Expanded polystyrene and fire safety Recent tests have confirmed the fire retardant properties of StyFRene expanded polystyrene (EPS) FR grade thermal insulating board. The key finding of the tests is that, in a fire, EPS does not support the spread of flames. Architects and specifiers can now confidently incorporate EPS in designing energy-efficient and cost-effective building solutions, by using StyFRene.The tests, commissioned by EPSASA, were conducted by Firelab cc, based on the premises of the Council for Scientific and Industrial Research (CSIR) in Pretoria. They were carried out in line with the protocol defined in SANS 428:2006 – “Fire performance classification of thermal insulated building envelope systems”.

SANS 428 covers the fire safety evaluation requirements for thermal insulated building envelopes, such as under-roof and side-cladding insulating materials, liners, insulated wall and roof panels, insulated ceilings and insulated wall and ceiling coating systems. This testing protocol requires that large-scale fire testing of thermal insulation materials (SANS 10177:11) must be done in a facility that simulates the real-world, end-use conditions in which the product is typically installed.

EPS StyFRene boards of 80mm thickness, and without any facing material, were used in all the tests. EPSASA generally recommends 80mm to 100mm EPS board for ceiling and roof applications, depending on relevant climatic conditions. Continuous improvements in FR grade EPS, in the polystyrene raw material, and fire retardant properties and processing, have now produced a material that is classified as fire safe. The Firelab assessment entailed a series of three tests to evaluate the material’s fire propagation properties in different applications: under-roof without a sprinkler extinguishing system; under-roof with a fixed sprinkler system using slow response sprinkler heads; and in vertical side-cladding applications.

The test results show that although EPS StyFRene does deform and melt in proximity to fire, it does not actually catch alight: the material simply disintegrates into small snowflake-like fragments.

The test report concludes that: “From a fire safety point of view, the FR grade EPS thermal insulation system, as tested under specific test conditions, may be used as part of the thermal insulated building envelope in all industrial and commercial buildings as an under-roof and side-cladding insulation material, both with or without sprinklers.”

It is nonetheless important to note that these test results do not relate to fire resistance, which entails different testing criteria and testing methods. Furthermore, factors such as adequate roof ventilation and/or sprinkler protection should be considered in individual installations, taking account of the specific wall and roof configurations, to ensure the fire-safe design of any building, according to SANS 10400:T.Suppliers should be asked to verify their products’ conformity to the test materials.