RAAC and asbestos: A guide to understanding the hidden threats of building materials

RAAC and asbestos: A guide to understanding the hidden threats of building materials

RAAC and asbestos were widely used in British building projects between the 1950s and 1990s. Once lauded for their cost-effectiveness, thermal, and fire resistant properties, today these materials present serious health risks. The combination of both materials is particularly dangerous.

In this guide, we explore the hidden connection between RAAC and asbestos, how the collapse or removal of one can trigger the dangers of the other, and what you need to do if you suspect either material is present in your building.

Understanding the risks of RAAC and asbestos

Before proceeding, it is essential to define both substances, understand their sources, and explore their associated risks.

RAAC

Reinforced Autoclaved Aerated Concrete (RAAC) is a lightweight building material that has been used extensively in public and industrial buildings since the mid-20th century, due to its cost efficiency and fire-resistant properties.

However, RAAC is significantly less robust than traditional concrete. Over time, moisture can weaken the material, leading to the corrosion of embedded steel reinforcement and an increased risk of sudden structural failure.

Asbestos

Asbestos is a group of six naturally occurring fibrous minerals known for their strength, heat resistance and insulating properties. It is common in insulation, ceiling tiles and roofs.

Like RAAC, asbestos can pose a serious health risk. Undisturbed, asbestos is not considered harmful however, movement of Asbestos containing Materials (ACM’s) can release asbestos fibres. When breathed, these fibres can cause cancer.and mesothelioma The UK banned the use of asbestos partially in 1984 and completely in 1999, but it remains present in many existing buildings.

Is there a link between RAAC and asbestos?

While there’s no definitive link between the presence of RAAC and the presence of asbestos, both materials were widely used during the post-war construction period. Consequently, many buildings, particularly those in the education, healthcare and public sectors, contain both materials.

The simultaneous presence of RAAC and asbestos creates a compounded risk scenario. Not only is there a threat of structural failure from deteriorating RAAC, but such failures may also disturb adjacent asbestos-containing materials, exacerbating the danger.

The problem is particularly prevalent in schools. A 2019 Department of Education study revealed that 81% of schools are known to have asbestos. More recently, RAAC has been found present in 234 schools and colleges, or around one per cent. In half of these cases, schools require extensive rebuilding or refurbishment, which makes the threat of asbestos even greater.

The problem of RAAC collapse and asbestos release

The deterioration, remediation or collapse of RAAC elements can result in the physical disturbance of asbestos. For example, a failing RAAC roof panel might cause ceiling tiles or insulation containing asbestos to fall. Alternatively, the process of removing RAAC from a school roof could disturb asbestos that is hidden in ceiling voids.

Even slight movement can release dangerous asbestos fibres into the air, potentially exposing building occupants and emergency personnel, and compounding the impact of RAAC collapse. The risk is especially high in buildings where maintenance records are incomplete or where RAAC and asbestos are hidden behind false ceilings or other fixtures.

The importance of checking for asbestos when assessing RAAC

Given the likely presence of both materials and the risk of disturbing asbestos when removing RAAC, it is essential to survey for asbestos concurrently with RAAC. This is particularly relevant for schools, hospitals and public buildings.

Of course, the same applies to buildings where asbestos is known to be present. If the building dates from the period when RAAC was used, a RAAC survey should be a priority.

How to manage and remove RAAC and asbestos

If you find either RAAC or asbestos in your building, there is no immediate call for alarm. Asbestos only presents a risk when disturbed. In many cases, RAAC panels also pose no immediate threat to buildings or their occupants.

If further action is required, however, here is what you need to know.

Managing and removing asbestos

Managing asbestos begins with a thorough survey carried out by a licensed professional. The findings are used to create an asbestos register and management plan. If the asbestos is in good condition and unlikely to be disturbed, it may be managed in place with regular inspections. However, if ACMs are damaged or in locations subject to disturbance, removal becomes necessary.

Licensed asbestos contractors must perform removal following strict safety protocols. The area should be sealed off and air quality monitored before, during and after removal. Waste must be disposed of at licensed facilities.

Managing, mitigating and removing RAAC

Once RAAC is identified, its condition must be assessed by structural engineers. Risk levels are determined based on location, visible deterioration, moisture ingress and signs of corrosion.

Several RAAC management options are available to building owners and occupants, including:

• Condition monitoring. Regular on-site assessments from structural engineers can assess deterioration over time.
• Interim safety measures. Acrow props, crash decks and internal scaffolding can be used to provide temporary support.
• Structural solutions. Non-intrusive, long-term structural strengthening solutions, like steel beams and timber struts, can mitigate structural failures.
• RAAC Lift®. Our cost-effective and pioneering solution is engineered to solve the challenges of RAAC plank deflection.

When removal is necessary, teams should take care to cause minimal damage and disruption to the surrounding area. This will reduce the likelihood of an asbestos disturbance and minimise the associated risk.

What to do if you have asbestos or RAAC

RAAC and asbestos can pose serious health risks. But you can minimise those risks by taking the appropriate action early. This includes:

• Identifying and verifying the presence of both materials
• Commissioning structural surveys
• Engaging licensed and chartered professionals
• Executing coordinated remediation and removal work where necessary

At RCS, we’re here to help. We offer comprehensive RAAC surveys that also assess the presence of asbestos and the danger it poses. We are experts in our field. We only employ experienced surveyors with extensive RAAC experience and have surveyed over 200 buildings, including the headquarters of the Institution of Structural Engineers.

Should we detect RAAC and asbestos, we offer a fully managed end-to-end service to help you mitigate the risks as quickly and cost-effectively as possible. Speak to one of our experts for more information or book an introductory call.