The Building Research Establishment (BRE) has published fresh fire-safety test data, focusing on façade materials and insulation systems. The tests follow sustained regulatory scrutiny since the Grenfell Tower fire in 2017, which killed 72 people and triggered wholesale reviews of building codes in the UK and across Europe.
The BRE programme evaluated combustibility and flame-spread characteristics of external wall assemblies, including façade coatings, insulation boards, and composite cladding systems. Tests were conducted under BS 8414 and ISO 13785 protocols, which simulate large-scale fire exposure on multi-storey structures. According to the BRE, several material combinations that previously passed desktop assessments failed under full-scale conditions, particularly when cavity barriers or fire stops were omitted or incorrectly installed.
Implications for German and European building codes
Germany's Musterbauordnung (MBO) and state building regulations already restrict combustible materials in buildings above 22 metres. The BRE results are expected to tighten enforcement of testing requirements for insulation thickness over 100 mm, especially where phenolic foam or expanded polystyrene (EPS) is used. The German Institute for Building Technology (DIBt) has signalled it will cross-reference BRE data in upcoming revisions to approval notices for external thermal insulation composite systems (ETICS).
In Austria and Switzerland, the findings reinforce existing caution around combustible façade systems. Knauf and other insulation manufacturers are already marketing non-combustible mineral-wool alternatives in response to tighter fire-performance demands. The regulatory pressure on insulation is now coupled with proof-of-performance obligations that require third-party test certificates for each assembly variant.
Testing focus on multi-layer façade assemblies
The BRE tested more than 30 wall build-ups, isolating variables such as render type, primer adhesion, and cavity ventilation. Silicate-based coatings performed better than organic resin systems when exposed to radiant heat above 600°C. Significantly, the institution found that single-coat primer applications reduced flame spread by up to 40% compared to unprimed substrates, a finding relevant for renovation projects on historic façades.
The data has direct consequences for contractors specifying materials on multi-storey residential projects. Insurers and approval bodies are likely to demand BRE-certified test reports as standard evidence of compliance, raising procurement costs but reducing liability exposure. Façade contractors should verify that product datasheets reference the exact test standard and assembly configuration used on site.
The BRE has committed to quarterly updates of its fire-test database, with next results expected in October 2026. The focus will shift to rainscreen systems and ventilated façade cavities, areas where fire can spread rapidly if detailing is inadequate.
