‘Widely used polystyrene insulation system shown to be ‘similar’ to Grenfell-style cladding in Australian fire test’ — INCA responds to recent test report.

INCA Ltd are aware of a recent fire test reported by Commonwealth Scientific and Industrial Research Organisation (CSIRO) on behalf of Victoria Building Authority, Australia (Referenced test report ‘EP205417 revision D, dated 29th September 2020). The report considers the performance of a thin coat render system applied onto EPS insulation when installed on to a timber framed wall structure. The report concluded that EPS render systems can pose a similar fire risk to polyethylene core ACM systems, with the system failing to meet the criteria of BR 135 when tested in accordance with BS 8414-2. It also highlighted an additional risk of downward fire spread due to pooling fires initiated by molten EPS.

Following a thorough review of the report, INCA Ltd concluded that the design of the EPS system tested, notably, the absence of fire barriers, the wall construction selected for the test and the resulting conclusions stated in the above report are in no way representative of EPS based external wall insulation systems (specified historically pre-December 2018) by INCA members for use on multi-storey buildings in the UK. Prior to the December 2018 amendment to Legislation, in the UK EPS systems used on these buildings types must demonstrate compliance with the relevant Building Regulations and meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2. To demonstrate this compliance, the wall structure is invariably constructed in light weight steel and sheathed with a fire-resistant board; very different to that used in the CSIRO fire test. The systems are also designed with cavity barriers at floor slab levels to prevent fire spread, this is formed by the use a continuous non-combustible insulation in place of the EPS and, and a secondary barrier within the drained cavity zone directly behind the non-combustible insulation band. This is very different to the system tested by CSIRO which does not use cavity barriers, and this is referenced within their report as a notable difference from the system tested to those marketed and sold in the EU and UK.

INCA system holders hold a wealth of BS 8414-1 & 2 test reports demonstrating that correctly designed and specified EPS systems can comply with the criteria of BR 135 and therefore the relevant Building Regulations at the time of installation. To provide further reassurance on the performance of these systems, INCA members worked in partnership with the Building Research Establishment (BRE) in 2018 to release summary details of tested systems on their website for any stakeholders to access.