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21 Sep 2023

Current spotlight - Reinforced Autoclaved Aerated Concrete ("RAAC")


The current spotlight on the use of Reinforced Autoclaved Aerated Concrete ("RAAC") started with concerns raised in relation to schools and the subsequent guidance on mitigation measures announced by the Department for Education at the end of August 2023. Despite the focus on schools, the use of RAAC as a construction material in the post-war period was not limited to schools or public sector buildings and, therefore, it is incumbent on all property owners and estate managers to consider the issue of RAAC and the steps which may be required.

What is RAAC and why is its use a risk?

RAAC is a lightweight form of pre-cast concrete which is reinforced with metal and was used because it was cheaper, quicker to produce and considered easier to install than standard reinforced concrete. It was made in factories using fine aggregate chemicals (rather than coarse aggregate), which creates gas bubbles within it.

This method of construction makes it porous and permeable meaning that water ingress can cause the steel reinforcements within it to corrode and also provides it with a lower compressive strength.

RAAC was most commonly used in the production of light weight masonry blocks and structural units such as roof planks and floor units. Over time and without careful management RAAC panels can creep and deflect, exacerbated by water penetration and if their structural integrity becomes compromised, they can fracture and collapse with little or no warning, causing obvious risk or injury, or worse, death of occupants, residents, visitors or even trespassers.

Now commonly considered to be deleterious or a cause of potential long term building loss, the material was used within the UK construction industry predominantly in the period of the 1950s -1980s and, therefore, remains present within the UK's current building stock. The Building Research Establishment considers RAAC to have a design life of 30 years meaning that all of the RAAC produced in the UK and incorporated into UK construction projects is likely to be beyond its expected design life.

Do you have RAAC in your building?

Given that the deficiencies of RAAC as a construction material have been generally known within the construction industry for some time, it is unlikely to have been used within recently constructed properties and, therefore, claims for breach of building contract provisions are expected to be limited.

The Health and Safety Executive has produced guidance for property owners and managers in response to increased awareness of RAAC which provides that steps should be taken to identify whether RAAC is present in buildings.

Appropriate action would include taking the following steps:

  • Identify – Take steps to identify whether your estate contains RAAC, consider the information in your health and safety files and carry out surveys where buildings are at risk of containing RAAC.
  • Assess – Where a survey identifies that RAAC is present, obtain specialist advice from a structural engineer to determine the condition of RAAC and any risks associated with the location of the RAAC.
  • Mitigate – Based on the assessment of the location and condition of RAAC within the property, engage a structural engineer to prepare a suitable action plan.
  • Insurance – Review the terms of your existing property and public liability insurance policies to determine whether they would respond to a RAAC-related incident. Consider whether failure to take appropriate action to identify, assess or mitigate would impact your ability to claim.

The Institution of Structural Engineers has produced guidance on the investigation and assessment of RAAC which can be obtained free from their website.

As a landlord, there is no obligation to notify tenants that a review is being undertaken to identify the presence of RAAC. Where the assessment suggests that the structural integrity of a building is compromised, or there is a need for more invasive property surveys, then to progress matters, the tenants or occupants will have to be notified in order to organise further investigations or to carry out works. Lease terms need to be checked to determine what rights you have for intrusive survey.

Where RAAC is present in combination with asbestos which must be dealt with in accordance with the Control of Asbestos Regulations, any steps taken to remediate or stabilise existing structures or the potential consequences of any collapse due to a failure in durability of the RAAC will need to be carefully considered to avoid exposure of occupiers to asbestos.

What legal risks could you face if you don't take the appropriate action?

  • Defective Premises Act 1972 - Where a landlord is responsible for the maintenance or repair of a premises under a lease, the duty under section 4 of the Defective Premises Act 1972 will be triggered. Under section 4(1) of the Act, a landlord who is responsible for the maintenance or repair of a premises owes a duty of care to "all persons who might reasonably be expected to be affected by the defects" to "take such care as is reasonable in all circumstances to see that they are reasonably safe from personal injury or from damage to their property caused by a relevant defect". The duty is owed if the landlord knows or ought in all the circumstances to have known of the relevant defect.
  • Health and Safety at Work Act 1974 – Employers are under a duty to ensure the health, safety and welfare of its employees and to take such measures as are reasonable where they are in control of a building to ensure (as far as reasonably practicable) that the premises are safe and free from risk to health. This duty will need to be taken into consideration when assessing what are appropriate steps to take within any mitigation plan, particularly where RAAC is present in combination with other hazardous materials.
  • Construction (Design and Management) Regulations 2015 – In addition to the Health and Safety at Work Act 1974, where remediation work is being carried out consideration will need to be given by the person procuring those works as the client to its duties to health and safety in the carrying out of those works in the usual way.
  • Occupiers Liability Act 1957 – Where someone is an occupier or in control of a building, under the Occupiers Liability Act it owes a duty of care to take such steps as are reasonable in the circumstances to keep visitors to its property reasonably safe.
  • Liability for death and/or personal injury under common law – In the event of a building collapse due to RAAC, the occurrence of death or personal injury could lead to liability under common law for those responsible if they have been negligent.
  • Building Safety Act 2022 - Where a building within your estate is one which has to be registered with the Building Safety Regulator as a Higher Risk Building (a "HRB"), the information which you are required to provide on that HRB will include information on the structure of the building and where reinforced concrete has been used, the type of reinforced concrete and, if reinforced concrete large panel systems were used, the time period in which the property was built.

Do I need to disclose RAAC when replying to CPSEs?

It you're aware of RAAC, you'll almost certainly need to disclose that in replies to CPSEs.

Several of the CPSEs seek to flush out information relating to defects in the fabric of a property, most notably CPSE 1 enquiry 8.6, which specifically asks "Has any substance … known or suspected to be unsuitable for its purpose, unstable or hazardous, been used in the present structures forming part of the Property…?

Similarly, if you've identified a potential RAAC problem and are granting a lease, CPSE 3 enquires 1.5 and 1.12 should flush out details of any planned maintenance programmes and cost.

Commercially therefore, it makes sense for sellers/landlords to be up front about any RAAC that they're aware of and to show that they have a costed plan of how they're going to deal with it. That should give a buyer and tenants confidence that the seller or landlord is in control of the issue – and will avoid later delays in the sale/letting process.

Will I be able to recover the cost of repairing or replacing RAAC through the service charge?


As always, the terms of the specific lease will need to be checked.

As an example, if a lease is drafted in simple terms and states that the landlord is obliged to repair the building, and that the tenant is obliged to pay a proportion of the landlords' repairing costs, then the landlord has a good claim for recovery.

Of course, commercial leases are often more complex and a tenant's obligation to pay may be qualified. For example, there may be carve outs for inherent defects or obligations on the landlord to make claims against third parties before pushing costs thought the service charge. Even if there are carve outs for inherent defects, there are good arguments that RAAC doesn't amount to an inherent defect in any event, given, amongst other things, that the limited shelf life of RAAC was always known about.

Similarly, if landlords choose to replace RAAC which is in good condition, they are unlikely to be able to argue that this amounts to "repair" as, put simply, the RAAC is not in disrepair.

The insurance position should also be investigated. The provisions of the policy for the building should be checked to see what, if anything, is covered – and the "insured risks" provisions of lease will also need to be reviewed.