Expanded polystyrene (EPS)

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Expanded Polystyrene (EPS) is a rigid, closed cell, thermoplastic produced from solid beads of polystyrene. It is polymerised from styrene monomer and contains a pentane blowing agent.

Each solid polystyrene bead contains small amounts of gas which expand when heated thus forming closed cells of EPS.  With a second heat treatment these beads can, using a mould, be moulded into large EPS blocks or specific customised shapes.

EPS should not be confused with XPS, Extruded Polystyrene.

Applications include wall, roof and floor insulation.


Walls, roofs and floors


Cost effective
Low thermal conductivity
Excellent compressive strength and durability

PIR = Superior thermal performance

Because of its superior thermal performance PIR insulation offers optimal insulation value meaning a thinner layer will achieve the same insulation properties.  This has other benefits, as using thicker insulation will mean a larger building footprint or smaller internal dimensions for a property.

The diagram shows the typical thicknesses of different wall insulation materials needed to achieve an R value of 4.5.