Marcello Hirschler summarises updates of façade requirements in the 2021 US IBC (International Building Code). He underlines that the NFPA 285 test in place since the 1980’s has shown to ensure fire safety, in that the US has had zero fatalities in cladding fires where systems have passed this test. NFPA 285 is a full-scale test, using a complete wall assembly at least 5m high x 4m wide, including a mock-up room with a window opening in the wall, and a complete wall assembly with cladding, attachments, joints, etc. The primary aim is to ensure that fire does not spread upwards to the next storey. Test criteria include vertical and lateral flame spread, fire penetration, temperatures reached and propagation between compartments. It is recognised that testing of materials is insufficient, and that fire testing in the full-scale structure is essential. However, minor modifications from tested assemblies are accepted, subject to expert judgement that this will not significantly modify overall fire performance. In addition to this full-scale test, further specific tests are defined for different types of building material, such as barriers to prevent fire penetration and light-transmitting wall panels.