RAAC – Reinforced Autoclaved Aerated Concrete

You will probably be aware from the news that there is considerable concern regarding the possible failure of Reinforced Autoclaved Aerated Concrete (RAAC) in schools and other public buildings. It is important to realise that many blocks of flats, particularly those built in the 1950s, 60s and 70s, and less so in the 80s, may also possess this material, principally used in flat roofs, but which may also be present in floors, walls and pitched roofs.

There have been failures and these can be sudden, hence the requirement to establish if RAAC is present and its condition.

RAAC reinforced autoclaved aerated concrete close up
The failure of RAAC panels can be a danger to life.
[Credit: Nikolay Malshakov]

RAAC Investigations

As Structural Engineers, Philip Goacher Associates are ideally placed to provide initial guidance and further investigations as necessary to assess firstly whether your property’s roof, floors, etc., have RAAC present. A simple visual inspection and local removal of a small portion of concrete will identify if the property has been constructed with this material, as the panels are generally very soft and can be easily dented with a screwdriver or nail. We can generally undertake this investigative work ourselves without the need for a general builder.

However, if there is a covering over the panel an asbestos report will be required before we can assist, as panel coverings (e.g. artex) generally contain asbestos.

Next Steps

If RAAC is identified, then further investigations will be tailored to the particular panels present. This will involve a more detailed visual inspection and possibly some more destructive investigation to check the general condition of the panels. If the panels are present but found to be in a satisfactory condition, then yearly monitoring by a competent person should be all that is required to ensure safety and stability.

How to Repair RAAC Panels

If the RAAC is found to be in poor condition, then we are able to design additional/alternative support structures to strengthen the panels. In extreme cases, where we feel failure is imminent, the panels will need to be removed and replaced – however, this is likely to be quite rare, and additional support structure should be all that is required.

If you are concerned about RAAC, please get in touch by email or telephone. You can find out more about RAAC in schools by visiting the Government website.

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