Properties of EPS

Four retaining walls insulated with EPS expanded polystyrene airpop

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

Mechanical properties
  • Compressive stress @10% compression (kPa)

    EPS 7070

    EPS 100100

    EPS 150150

    EPS 200200

    EPS 250250

  • Compressive stress @1% strain (kPa)

    EPS 7020

    EPS 10045

    EPS 15070

    EPS 20090

    EPS 250100

  • Bending strength (kPa)

    EPS 70115

    EPS 100150

    EPS 150200

    EPS 200250

    EPS 250350

Moisture properties
  • Vapour resistivity (MNs/gm)

    EPS 70145

    EPS 100200

    EPS 150238

    EPS 200238

    EPS 250338

Thermal properties

  • Thermal Conductivity (λ) (W/mK at 10°C)

    EPS 700.038

    EPS 1000.036

    EPS 1500.035

    EPS 2000.034

    EPS 2500.034

SIPS panels using EPS expanded polystyrene airpop as insulation

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.

Standards

Pitched roof using EPS expanded polystyrene airpop as insulation

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