Overview:
Work is underway across Scotland to survey all NHS buildings which may potentially contain Reinforced Autoclaved Aerated Concrete (RAAC).
RAAC is a lightweight form of concrete used mainly in roof, floor, and wall construction in the UK during the second half of the 20th century. It has been found in a range of buildings, both in the public and private sector.
The material was often most used in the construction of roofs and floors and is known to be less durable than other forms of concrete, particularly where it has been damaged by water or where it was not formed correctly during the original fabrication. RAAC was used widely from the 1960’s until it was phased out in the 1990’s.
NHS Fife has identified a number of buildings within our Estate which may potential contain RAAC and has supplied this information to NHS Assure. This list of buildings identified was a desk-based exercise based primarily on when the buildings – or parts of buildings – were built. While it is likely that parts of some of our buildings will contain RAAC, we will only know definitively once more detailed surveys are carried out.
Background
A SCOSS (Standing Committee on Structural Safety) Alert of May 2019 regarding the failure of Reinforced Autoclaved Aerated Concrete (RAAC) Planks raised concerns across the public sector about the presence of such material in buildings after a flat roof collapse in a school in England late 2018.
Thereafter, work was undertaken to identify the extent of possible high-risk properties within the NHS Fife portfolio. These were noted specifically as those properties which fell within a possible construction period between the 1960’s and 1990’s. This period has been identified through research following a series of failures in the 1980’s. Buildings out with this period are unlikely to be affected.
What is RAAC?
Reinforced Autoclaved Aerated Concrete (RAAC) is a lightweight, ‘bubbly’ form of concrete commonly used in construction between the 1950s and mid-1990s. It is predominantly found as precast panels in roofs (commonly flat roofs, sometimes pitched) and occasionally in floors and walls.
RAAC differs from normal concrete in that it contains no coarse aggregate and was manufactured using fine aggregates with chemical additives to create gas bubbles and heated to cure the compound. It is relatively weak with a low bond capacity with reinforcement. When reinforced (RAAC) protection of the reinforcement against corrosion was provided by a bituminous or a cement latex coating applied to the reinforcement prior to casting.
Appearance & texture
RAAC panels are light-grey or white in appearance, the underside of the panels will appear smooth. The inside of the planks will appear bubbly, often described as looking like an Aero bar. Unlike traditional concrete, there will not be visible stones (aggregate) in the panel.
Use of RAAC
The material has been used in two main structural elements: lightweight masonry blocks and structural units (roof planks, wall, and floor units).
NHS Scotland Reinforced Autoclaved Aerated Concrete (RAAC) Survey Programme
NHS Scotland Assure (part of NHS National Services Scotland) are co-ordinating a programme of work to carry out detailed surveys of all properties across the NHS estate that have been identified as potentially containing RAAC. A list of all buildings being surveyed across the NHS Estate in Scotland has been published on the NHS National Service Scotland website.
An update on the survey programme progress will be published weekly on the NHS Assure website, including whether RAAC has been identified or not on properties surveyed. This process is being carried out across Scotland and we expect all buildings identified in Fife to have been surveyed in the Autumn.
The results of these surveys will provide information on whether RAAC is present and whether any remedial action is needed.
Progress of NHS Scotland RAAC Survey Programme in Fife
The process of surveying the identified buildings, that met the necessary criteria in NHS Fife’s Estate has already begun. Details of these buildings, and the progress made in Fife as part of the NHS Scotland RAAC Survey “Discovery” Programme, are outlined below.
