RAAC (Reinforced Autoclaved Aerated Concrete) is a lightweight form of precast concrete, widely used in the UK between the 1950s and mid-1990s in roofs, ceilings, walls, mansards, and occasionally floors. It's often labelled simply "AC Concrete" on older building drawings, which has made it easy to overlook.
Its lightweight, bubble-filled structure, which can account for well over half its volume, gives RAAC minimal compressive strength compared to traditional concrete, and its reinforcement is typically non-bonded. Combined with limited resistance to damage, this means RAAC planks can fail with surprisingly little warning, particularly where they've been loaded, drilled into, suspended from, or exposed to water ingress over time.
Where RAAC is identified in a commercial or public building, most local authorities and organisations move quickly toward remediation, and in the most serious cases, closure or demolition, given the disruption and risk involved in leaving it unaddressed.
RAAC planks don't interlock and work independently. Rooftop plant, re-roofing materials, or bearings that fall short of minimum recommendations can be enough to trigger failure.
Services, fixtures, and fittings hung directly from RAAC planks place stress the material was never designed to carry, sometimes with catastrophic results.
The air voids that make RAAC lightweight also make it absorbent. Water ingress, especially through coated or painted planks, is a well-documented cause of structural failure.
Cutting or altering planks for penetrations, services, or plant installations is one of the most significant and avoidable causes of RAAC failure on site.
RAAC BRAC is the UK's primary supplier of RAAC remedial solutions, engineer-backed and built on a 25-year design life. Their component-based system was originally developed for live retail environments, where a simple, cost-effective, and minimally disruptive fix was needed to keep trade running while protecting colleagues and customers.
Four primary kit types cover the large majority of RAAC scenarios, whether RAAC is present as a roof, or has been adapted into a floor, with bespoke solutions available for the rest. Components are engineered, surveyed, and specified by RAAC BRAC's partner engineers, then manufactured in Yorkshire under licence.
Cole Todd Fabrication provides the hands-on steel fabrication and site-based installation skill that RAAC BRAC's kits are built around, fitting components efficiently and to specification across commercial and public sites.
RAAC BRAC handle the survey, engineering, and component supply, we handle the on-site steel fabrication and installation. Getting a quote is straightforward:
Head to raacbrac.com and get in touch through their contact form with details of your site.
RAAC BRAC will complete a survey and specification for the project.
Once complete, as a RAAC BRAC approved installer, we'll be in touch to arrange installation.
