Data from 252 commercial fire tests in Poland (KRESNIK) was analysed (tests of 90 façade materials, some were tested three times, some fewer if failed). Façade materials were tested to the standardised Polish PN-B-02867 test, in which a 20 kg wood crib is the fire source, 50 mm from the façade, with a 2 m/s airflow towards the façade. The material is mounted vertically, as it would be on a building, approx. 2m x 2m, depending on panel size. The authors classified the façade materials as 24 ETICs (external thermal insulating composite materials: a layer of insulation fixed to a substrate with a thin layer of external render), 21 sandwich panels (insulation between two substrates, usually metal), 38 rainscreen facades (multiple layers of insulation, vapour and weather control layers, usually with a cavity) and 7 other. None of the ETICs or sandwich panels failed the test, whereas 45% of rainscreens failed (pinfa comment: probably companies only presented materials expected to pass). The authors conclude that a cavity in the panels significantly impacts fire performance, as can different material layers. General categories of materials correlated to pass/fail, with (predictably) non-combustible (Euroclass A2) materials not failing. Flame retardant ACP (aluminium composite panel) and HPL (high pressure laminates) showed significant fail rates, but this could not be predicted by total fuel content nor by conductive resistance.
“KRESNIK: A top-down, statistical approach to understand the fire performance of building facades using standard test data”, M. Bonner et al., Building and Environment 169 (2020) 106540 https://doi.org/10.1016/j.buildenv.2019.106540