LGA Advises to Check Roofs for RAAC
The Local Government Association (LGA) is advising their members to check as a matter of urgency, if any buildings in their estates have roofs, floors, cladding or walls made of Reinforced Autoclaved Aerated Concrete (RAAC).
What is RAAC?
RAAC is a lightweight form of concrete used in roof, floor, cladding and wall construction in the UK from the mid-1950s to the mid-1980. It was used primarily in offices and schools, but RAAC has been found in a wide range of buildings, not all of which are still in the public sector.
Problems with RAAC roof planks have been known since the early 1990s and many have been replaced with alternative structural roofs or by introduction of secondary supports. There is no central register of buildings with RAAC roof planks and the collapse of a school roof in late 2018 proves that many structures still have potentially dangerous roofs or flooring. The problem may be more serious than previously appreciated and that many building owners are not aware that it is present in their property.
Warning Signs of RAAC Failure
- Significant cracking and disruption of the planks near the support;
- Any planks that have deflected more than 1/100 of the span, or a significant number of planks that have deflections approaching this magnitude;
- A number of the planks have very small bearing widths (less than 40mm);
- The roof has been re-surfaced since original construction - this is particularly an issue if the load has been increased or the re-surfacing has a black finish and the previous surface did not;
- There is significant ponding on the roof; and
- The roof is leaking or has leaked in the past.
What to do if You Suspect You Have RAAC in Your Facility
- Identify any properties constructed using RAAC and validate the potential risk appropriately;
- Consider and monitor the possible impact of reduced maintenance regimes on the condition of your property portfolio, in particular where RAAC is used; and
- Relevant staff should also familiarise themselves with the CROSS Report: RAAC roof planks – sharing experiences and the Institution of Structural Engineers Report: Guidance on identification and remediation solutions for RAAC planks.
Hospital Buildings
In a report published earlier this year by The Metro, it was revealed that more than 30 hospital buildings across 16 hospital trusts in England have roofs so rotten they could collapse at any moment.
The hospital’s chief executive Caroline Shaw told The Sunday Times: "The roof is like a chocolate Aero bar – there are bubbles in the concrete and we’re checking it daily to make sure those bubbles don’t break and the roof doesn’t come down."
A Department of Health spokesperson said they have "provided more than £4billion for trusts to improve infrastructure and maintain or refurbish their premises."
They added that over £685 million has been set aside to directly address the issue of crumbling RAAC roofing.
Roof Collapses
In 2018, a series of partial and full roof collapses in school buildings were reported, with RAAC being a significant cause. Immediately, schools and education facilities were advised to check their premises as a matter of urgency and take remedial action where necessary.
The Standing Committee on Structural Safety (SCOSS) released an Alert in May 2019, indicating that this is a broader issue, as RAAC roof planks were used across a wide range of structures. This alert promoted nationwide attention, and the government set aside £100 million to carry out urgent remediation work at NHS sites affected by RAAC roof plank issues.
Last year, the Local Government Association’s building safety spokesperson warned of the consequences of a RAAC roof collapse after temporary emergency measures were implemented at several NHS hospitals which have reinforced autoclaved aerated concrete (RAAC) planks within their walls and ceilings.
The West Suffolk hospital, in Bury St Edmunds, had to install 27 metal supports under RAAC planks, and has since, fitted the hospital’s entire roof with monitoring equipment to catch any further deterioration or weakness in the planks.
The Queen Elizabeth Hospital in Norfolk had to have more than 200 supports in place and Hinchingbrooke Hospital has set a weight limit on patients at two of its theatres due to concerns about the condition of the building’s RAAC planks.
NHS East of England also reportedly developed a Mass Casualty Plan and trained staff to deal with events such as a structural failure.
At the time, Local Government Association’s building safety spokesperson Lord Porter said that “the consequences of an RAAC roof collapse are unthinkable”.
in 2021, the government announced that it had set aside £110M to carry out "urgent remediation" work at hospitals with faulty RAAC planks.