Reinforced Autoclaved Aerated Concrete (RAAC) – what we know so far:
In August 2023, the Government ordered more than 100 schools to vacate areas made with RAAC – unless or until suitable mitigations were put in place.
At the time, the Cabinet Office confirmed that 34 other public buildings had also been found to feature RAAC. These include 24 hospitals sites with RAAC plank construction in whole or a significant part of their estate. Seven of these need a full replacement and will be rebuilt before 2030.
By 16 October 2023, the list of schools and colleges where the presence of RAAC had been confirmed was published. A total of 202 settings are providing face-to-face learning for all pupils, and 12 settings have put hybrid arrangements in place. None have had to move to remote learning fulltime.
All those responsible for managing, maintaining, and altering government buildings are being advised to assess RAAC and seek specialist advice to develop management plans.
What is RAAC?
RAAC is a reinforced form of lightweight concrete used to form panels or planks. Unlike common concrete, it contains no aggregate and was commonly used in construction between the 1950s and mid-1990s. RAAC is predominantly found in precast panels in flat roofs, and occasionally in floors and walls. RAAC is believed to be more common in schools, hospitals and public buildings.
As highlighted by RICS, RAAC has proven to be not as durable as other concrete building materials. There is a risk RAAC can fail suddenly, particularly if it has been damaged by water ingress from leaking roofs. The end bearing capacity of the planks can be dramatically reduced because of poor original installation or cutting the reinforcement bars on site.
What is the impact of RAAC?
The impact of RAAC can vary. According to the Department of Education, some settings may have very little RAAC present which means limited disruption such as the temporary closure of one school space, like a single classroom. In most cases, children will be able to continue attending school as normal.
How is the Government supporting schools and education settings affected by RAAC?
All settings known to contain RAAC will be assigned a dedicated DfE caseworker who will work with the responsible body to assess the site’s particular needs and help them put in place individual solutions.
The Government has also published further guidance for schools and colleges on identifying and managing RAAC. This sets out how the Department for Education will provide support and capital funding to schools and other settings so that face-to-face education continues safely.
How is the need for RAAC repairs and RAAC removal identified?
Department for Education (DfE) guidance outlines the following principles for identifying RAAC and the possible need for RAAC repairs or RAAC removal:
- Typically, panels are 600mm wide.
- There are distinctive, regularly spaced V-shaped grooves.
- Panels are white or light grey.
- When accessing records and drawings relating to the building, planks may be referred to by names such as Siporex, Durox, Celcon, Hebel, Xella or Ytong.
- The inside of the planks will appear bubbly, like an Aero chocolate bar.
- There will be no visible stones in them.
If RAAC is discovered, a risk assessment must be carried out. An appropriately experienced chartered structural engineer or chartered building surveyor should be appointed for identification and inspection work.
How is the construction industry helping to deliver RAAC repairs, removal, reinforcement and demolition?
As a highly experienced public sector contractor, we regularly work with our clients to overcome obstacles and problem solve. We are experienced in delivering solutions for RAAC, whether this be RAAC repairs, removal, demolition or reinforcement to maintain use of the building.
When RAAC is identified, speed is of the essence. Corrective measures and repairs must be carried out quickly and effectively to deliver RAAC repairs and rectify the issue ensuring the safest possible environment. At Diamond Build, we are working closely with our public sector clients to meet this objective and carry out RAAC repairs and reinforcement while minimising disruption.
Our expertise saw us recently complete RAAC repairs for a London school. The project was handed over within seven weeks to minimise disruption for students and staff.
Following the isolation of mechanical and electrical services, the existing ceiling and timber supports were removed from the top floor of a building. Timber and steel joists were then installed to support the RAAC panels and improve the load bearing capacity.
Prior to reinstating power, data cabling and fire alarm systems, new lighting and heating equipment was installed. A new suspended ceiling system was then fitted, completing the works.
As a specialist refurbishment contractor for the public sector, our team was able to mobilise quickly to help the school and complete the urgent RAAC repairs. Most of the work was carried out during the summer holidays to minimise disruption.
With vast experience of refurbishing occupied sites, we were able to complete the final part of the project when the pupils returned to school, eliminating the need for any closure.
If you are seeking a construction partner with experience in RAAC repairs, reinforcement or demolition, please contact our team to discuss your requirements.