Overview

Reinforced Autoclaved Aerated Concrete (RAAC) is a lightweight form of concrete, used in structural planks within floors, walls and roofs (both flat and pitched). The Standing Committee on Structural Safety (SCOSS) has noted that: ‘Although called “concrete”, (RAAC) is very different from traditional concrete and, because of the way in which it was made, much weaker. The useful life of such panels has been estimated to be around 30 years’ (SCOSS Alert, May 2019). If RAAC is suspected, a specialist Structural Engineer should be appointed. If RAAC is confirmed, the specialist should undertake a detailed assessment and prepare a management and remediation strategy.

RAAC was used in buildings between mid-1930s and mid-1990s, so any buildings constructed, added to, or modified between these periods should be inspected.

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Inspection; Stage 1 of the inspection process as advised by DfE guidance doc ‘Reinforced Autoclaved Aerated Concrete (RAAC) Identification Guidance; September 2023’ will be completed.

The works included for within a Stage 1 Inspection will comprise;

Information Collection;

Information and data will be collated from the client both prior to site visit and as part of an initial site-based desktop assessment. This information will include, but is not limited to, collation and review of building plans, construction and maintenance information and data for all buildings on site constructed or added to/altered between mid-1930s and mid-1990s.

Initial Assessment;

A detailed inspection of each building that incorporates solid floors, walls or roof elements within the structure, both to the original building and within later extensions and alterations. This process will incorporate information and data gathered from the initial desktop study, along with inspection to the building fabric as far as reasonably practicable. Access will be gained where possible into floor and wall voids, ceiling voids above suspended ceilings and fixed plasterboard suspended ceilings if necessary, loft and roof voids, and externally.

It may be necessary to remove small parts of asbestos containing material to investigate above or behind this. With our team of in-house Asbestos Specialists we are in a unique position that allows us to do this holistically all as part of the same inspection with minimal disruption and without 3rd party involvement.

The purpose of the Stage 1 Inspection is to identify whether RAAC materials are present within the building fabric, allowing for progress to Stage 2 if applicable.

Reporting;

A report will be provided for each building which will include;

• An overview of RAAC and the guidance
• Method of Inspection
• Results
• Marked up floor plans showing location of RAAC and, if visible, the size and number of planks and direction of span
• Guidance and advice on next stages if required

What next?

If no RAAC is located within this initial Stage 1 Inspection process, then no further action is required.

If RAAC is identified then guidance will be given on how to proceed with Stage 2; detailed Structural Inspection, Assessment, and Management and Remediation Strategy.