Development of a Fire Safety Assessment Test for External Cladding Systems

Abstract

In the context of increasing façade fires, especially in the UK, where combustible cladding systems are approved for high-rise buildings, this study addresses concerns related to fire testing cladding systems. Key developments include:

1. Comprehensive Database of BS 8414 Tests: A database was compiled, analysing various cladding systems and their subsequent fire performance. It highlights certain systems' unrealistic construction methods, which aren’t replicated in real buildings. It also raises concerns around thermocouple criteria and placement relative to the fuel load. Test results were analysed to estimate the impact of changing the evaluation criteria.
2. Material Fingerprinting: A method for characterising cladding products was developed, using microscale combustion calorimetry and infrared spectroscopy to assess chemical composition and properties relating to fire performance.
3. RISC 501 Development: This study proposes a new fire test method and assessment criteria for external cladding systems, called RISC 501, which can be conducted alongside the existing BS 8414 test method, allowing conference with the BR 135 performance criteria. While BR 135 is focused on life safety, RISC 501 specifies enhanced performance criteria to focus on property protection. It incorporates revised requirements for the test construction, material characterisation, temperature criteria, and mechanical performance criteria. It also includes gas sampling methods to assess potential smoke toxicity produced by a burning cladding system.
4. Validation Tests: Validation tests confirm RISC 501's effectiveness in distinguishing between combustible and non-combustible cladding systems, offering a clearer performance differentiation compared to the BR 135 criteria. The proposed gas sampling method effectively distinguishes between combustible and non-combustible systems and provides insights into predicting the Fractional Effective Dose for incapacitation.

In summary, this study produces research to aid the development of a fire test and assessment for external cladding systems and then uses that research to develop RISC 501 – Fire Safety Assessment Test for External Cladding Systems.