Concrete closures: reinforced autoclaved aerated concrete and Scottish public buildings

Recent reporting throughout the UK on reinforced autoclaved aerated concrete (RAAC) has heightened public awareness and concern around this issue in Scotland.  

This week, identification of RAAC panels within Airdrie Sheriff Court has led to court rooms being closed, pending investigation and remedial action. This risks delays in court business during efforts to reduce backlogs created by the COVID-19 pandemic. Liam McArthur MSP has stated that ten further Scottish courts are being investigated, with the potential for significant further disruption.

What is RAAC?

RAAC is a lightweight form of concrete which was used as an alternative to conventional concrete between the 1950s and 1990s. It was commonly used in roofing and wall construction in public sector buildings. It has a lifespan of around 30 years and therefore many RAAC structures are now past their shelf life.

Background

The Department of Education (DfE) issued a high alert in summer 2023, highlighting that the ongoing deterioration of RAAC could result in structural damage to buildings. In turn, this Westminster alert increased attention to the use of RAAC in public buildings in Scotland.

Recent publicity has arisen from a developing understanding that RAAC does not necessarily visibly deteriorate before any collapse. However, as our recent article discusses, the potential structural implications of ageing RAAC are not a new discovery. Following a RAAC building component failure involving a flat roof where there was little warning of sudden collapse, the DfE and Local Government Association issued a letter to school building owners back in December 2018.  

The Standing Committee on Structural Safety/Collaborative Reporting for Safer Structures (CROSS) has been highlighting these issues for almost five years. These warnings were heeded, and indeed certain Scottish public sector risk managers have been honing a methodology to identify and address the risks of aging RAAC over the past 20 years.

While the press may focus on the disruption created by the closure of public facilities, these closures reflect a present reaction to the choice of construction materials made decades ago, in order to properly protect users of public spaces.

Risk management: considerations for councils

Risk management starts with gathering information about the nature and extent of any risk. This involves considering emerging information about the general nature and properties of ageing RAAC. It also requires action to locate RAAC, which may be in isolated areas within buildings.

Following identification of RAAC within the estate, assessment of the material in position by a suitably qualified expert will feed into an action plan for any specific location. However, given the profile of this issue, appropriate experts will currently be in demand.

An up to date knowledge of the fundamental differences between RAAC and conventional concrete is crucial. It is also important to note that an expert’s assessment may identify other challenges within the same building, or for any remedial work, including the presence of asbestos. Any action plan needs to also address other such risks. 

Such action is costly. The Building Safety Act 2022 includes provisions extending prescriptive periods for claims related to construction products, which apply north of the border. However, the extended period for action is 15 years, and in any event, RAAC was not defective when installed, and has simply come to the end of its life.

Scottish public sector risk managers should continue to adhere to the most up-to-date approach to RAAC, based on expert advice and guidance. Public safety is of the upmost importance.

Related item: RAAC and its impact upon construction professional indemnity claims

Read others items in Construction Brief - November 2023