The East and North Hertfordshire NHS Trust has completed a survey of the buildings on the Lister Hospital site in Stevenage, looking for the use of reinforced aerated autoclaved concrete (RAAC).

It comes after NHS England instructed all NHS trusts to assess their estates, following national concern over the use of RAAC in public buildings, including schools and hospitals.

RAAC is a lightweight material that was used mostly in flat roofing, but also in floors and walls, between the 1950s and 1990s.

It is a cheaper alternative to standard concrete, but it is less durable and has a lifespan of around 30 years.


The Health and Safety Executive says RAAC is now beyond its lifespan and may "collapse with little or no notice".

A spokesperson for the East and North Hertfordshire NHS Trust said: "Making sure that all buildings at our trust are safe and suitable for patients, staff and visitors is a top priority.

"Surveys were conducted at Lister Hospital in August, and we can confirm that RAAC was not used to construct any of the buildings at this site.

"Initial assessments of buildings at additional sites are under way."

Meanwhile, Hertfordshire County Council says it carried out surveys in 2020 and 2021 on 317 schools constructed between 1959 and 1989. This identified three schools that needed remediation works, and those works were completed in 2022.