topic, covering everything you need to know to stay safe and protect your property, including how to fix the issue if it affects you.
What is RAAC?
RAAC is a relatively lightweight and strong form of aerated concrete containing a mesh of reinforcing steel wires. It’s also cured in an autoclave, which is high-heat, high-pressure steam chamber.
Being relatively cheap, lighter than traditional concrete and a good thermal insulator, RAAC can sometimes be a good material to use, and it is still used in construction projects throughout the world.
However, it’s only a suitable material if properly designed, manufactured, installed and maintained.
Experts are now realising the batches built and used in the UK in the 50s, 60s, 70s and 80s aren’t as durable as initially thought, and the material is now being called “crumbly and prone to collapse.”
Reportedly, RAAC used in roofs is most likely to see the worst deterioration, as water is a main driver.
This is obviously a huge national concern, although no buildings have collapsed as of yet. Efforts are now focused on assessing buildings and taking the appropriate action to prevent what some are calling “a cladding-style scandal in the making” – referring to the tragic events at Grenfell Tower in 2017.
Where is RAAC used?
RAAC has been commonly used extensively across the UK and Globally, with use of it first being used in the 1950's. It was widely used in construction and can be found in homes, schools, hospitals and any other building.
This will come as a concern to landlords, who have a legal responsibility to provide a safe living environment for their tenants.
What is the actual issue with using RAAC?
Most concrete products used coarse aggregates, such as crushed stone and gravel which add strength to concrete. RAAC does not use coarse aggregates, and essentially crumbles over time, often made worse by getting wet.
At the time it was a cheaper, lighter form of concrete, however this approach has not worked, and we are not seeing failures in the product.
There doesn't appear to be any immediate danger, relevant experts are warning of likely problems in the near future, and that immediate action must be taken to prevent future accidents.
What is being done?
The NHS, which has seven buildings primarily constructed from RAAC, has issued instructions requiring the removal of the unsafe material by 2030.
As seen on the news, schools are closing in response to the Department of Education’s instructions for all school buildings to be checked for RAAC, adding that they’ll offer financial support for expert guidance to be brought in.
Landlords are responsible for arranging building surveys on their properties, so if you suspect RAAC was used in any of your owned homes, or you own a council house constructed between the 50s and 80s, it might be worth speaking to a building surveyor.
What happens if you discover RAAC?
A trained person will come and look at the important supporting part (called an “end bearing”). If that part isn’t the right size (75mm), they’ll need to take a closer look.
They might use a special tool or even a drill to poke around and find out how deep the supporting part goes into the material (RAAC) and where some extra strength (transverse reinforcement) is added.
If that extra strength is in the right place and the supporting part is within the size recommended by the people who made it (40mm-50mm), then everything should work just fine. If not, they’ll need to add extra supports and maybe do some other fixes to make sure it’s safe and works properly.
If you, or your business need Safety, HR or Accreditation support, please get in touch and a member of the team will be in touch.