• Cornices from polystyrene EPS
  • polystyrene in houses ceilings
  • storage of polystyrene

Expanded Polystyrene or EPS is a durable, flexible and innovative material used in a wide range of industries that care about their carbon footprint.


Literally translated, polystyrene is "polymerised styrene". The expandable form (known as EPS) is initially produced as small beads containing a blowing agent. The beads expand when treated with steam, forming a lightweight "prefoam" of the required density.

These prefoamed beads are processed in a mould to form large blocks that are then cut into sheets or other shapes. Alternatively, for high volume products, the beads are moulded into their final product form in individual moulds.


    • Cold storage insulation: floors, walls, ceilings, foundations.
  • Lagging: pipes, tanks, vessels, valves and ductwork insulation.
  • Industrial and domestic insulation: floors, walls, ceilings and roofs.
  • Building and construction: concrete fill and for expansion joints.
  • Insulated panels and door manufacture: core insulating material.
  • Protective packaging: for maintaining the temperature of perishables and protecting food stuff or the protection of fragile goods such as electronics.


Chemical Resistance
EPS is resistant to: brine, fresh water, weak mineral acids, strong mineral acids (except concentrated nitric), weak alkalis, strong alkalis, most vegetable oils. Non-resistant to: mineral oils, chlorinated hydrocarbons, petrol, benzine, esters and ketones.

Burning Characteristics
EPS is a combustible material. The amount of heat liberated by EPS undergoing combustion is very small and if this is dissipated then sustained ignition is unlikely. The 'FR' grades are treated with a fire retardant which causes the material to shrink away from a source of ignition without burning if exposed for a short period, but burns if kept in contact with the flame for a longer period.

Flame Retardant Grade (FR)
Flame retardant polystyrene (FR Grade) is available in all densities. Surface fire index results according to SABS 0177, part III yield the following results: Spread of flame index 4,4. Heat contribution index 0,9. Smoke emission index 9,9. Surface fire index 4,7. Class 5.

Material Properties of EPS 


UnitEPS 15EPS 20EPS 30
K value Thermal conductivityW/m.K0,0400,0380,036
Water-Vapour Diffusion Resistance Value-203060
Compression strength at 10% deformationkPa60100165
Short term compression strengthkPa80120210
Long term compression strengthkPa203050
Shear strengthkPa190270460
Tensile strengthkPa200280440
Water absorption fully-submerged after 7 days% volume1,70,60,5
Water absorption fully-submerged after 1 year% volume5,04,03,0
Linear expansion co-efficientM/m7.10-57.10-57.10-5
Co-efficient of friction 0,50,50,5
Heat capacityJ/kg K150015001500
Temperature range°C-110/+70-110/+70-110/+70
Limited exposure maximum temperature°C+110+110+110
Youngs moduluskPa4000600010000