RAAC: The UK’s crumbling concrete crisis
By now, most people in the UK have heard about RAAC and the dangers it poses. The seriousness of the problem hit home when 100 schools were ordered to shut down their buildings just days before the start of the 2023 academic year.
What is RAAC?
Reinforced Autoclaved Aerated Concrete is commonly known as RAAC. It is a lightweight, aerated construction material that resembles concrete but is weaker and degrades faster than concrete.
Between the 1950s and 1990s, the construction industry mainly used it to build flat roofs. On occasion, builders also used it for floors and walls. This cheaper alternative to concrete is easier to make and use. However, it is less durable and has a lifespan of approximately 30 years.
RAAC consists of two parts – aerated autoclaved concrete, made with aluminium added to a lime or cement-based concrete mix, and a steel reinforcement. This mixture reacts and forms countless tiny bubbles, making up the bulk of the material. It is widely used as precast panels.
Structurally, the material is not as strong as concrete because the air pockets take on moisture that spreads throughout the material and also affects any coatings such as the bitumen used on roofing panels. Additionally, it exposes rebars to decay and rust, weakening them and harming overall structural integrity.
The HSE warned that RAAC has reached the end of its lifespan and can collapse with little or no notice. It called on all building owners and other responsible persons to first assess if RAAC is present in a building and then take the needed measures to manage risks.
The RAAC crisis
When one thinks of all the buildings in the UK that used RAAC in their construction, it is a matter of great concern. This building material can likely be found in schools, hospitals, community centres, shopping centres, and office blocks – all of which have thousands of people moving through them on a daily basis.
The UK Government published the number of state-funded schools, nursery schools, and further education facilities in England faced by the RAAC crisis. As of 30 August 2023, there were approximately 156 buildings with the material. RAAC was even spotted in the parliament building.
Of these buildings, only 56 have measures in place to counter the risks associated with RAAC. After the roof of the Singlewell Primary School in Kent collapsed, the Kent Council issued a warning to other local authorities.
Construction experts view RAAC as a ticking time bomb. They estimate that roughly half of the four million non-domestic buildings in the UK are at risk.
What can you do to address RAAC in your buildings?
The HSE recommends a systematic approach of identify, assess, and manage. If you either confirm or suspect the presence of RAAC slabs or other RAAC constructions in your buildings, you should employ the services of a structural engineer.
Sections 5 and 6 of the Reinforced Autoclaved Aerated Concrete (RAAC) Investigation and Assessment – Further Guidance from the Institution of Structural Engineers explain how to manage RAAC risks. You can also use the HSE’s guidance on managing risks and risk assessments at work.
To demarcate areas and warn people of the presence of RAAC, Seton’s RAAC safety signage is a must for your building. These eye-catching RAAC signs keep people out of dangerous locations and help you to complete the necessary structural maintenance.
You can even combine these with our rugged barriers and other safety signage, such as the PPE required for construction. The RAAC issue affects many buildings and a simple sign can boost safety and save lives.