Extruded Polystyrene vs. Expanded Polystyrene (XPS vs. EPS) – What’s the Difference?

Extruded-vs-Expanded-Foam-XPS-EPS

What is Expanded Polystyrene or EPS Polystyrene Foam?

Expanded polystyrene (EPS), is produced from small beads of polystyrene that are fed into a mold. Heat or steam is then applied to the mould which expands the polystyrene beads and fuses them together. The expansion process causes the expanded foam to fuse together in irregular patterns that leave tiny spaces or irregular gaps in-between the foam cells.

Expanded Polystyrene Foam Cell Structure
Expanded Polystyrene Foam Cell Structure

Insulating Properties of EPS Foam

Inconsistent gaps between the EPS foam cells allows air & moisture to permeate throughout the foam, making EPS a less than ideal solution for moist environments.

Strength and Rigidity of EPS Foam

EPS foam cellular structures contain voids or spacing in-between the cells; these gaps form an irregular structure throughout the foam, making it less dense and rigid than extruded foams.

What is Extruded Polystyrene or XPS Polystyrene Foam?

Extruded Polystyrene (XPS), is manufactured via an extrusion process where plastic resin and other additives are combined and extruded through a die. The extruded foam then cools and expands into it’s final shape.

Extruded Polystyrene Foam Cell Structure
Extruded Polystyrene Foam Cell Structure

Insulating Properties of XPS Foam

XPS foam is considered to have a closed-cell structure wherein the cells are packed together tightly and have no voids or spacing between them. The tightly packed cells of XPS foam help prevent air & water ingress and make it more ideal for moist environments.

Strength and Rigidity of XPS Foam

XPS foam has a tightly packed closed-cell structure that makes it extremely rigid and strong, making it ideal for structural panels.

Why UltraBoard is Made with Extruded (XPS) Polystyrene

UltraBoard sheets are manufactured with an XPS foam core because of its rigidity and durability; as well as its resistance to moisture. When combining an XPS foam core with a plastic facer like our UltraBoard Classic product, you get an all-plastic board that is ideal for many interior environments and has a durability rating of 10 years.

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