A hidden danger: The risks of RAAC in school buildings 

News | September 5, 2023

2 min read

A recent report by the National Audit Office (NAO) highlights a critical concern involving approximately 700,000 children attending schools in England. These institutions urgently require major rebuilding or renovation, with about 38% occupying structures that have exceeded their projected design life. 

Among them are schools constructed between the 1950s and 1980s using Reinforced Autoclaved Aerated Concrete (RAAC), a material that poses imminent threats of collapse. Notably, close to 600 schools are currently undergoing immediate structural investigations relating to RAAC.

A ticking time bomb

Although visually similar to traditional concrete, RAAC exhibits significantly weaker properties, characterised by its bubble-like structure akin to chocolate Aero bars. The concealed nature of this material, typically hidden above ceilings, often renders schools unaware of its presence until faced with potential disaster.

As a report on RAAC from the Institution of Structural Engineers noted: “The nature of any warning signs of the sudden failure at the bearings is not fully known. Not all defects are visible – panels which appear to be in good condition may conceal hidden defects which could present a risk to the integrity of the panels. The corrosion of reinforcement could lead to large pieces of RAAC falling, which presents a risk to occupants.”

This is not a theoretical problem. Already, RAAC has taken casualties. In one incident at Dore Primary School in Sheffield, cladding fell off the roof, injuring a parent. In 2018, the roof partially collapsed at Singlewell Primary School in Gravesend. Thankfully, this particular incident occurred during the weekend, meaning no one was onsite. 

Urgent action is needed 

The structural concerns surrounding RAAC have prompted the Standing Committee on Structural Safety to issue a safety alert, recommending the replacement of RAAC planks installed before 1980. 

However, alarmingly, only 42% of the 14,900 schools built between 1930 and 1990 have taken measures to identify the presence of RAAC. Given the risks of injury stemming from this material, the DfE is strongly urging schools to conduct checks on their buildings as a matter of urgency.

For institutions unsure of where to start, examining original building designs or modification paperwork for terms such “reinforced autoclaved aerated concrete” or “RAAC” should be their first point of call. Mention of certain brands, such as “Siporex” and “Durox,” may also denote the presence RAAC.

Of course, this is just the first step. To remove RAAC safely while minimising disruption, seeking the assistance of chartered building surveyors is highly recommended.

How we can help

HartDixon’s RICS-qualified chartered surveyors are here to assist schools in identifying and mitigating risks related to RAAC. Our extensive experience in handling deleterious materials, combined with our expertise in school environments, enables us to grasp the intricacies of construction while minimizing disruptions to education.

Our team will work closely with your institution, conducting meticulous investigations to evaluate structural safety risks and oversee appropriate remedial actions at each stage.

Should you have concerns about the potential presence of RAAC in your school, do not hesitate to contact our dedicated team for assistance or further information. Together, we can take proactive measures to safeguard the well-being of your students, staff and teachers.