UKAS accreditation in NDT — what it means
UKAS accreditation is the UK's mark of laboratory and inspection-body competence. Here is what it means in NDT and concrete testing, and why it matters.
UKAS — the United Kingdom Accreditation Service — is the body that accredits laboratories, inspection bodies, and certification bodies in the UK. UKAS accreditation is the recognised mark that a body works to internationally agreed standards of competence, impartiality, and quality. For non-destructive testing and concrete testing, UKAS accreditation is the difference between a defensible result and an unverified opinion.
What UKAS does
UKAS is the UK’s national accreditation body, recognised by government and signatory to international mutual-recognition agreements. It accredits organisations against international standards — for laboratories, that is ISO/IEC 17025; for inspection bodies, ISO/IEC 17020; for certification bodies, ISO/IEC 17065 or ISO/IEC 17021-1.
Accreditation is a peer-reviewed assessment of an organisation’s:
- Technical competence in the methods it claims to deliver.
- Quality management system.
- Impartiality and integrity.
- Traceability of its measurements.
UKAS accreditation is granted only after on-site assessment by technical experts. It is renewed through scheduled re-assessment and ongoing surveillance.
Where UKAS matters in NDT
UKAS accreditation in NDT and concrete testing typically appears in three forms:
Laboratory testing of cores. When concrete cores are extracted from a structure and tested for compressive strength, the laboratory doing the testing should be UKAS-accredited for the relevant method (BS EN 12504-1 for sample preparation, BS EN 12390-3 for compressive testing, or equivalent). UKAS-accredited laboratories provide a certificate of test that is defensible in dispute work and recognised by structural engineers, regulators, and insurers.
On-site NDT inspection. Some NDT inspection bodies hold UKAS accreditation under ISO/IEC 17020 for specific inspection scopes. This is more common in industrial NDT (welding, pressure equipment) than in construction concrete work, but where it applies, it provides a similar defensibility.
Calibration. Equipment used in NDT is often calibrated against standards traceable to UKAS-accredited calibration laboratories. The traceability chain — equipment to working standard to national standard to international standard — is what gives field measurements their defensibility.
Why it matters
A UKAS-accredited test certificate is the kind of evidence that:
- Insurers accept as proof of as-built strength on completed work.
- Structural engineers can rely on for assessment calculations.
- Regulators accept for compliance verification.
- Courts accept in dispute resolution.
A non-accredited test result is, by contrast, an opinion. It may be perfectly accurate, but it lacks the institutional backing that lets a third party rely on it without further verification.
For most concrete testing on UK construction projects — particularly any work that may end up in dispute, regulatory review, or formal engineering assessment — UKAS-accredited laboratory testing is the appropriate standard.
What it doesn’t cover
UKAS accreditation is method-specific and scope-specific. A laboratory may be accredited for compressive strength testing of cores but not for some less common method. The accreditation certificate lists the specific tests covered.
UKAS accreditation also does not extend to interpretation. A laboratory provides an accredited test result; the engineer interprets that result in the context of the structure. The interpretation lies outside the laboratory’s accreditation.
For on-site NDT methods where accreditation is less common (rebound hammer, pull-out testing, GPR), the relevant defensibility comes from:
- Method standards (BS EN 12504 series, BS 1881).
- Manufacturer calibration.
- Operator certification (PCN, EuroGPR).
- Documented method statements and quality systems at company level.
These are not substitutes for UKAS accreditation but are the appropriate defensibility chain where UKAS does not directly apply.
How to verify
UKAS publishes its register of accredited bodies. Verification takes a minute:
- Get the laboratory’s name and UKAS testing laboratory number.
- Check the UKAS schedule on the public register.
- Confirm the relevant test methods are within the accredited scope.
Test certificates from UKAS-accredited laboratories carry the UKAS logo and accreditation number on every page. A laboratory claiming UKAS accreditation but unable to produce a current certificate should be questioned.
Practical advice for commissioning
When commissioning NDT work that involves laboratory testing:
- Specify UKAS accreditation explicitly. “UKAS-accredited compressive strength testing to BS EN 12390-3” leaves no ambiguity.
- Confirm the lab’s accreditation scope covers the methods needed. Don’t assume.
- Receive the test certificates with the relevant accreditation logos and numbers.
- Keep certificates on file. They are part of the project’s quality record and may be relied on for years.
For on-site NDT where laboratory accreditation does not apply, the equivalent is a documented quality system, calibrated equipment, and qualified operators. Ask about all three.
The bigger picture
UKAS accreditation is a proxy for a much wider quality discipline — the willingness of an organisation to subject itself to external scrutiny, document its methods, and stand behind its results. Organisations that invest in UKAS accreditation tend to invest in the wider quality systems that support good work; organisations that do not, tend not to.
For any project where the test data will be relied upon for engineering, contractual, or regulatory purposes, UKAS-accredited testing is the appropriate baseline. The marginal cost over non-accredited testing is small; the defensibility it adds is significant.