The Crisis of Reinforced Autoclaved Aerated Concrete

A Ticking Time Bomb in Our Buildings

Reinforced Autoclaved Aerated Concrete (RAAC) ushered in a new age of construction in the 1960s and 1970s. Its lightweight properties, insulating capacity, and speedy installation allowed the industry to revolutionise Britain’s landscape.

Fast forward to the present day and we’re witnessing its defects form a national crisis. At Auburn, we are keen to examine the problems affecting buildings and what steps are needed to mitigate future risks.

What is the RAAC problem?

Reinforced Autoclaved Aerated Concrete (RAAC) is a type of lightweight concrete. It’s produced by introducing air or gas into a slurry composed of portland cement and refined siliceous material. Once mixed, this material is cast into blocks or panels and cured under high pressure and temperature, forming a robust, insulating, and lightweight building material.

The RAAC issue is its long-term durability. The embedded reinforcement steel panels made from 1960 to the early 1980s are susceptible to corrosion. When the steel corrodes, it expands, leading to cracks and, in the worst-case scenario, catastrophic failure of the RAAC panel. This kind of failure can result in large sections of a building's ceiling or roof collapsing without much warning.

Safety Concerns

The structural integrity of RAAC buildings is compromised. In some cases, parts of roofs or ceilings have unexpectedly collapsed, posing a significant safety threat to occupants. Poorly maintained roofs have meant that water ingress has significantly worsened the problem. This, therefore, needs to be closely monitored.

Financial, Insurance, and Real Estate Concerns

RAAC being surveyed at a hospital.

Buildings found to contain RAAC panels most likely need expensive remedial work. This is either to replace the panels entirely or to ensure they are safe for continued use.

As awareness of the RAAC issue grows, there are implications for property values. As a result, insurance companies might be reluctant to cover properties with RAAC or charge higher premiums. Both will have serious implications for the markets.

Auburn’s Way Forward

Addressing the Crisis to deal with the RAAC crisis is utterly vital for the industry. At Auburn, we believe a multi-faceted approach is necessary.

The first step is to identify buildings that might contain RAAC panels. This involves reviewing construction records, physical inspection, and potentially lab testing of samples. Once identified, a thorough structural assessment is crucial to determine the extent of any degradation.

Remedial Actions

If RAAC panels are found to be deteriorating, action will vary from monitoring the panels (if degradation is minimal) to complete replacement in more severe cases. It's important to consult with structural engineers experienced with RAAC to determine the best course of action.

Awareness Campaigns

Auburn’s sustainable RAAC safe projects underway.

Property owners, property managers, and tenants should be made aware of the risks associated with RAAC. Local governments and industry associations can significantly disseminate information and guidelines on addressing the RAAC issue.

Review Building Standards

There's a need to re-evaluate the building standards and codes that allowed the widespread use of RAAC panels. While the use of RAAC has diminished in recent decades, understanding the missteps is the only way to ensure a safer, more sustainable future.

While RAAC was once seen as a revolutionary building material, it has significant flaws that pose safety and financial risks. It’s a stark reminder of the importance of testing as society continues to progress.

The Future

The RAAC crisis serves as a stark reminder of the importance of thorough testing to fully understand the properties of construction materials, suitable inspection and building operational maintenance regimes to negate deterioration over the long term.

Addressing the issue will require cooperation from property owners, engineers, local governments, and the construction industry. With our expertise, Auburn relishes the challenge of improving people's and institution’s lives.