What is RAAC concrete and why is it a safety risk?

What is RAAC concrete and why is it a safety risk? Educational Architecture

In architecture and construction, the spotlight has recently swung onto a somewhat obscure but critically important material: RAAC. RAAC concrete is stirring up conversations in the building and construction industry, posing questions about its safety and use. This article will look at what exactly RAAC is, the concerns it raises, and how it impacts structures like schools. This guide offers straightforward insights into RAAC’s role in our buildings.


What is RAAC?

Reinforced Autoclaved Aerated Concrete, or RAAC, is not your everyday building block. Introduced between the 1950s and mid-1990s, it was the go-to for builders who wanted something light yet effective for building insulation.

Unlike the heavy, dense concrete we’re used to, RAAC does not contain the usual gravel or stone bits, making it lighter and more fit for purpose. However, this lighter material, therefore, also behaves differently from other, more conventional construction materials.

This difference created some unique hurdles, especially when it came to ensuring that it could withstand the test of time and use.

What does RAAC look like?

RAAC panels have a distinctive ‘bubbly’ texture, marked by a series of small air pockets. These pockets, created during the aerating process, give RAAC its light-weight and insulative properties. Over time, RAAC may show signs of wear, like cracking or water damage, making it easier to spot in older buildings. Its lighter colour and less dense structure compared to traditional concrete can also help identify RAAC elements in buildings.

RAAC vs Breeze Blocks: what is the difference?

When comparing RAAC with breeze blocks (also known as concrete masonry units), key distinctions can be made when looking at density, durability, and moisture resistance. These factors play a crucial role in a material’s suitability for specific construction purposes.

Breeze blocks are much denser in their composition, so they are much more durable and buildings last much longer. This robustness makes them less susceptible to the effects of moisture infiltration, a common issue with RAAC that can lead to significant structural concerns that may cause greater damage further down the line.

Why is RAAC unsafe?

So, what is the problem with RAAC? When RAAC first hit the scene, it was all the rage because it was easy to use and didn’t cost a fortune. But as the years ticked by, RAAC began to show its age and lack of structure sophistication. The problem with RAAC is that it can be temperamental when it comes into contact with water. This type of concrete is like a sponge, and when it gets wet, it can weaken, risking the building’s integrity, especially in parts of the structure that hold everything up. Back in its heyday, manufacturers did not provide sufficient information on RAAC’s lifespan, leaving us today with some safety puzzles to solve in buildings that relied on it heavily.

Identifying RAAC in buildings

Spotting RAAC within a building requires a keen eye for detail and an understanding of what sets it apart from more traditional concrete. Here’s a more thorough breakdown of how to recognise RAAC in buildings:

Look for the lightweights

RAAC panels are noticeably lighter than their conventional concrete counterparts. This attribute made them popular choices for parts of buildings that could benefit from a lighter touch, like flat roofs or external cladding. Their lighter weight doesn’t come without its drawbacks, as it often means they’re not as strong or durable as denser forms of concrete.

The texture tells a tale

One of the most distinctive features of RAAC building material is its texture. While traditional concrete is relatively smooth and dense, RAAC has a unique ‘bubbly’ appearance. This is due to the aerating process it goes through during manufacturing, which introduces tiny air pockets into the material. These air pockets contribute to its insulation properties but also, on the downside, make it more susceptible to wear and tear.

Signs of age

RAAC panels, especially those that have been exposed to the elements for decades, show characteristic signs of deterioration. Visible cracking is a common issue, as the material’s structure can be compromised over time. Additionally, moisture penetration is one of the red flags associated with RAAC. RAAC’s porous nature makes it particularly vulnerable to water, leading to damage that can compromise the structural integrity of the building.

Where to look

RAAC was often used in specific areas of a building where its lightweight and insulative properties would be most beneficial. Besides roofs and cladding, RAAC may also be found in internal walls or as part of the structure of balconies. When conducting a building inspection, these are crucial areas to examine for signs of RAAC.

Professional insight

Identifying RAAC’s risks is key. If you think your building might have RAAC, getting an expert’s opinion is essential. Structural engineers or building inspectors can check the material’s condition, see how much damage there is, and suggest what to do next. This could mean full checks and making plans to fix or replace RAAC safely. WindsorPatania Architecture can guide you through dealing with RAAC. You can book a free call to talk about your concerns and what steps to take.

The Use of RAAC in Schools

The reliance on Reinforced Autoclaved Aerated Concrete (RAAC) in educational buildings, alongside hospitals and airports, and the presence of RAAC in public buildings has led to a significant reassessment of building safety protocols across the UK.

Finding RAAC in numerous schools in the UK has prompted an urgent response to determine the extent of its use and the potential risks to occupants. Some schools have had to close immediately for in-depth RAAC safety inspections, and the discoveries have also sparked greater efforts to catalogue and evaluate the most affected buildings.

Safety and well-being of students and staff drives the initiative to pinpoint which schools have RAAC materials integrated into their construction. This mission has led to widespread surveys and exhaustive assessments, designed to identify any structural vulnerabilities and address them proactively. Ensuring educational facilities are secure and structurally sound is paramount, highlighting the importance of this ongoing investigation and remediation effort.

Addressing the RAAC challenge

Confronting the issues associated with RAAC in buildings, particularly schools, demands a dynamic approach that also explores possible solutions. This involves thorough inspections and RAAC risk assessments to understand the extent of RAAC usage and its condition.

Buildings identified with RAAC must undergo rigorous structural evaluations to determine the immediate safety measures required and to devise a plan for long-term remediation, which may include the replacement or reinforcement of RAAC components.

Working with RAAC is a challenge. When coupled with the potential costs and complexities of remediation efforts, it becomes obviously necessary for specialised expertise and robust government support.

Collaboration between building owners, educational authorities, construction experts, and policymakers is essential for RAAC remediation. Together, these stakeholders need to ensure that all buildings, especially schools, are safe and conducive to their intended use, thereby addressing the RAAC predicament with the seriousness and diligence it warrants.

RAAC in buildings summed up

RAAC is a significant challenge within the construction and building management sectors. Its history, characteristics, and risks call for a proactive and informed response from professionals in the industry as well as government intervention.

Identifying and addressing RAAC in buildings, especially schools, will help to remove some of the immediate risks and ensure the continued safety and sustainability of our buildings moving forward.

The challenges encountered with RAAC should provide industry players with lessons learned and the information needed to help implement better practices and materials selection in construction. We should see more contributions to safer, more resilient buildings in the future.

If you come across RAAC in your building, you may feel a twinge of distress. However, there’s no need to worry.  WindsorPatania can help you take on these challenges and present opportunities for innovation and safety design.

Our team of experts is adept at conducting thorough assessments, identifying RAAC risks, and devising plans for remediation or redevelopment. We can help you transform potential hazards into safe, sustainable environments.

At WindsorPatania Architecture, we are there to work with you collaboratively to help you solve problems. We’re about foreseeing potential challenges and turning them into opportunities for growth and improvement.

Learn more about how we can assist with your RAAC concerns at our Education Architecture page.

If you are ready to take the next step, book a free discovery call with us today, and let’s explore how we can transform your property into a safe, efficient, and innovative space.


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