Experimental evaluation reveals substantial performance variability in Single Burning Item tests of polystyrene insulation, highlighting limitations of standard Euroclass fire ratings.
Key Points
To assess specimen-level and campaign-to-campaign variability in standard Single Burning Item reaction-to-fire testing for expanded-polystyrene external thermal insulation composite systems.
Conducted 23 Single Burning Item tests (EN 13823) on nominally equivalent expanded-polystyrene external thermal insulation composite systems across two campaigns 2.5 years apart in a single notified laboratory.
Evaluated the fire growth rate index, lateral flame spread, smoke production, and physical behaviors such as collapse and detachment across different editions of the test standard.
Coefficients of variation between nominally identical specimens ranged from 2% to 87%, with individual specimens from the same product spanning the Euroclass B and C boundaries.
Nominally equivalent assemblies in the second campaign exhibited mean fire growth rate indices 3.7 to 7.0 times higher than in the first campaign, alongside lateral flame spread in 7 of 8 tests.
One assembly achieved an s1 smoke rating with a mean smoke production of 0.4 m², despite two of its three tested specimens exceeding the classification threshold.