For a RAAC survey in Derry City, NDTScan brings something no general scanning contractor can: hands-on experience of identifying and analysing reinforced autoclaved aerated concrete across the UK, in schools, hospitals, housing, public buildings and commercial estates. Derry City and Strabane has its share of the roofs and floors built with these planks between the late 1950s and the mid 1990s, and most have never been properly surveyed.
The published RAAC lists cover education and NHS estates, and none of them names a Derry City building. NDTScan treats that as an absence of surveys rather than an absence of RAAC. Planks of this kind were installed across Derry City and Strabane from the late 1950s to the mid 1990s in public buildings, housing, leisure centres and commercial units, and the owner of a flat-roofed building of that age has no way of knowing without an identification survey.
The method NDTScan uses in Derry City is the one it uses everywhere: identify first, then assess. Ground penetrating radar reads the plank's internal structure without cutting into it, distinguishing RAAC from the dense precast, hollowcore and timber it is often mistaken for. Every confirmed plank is then inspected for the defects that matter, cracking, deflection, short bearing, water damage, corrosion and earlier repairs, and classified in line with IStructE guidance. The Derry City owner receives a plank-level record, not a general opinion.
NDTScan's advice to Derry City owners is consistent: survey before you decide. A RAAC roof that has been identified and assessed plank by plank can be managed, propped, strengthened or replaced on evidence. One that has only been glanced at will be closed, propped or replaced on fear, and that is where budgets go. The survey is the smallest cost in the chain.
Scan before you repair. That is the standing advice for every Derry City client, and the reason NDTScan reports what the concrete contains before anyone specifies what to do about it.
Services Available in Derry City
- RAAC Identification Survey GPR based, plank by plank identification of reinforced autoclaved aerated concrete in roofs, floors and walls across Derry City. Confirms what the element is made of without opening it up, and records plank widths, reinforcement and bearing details as evidence.
- RAAC Condition Assessment Plank level inspection of confirmed RAAC for cracking, deflection, bearing length, water ingress, corrosion and previous repairs, classified in line with IStructE guidance. Reported so a Derry City and Strabane engineer or estates team can act on it directly.
- RAAC Management and Reinspection Monitoring regimes, reinspection intervals and management plans for RAAC that is being kept in service, plus expert input where a Derry City owner needs an independent second opinion on a survey or a remediation proposal.
RAAC in and around Derry City
Typical Derry City instructions: RAAC identification in schools, halls, clinics and council buildings built between 1955 and 1995; plank by plank condition assessment of confirmed RAAC roofs and floors; risk classification in line with IStructE guidance to support decisions on closure, propping or continued use; reinspection and monitoring of managed RAAC; and independent review of surveys and remediation proposals for Derry City and Strabane owners and their insurers. NDTScan covers Derry City from Oxford in the same way it covers the rest of Northern Ireland.
NDTScan also provides RAAC surveys in Strabane, Culmore and Eglinton and the rest of Derry City and Strabane. The rest of the region is covered from the Northern Ireland RAAC surveys page, and the service itself is described on the RAAC surveys page.
About NDTScan
NDTScan is a specialist non-destructive testing company based in Oxford and led by Neil Smuts, author of The RAAC Book. It is the UK's specialist in the identification and analysis of reinforced autoclaved aerated concrete, and a Level 4 UKCSS Operator, the first in the UK to achieve that certification. RAAC surveys in Derry City sit alongside the company's concrete scanning and structural condition survey work, and every report is written to a standard suitable for engineering acceptance, insurers and dispute work.