Mind the Gap?

Discover how XPS Insulation Outperforms EPS Insulation​

Image showing a pile of extruded polystyrene insulation panels.
Image showing a pile of extruded polystyrene insulation panels.


There are two types of polystyrene-based insulation on the market: extruded polystyrene (XPS) and expanded polystyrene (EPS). At first glance, one might think that the two are rather similar: both are lightweight rigid panels that are easy to handle and install. However, the similarities end there. For that matter, some EPS manufacturers claim that their product is not only visually similar to XPS, but also more efficient. Yet when it comes to choosing insulation, one look at the most important criteria is enough to realize that XPS is technically superior to EPS.

See for yourself in this bulletin the differences between these two insulation materials:

  • More EPS is needed to achieve the same insulation capacity as XPS.
  • The R-value per inch of XPS is always greater than that of EPS, regardless of average temperature.
  • The R-value superiority of XPS over that of EPS increases even more over time.
  • The risk of water absorption is lower with XPS than with EPS.
  • Freeze-thaw cycles affect the thermal resistance of EPS.

In the end, thanks to its very dense nature, XPS will always keep its thermal performance, no matter if it is dry or if it absorbs a little water. On the other hand, EPS will immediately be affected by water and moisture, which will have a direct impact on its R-value, and will never return to its initial performance over time.