Properties of EPS
For construction applications the properties of EPS are determined according to a set of harmonised European Standards or BS ENs. BS EN 13163 is the base standard for EPS (see below) www.bsi-global.co.uk
The low, stable, thermal conductivity of EPS is the reason for its important use in reducing the carbon dioxide (CO2) emissions in our buildings. This vital property is declared as a 90/90 value defined in BS EN 13163 to represent 90% of production with a statistical certainty of 90%.
Other properties, for example compressive strength or tensile strength, can be declared at a variety of levels independently of each other. However in reality the number of standard products is relatively small and a typical range of properties is shown in the table below:
Typical properties of white EPS
Compressive stress @10% compression (kPa)
Compressive stress @1% strain (kPa)
Bending strength (kPa)
Vapour resistivity (MNs/gm)
Thermal Conductivity (λ) (W/mK at 10°C)
The table gives typical properties for the traditional white EPS. A detailed explanation of all properties can be found in The White Book published on line at www.eumeps.org
In recent years developments have taken place to introduce a grey product which has the advantage of a lower thermal conductivity giving a 20% improvement in thermal resistance.
A thermal conductivity of 0.030W/mK can be achieved for EPS 70 or 100.
BS EN 13163:2008
Thermal insulation products for buildings. Factory made products of expanded polystyrene (EPS). Specification
BS EN 13499:2003
Thermal insulation products for buildings. External insulation composite systems (ETICS) based on expanded polystyrene. Specification
BS EN 14933:2007
Thermal insulation and light weight fill products for civil engineering applications. Factory made products of expanded polystyrene (EPS). Specification
BS EN 13172:2008
Thermal insulation products. Evaluation of conformity
Guide to fire characteristics and fire performance of expanded polystyrene materials (EPS and XPS) used in building applications