Adam Boumnaia from product testing laboratory Attain RTC details the exhaustive methods used to help translate fire test results into reliable, evidence-based applications under the UK’s evolving standards framework.
In recent years, the UK construction sector has transitioned from historic BN British Standards to European (EN) test methods and classification systems as part of a wider effort to strengthen fire performance standards and legislation. This transition has created a more structured framework for demonstrating performance, with clearer links between what is tested in the laboratory and what is ultimately installed on site. True assurance depends not only on how products are tested, but also on how the results are interpreted and the extent to which those results can legitimately be applied.
Transitioning from single test results to defined applications
Historically, fire testing has often been conducted as a one-off exercise: build a sample system, test it, and record the result. The challenge arose when applying that result to products of different sizes or configurations, as the limits of application were not always clearly defined.
The transition from historic BS 476 test methods to BS EN test standards and classification systems addresses this issue. It incorporates rules for practical application directly into the standards framework, enabling performance to be more clearly defined, traceable, and consistently applied.
The result of a fire resistance test, such as BS EN 1364-1 (which replaces BS 476-22), is used to classify the tested system in accordance with BS EN 13501-2. For example, a classification of EI 240 indicates 240 minutes of integrity and insulation fire resistance. However, the classification itself is only the starting point.
Direct Field of Application (DIAP)
DIAP rules are incorporated directly into the test standard. They define specific, limited variations that are automatically covered by the test result without the need for further assessment. Depending on the relevant standard and construction type, DIAP may permit defined modifications such as reductions in size, increases in certain component thicknesses, or other dimensional changes specified within the test standard.
DIAP provides a clearly defined baseline scope of application, ensuring that every fire test result is accompanied by an inherent and published range of permitted use.
Extended Application (EXAP)
EXAP standards provide a structured, rules-based method for extending fire test results using recognised technical principles. EXAP is carried out in accordance with the relevant EXAP standard, which may be supported by:
- EN extended application standards
- EN product standards
- European Assessment Documents (EADs)
- Relevant European Commission Decisions or delegated acts
- EN 13238 (conditioning procedures)
- CEN/TS 15117 and other sector-specific technical specifications.
The process typically follows one of several recognised methods:
- Direct reference to product technical specifications where extension rules are already defined
- Relationship-based assessment, demonstrating how performance varies with defined parameters
- Experimental or empirical programmes, using additional test evidence to map performance changes
- Recognised calculation methods where validated models are available.
The objective is to ensure that any extension remains technically justified and consistent with established European testing methodology.
Navigating the pathway from test to classification
The final classification report records not only the fire resistance performance, but also the permitted field of application derived through DIAP and EXAP.
Avoiding misinformation
While BS EN 1364 and BS 476 are fundamentally different test standards, there is currently insufficient publicly available evidence to support broad conclusions regarding how products previously tested to BS 476 will perform when assessed using harmonised European test methods.
The transition should therefore be approached on the basis of evidence rather than assumption. It would be inappropriate to suggest that products achieving a particular level of performance under BS 476 will automatically achieve an equivalent classification under BS EN 1364 without supporting test data. Equally, claims that such performance cannot be achieved should also be supported by robust evidence.
The most reliable approach is producing representative test evidence to demonstrate performance, testing and classification exist to provide objective proof of performance. Discussions surrounding the transition should be informed by data and technical evidence rather than speculation.
Adam Boumnaia is general manager at Attain RTC