Repairs to the roof of a laboratory building at Wrexham Maelor Hospital are expected to cost around £400,000 after crumbling reinforced autoclaved aerated concrete (RAAC) was discovered in the structure.
Crumbling concrete discovered in Pathology Unit
RAAC – a lightweight form of concrete widely used in public buildings between the 1950s and 1990s – has become the focus of growing concern in recent years after it was found to deteriorate over time. The material has been identified in schools, hospitals and other public buildings across the UK, prompting extensive inspections and repair programmes.
The material was discovered in the roof of Wrexham Maelor Hospital's Pathology Unit in January 2025. While the unit is not open to the public, it plays a vital role in the hospital's diagnostic services, housing laboratories that carry out blood analysis, fertility testing and immunology investigations.
Health board seeks contractor for £400k repair
Now 18 months later Betsi Cadwaladr University Health Board has put the repair work out to tender. It is seeking a construction firm able to repair and reinforce the roof – while the building remains operational as a laboratory – for around £400,000.
An inspection by a specialist surveyor on behalf of BCUHB originally identified the problem last year. As soon as it became aware of the issue, the health board installed props to shore up the roof area, which includes heavy air conditioning units. All access to the roof was restricted and North Wales Fire Service warned not to place any load upon the roof section should they need to attend.
Work expected to begin in September
If a contractor can be found, work is expected to begin in September to be completed by the end of March 2027. "The project comprises structural intervention works beneath the existing RAAC flat roof structure serving the main Pathology Laboratory," according to the documents. "The laboratory will remain fully operational throughout the works, requiring carefully managed sequencing and environmental controls. The project scope also includes internal refurbishment works."
