3/3/2026
An assessment in lieu of testing allows fire performance to be determined using existing fire test evidence rather than carrying out a new physical fire test.
In the UK, this route is recognised in Approved Document B (Appendix B). Fire performance may be demonstrated through direct testing, design to recognised standards, or assessment based on relevant existing test data. It is this third route that is commonly referred to as an assessment in lieu of testing.
In practice, assessments are often used where testing every variation would be impractical — for example, where there are minor product modifications, system interfaces, or project time constraints. When properly justified, they can reduce cost, save time, and avoid unnecessary additional testing.
However, they are not shortcuts:
Assessments must be supported by robust, directly relevant and technically comparable evidence. Where extended application (EXAP) standards exist, they should be followed. If there is no applicable EXAP standard — or where performance classifications fall outside defined rules — assessment reports should be prepared in accordance with the principles of BS EN 15725, clearly identifying the fire test evidence relied upon.
Where assessment is the only appropriate route because the intended application is not covered by an extended application standard, best practice guidance is provided in the Passive Fire Protection Forum’s Guide to Undertaking Technical Assessments of the Fire Performance of Construction Products Based on Fire Test Evidence. The same principles referenced in paragraph B2 of Approved Document B should be applied.
Crucially, assessments should be undertaken by competent, appropriately accredited bodies, such as UKAS-accredited laboratories or notified bodies. Even small changes in construction detail can significantly affect fire performance, meaning technical judgement, transparency, and defined scope are essential.
With increasing regulatory scrutiny across the construction sector, the quality and credibility of fire assessments have never been more important.
At Efectis, our team provide independent, evidence-based fire assessments backed by more than 70 years of testing expertise. If you would like to discuss a project, our specialists would be pleased to help.
For more information, please contact Soukayna Azdad