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RAAC – Does it affect my building?

9th October 2023

Reinforced Autoclaved Aerated Concrete (RAAC) has lately been in the news, with over 100 buildings, mainly schools,  closing due to health and safety issues. 

It is a building material used as an alternative to traditional concrete.  RAAC was formerly thought to be perfect for moulding into lighter, pre-formed concrete components, however the material has deteriorated, sagged, and aggravated building difficulties over time.

Here’s everything we know currently about the substance and whether it affects your building.

What exactly is Reinforced Autoclaved Aerated Concrete (RAAC)?

RAAC is a reinforced version of lightweight concrete utilised for creating panels or boards that, unlike regular concrete, consists of no aggregate. It was mostly utilised in flat roofing but also for certain floor and wall panel development in the UK from the mid-1950s to the mid-1990s and has been utilised in a variety of building categories, both commercial and residential, but is thought to be more common in schools, hospitals and public buildings. It is often defined by its ‘bubbly’ texture.

Source: Dfe IStruct

Why are people worried about RAAC?

RAAC has  a lifespan of around 30 years and has shown to be less durable than other concrete construction supplies, with numerous applications considered life-expired.  The Health and Safety Executive (HSE) recently recommended that RAAC has outlived its intended lifespan, potentially resulting in an unexpected collapse, despite the fact that RAAC can last longer if the structure is carefully maintained. RAAC is susceptible to failure, especially if it has been damaged by water entry from leaky roofing materials, which promotes reinforcement corrosion. Added to that, if the RAAC wasn’t formed appropriately when originally manufactured, was inadequately fitted, or if on-site work such as cutting the reinforcement bars was performed, this might significantly diminish the end bearing capacity of the planks and lead to failure.

What do existing reports show?

Collaborative Reporting for Safer Structures UK (CROSS-UK), a confidential system for reporting which enables experts who work in the construction industry to report on fire and structural security problems recently released a report regarding a RAAC evaluation that was undertaken by persons not suitably experienced. The report’s Key Learning Outcomes for property owners, managers, surveyors, and others responsible for building safety are as follows:

  • If poor RAAC assessments are relied on, building users may suffer considerable harm.
  • If RAAC is suspected, an examination and assessment of reinforced concrete structures should be performed by a Chartered Structural or Chartered Civil Engineer.
  • If RAAC is confirmed, it is recommended that the building and its use be risk assessed.
  • An engineer with RAAC knowledge and experience should contribute to risk assessments; and
  • The document Reinforced Autoclaved Aerated Concrete: Estates Guidance by the Department for Education (DfE) includes recommendations useful when engaging an engineer to assess RAAC.

Was RAAC used in houses and residential blocks?

Some building experts believe that it is likely RAAC was used in homes built between 1950 and 1990, in particular social housing. RAAC has already been discovered in some housing and councils have been instructed to check buildings built during this period within their areas. However, newer buildings and developments are less likely to have had RAAC used in the structure of their building. It is thought that this building material was mainly used in private and public sector buildings, with schools, hospitals and offices having the greatest impact.

What should I do if RAAC is in my building?

Depending on whether you are a freeholder or leaseholder of a property, can determine what action you are able to take. If you are a freeholder, you will most likely be responsible for repairs including to the structure of the building, you may wish to instruct a survey or check with the developer as to whether RAAC was used. If you are a leaseholder, you will need to refer to the terms of your lease. The lease will set out your obligation, however the landlord or managing agent will be responsible for any repairs and the structure of the building.

You can usually tell by eye due to its texture whether or not your building would contain RAAC, if you are unsure, we would recommend contact either your developer or managing agent to check.


Whether you are a landlord with a single property, or a leaseholder in a block of apartments  we have the experience and expertise to assist you in identifying RAAC. Seraph’s team can instruct the relevant checks in buildings to identify and locate RAAC. Seraph can make immediate and long-term recommendations to ensure the structural safety and integrity of your building.

We will continue to provide any additional updates and  keep you updated via our newsletters. If you have any queries or concerns following the recent news stories about  Reinforced Autoclaved Aerated Concrete (RAAC) we are happy to help.