The RAAC Concrete Issue Summarized Quickly
This abstract summarizes the urgent issue facing numerous UK schools due to concerns surrounding reinforced autoclaved aerated concrete (RAAC). A sudden change in government guidance, prompted by the material’s deterioration and potential for structural failure, has led over 150 schools to either close unsafe buildings or implement temporary safety measures, such as propping, just before the commencement of the 2023–24 school year. RAAC, a lightweight concrete used extensively in construction from the post-war period until the mid-1990s, is now at risk of failure in some structures due to its inherent lack of durability and a lifespan of approximately 30 years. This situation has not only affected educational institutions but also buildings across the UK’s National Health Service (NHS), Ministry of Justice, other public sectors, the private sector, and residential areas. The government’s response, including school inspections since 2018 and recent funding announcements for mitigation measures, highlights the broader implications of RAAC’s use and the challenges in managing its legacy. This abstract underscores the debate around the timing of the recognition of RAAC issues and the steps taken to address them, reflecting on the impact on school operations and the wider concerns regarding building safety in the UK.
Numerous schools across the UK have been compelled to shut down specific buildings urgently following a sudden update in government advice concerning RAAC. A concise explainer has been crafted to quickly bring you up to speed on the essentials.
A significant news event is unfolding in the UK as the government has revised its guidance, instructing over 150 schools with hazardous buildings to either close them or implement temporary safety measures, such as propping, right before the new school year of 2023–24 begins. This action stems from concerns regarding RAAC, or reinforced autoclaved aerated concrete.
RAAC, a lightweight concrete variant, was predominantly used in the construction of roofs, walls, and floors from the post-war era until the mid-1990s, especially from the 1950s to the 1970s, due to its cost-effectiveness and ease of production. Typically manufactured in long planks, RAAC can be challenging to inspect or detect when concealed by ceiling, wall coverings, or floor coverings like carpets.
Unlike conventional concrete, RAAC lacks aggregate, making it less sturdy and reducing its lifespan to approximately 30 years. This reduced durability is a key factor why some RAAC structures now pose a collapse risk, particularly if they have not been adequately maintained. RAAC is present in various types of buildings, not only schools. Efforts to identify and remove RAAC are underway in the UK’s NHS, Ministry of Justice, other public entities, the private sector, and among some homeowners.
There is ongoing debate about when the problems with RAAC were initially recognized and when they should have been addressed. Following a collapse in 2018, the UK government began inspecting schools, and recent months have seen 2–3 additional RAAC failures, prompting the government to urgently revise its guidance. The Department for Education is currently assisting schools in implementing safety measures like propping or relocating to other facilities, with Chancellor Jeremy Hunt stating on BBC News that the funding for these measures will come from pre-existing, unallocated budgets rather than new funding. Currently, it seems a small fraction of the UK’s approximately 22,000 schools are impacted, with most schools set to reopen on Tuesday, 5 September.
