EPS vs XPS: Why EPS is Better

eps vs xps chart
Expanded Polystyrene (EPS) has finally met its match in extruded polystyrene (XPS). However, those who would like to do an objective comparison between the two often insist that EPS is the better option. To begin with, both materials share a similarity in the sense that they are both created with polystyrene resins, and the result is Geofoam. In addition, both are closed-cell and rigid forms of insulation. The difference comes in as XPS is an extruded sheet whereas EPS comprises numerous beads that have been molded or cut into specific shapes and sizes.

A Closer Look at the Differences Between EPS and XPS: Manufacturing

The manufacturing process necessary to create EPS is different from that used for XPS. The Expanded Polystyrene blowing agent exits the beads quite quickly, resulting in thousands of diminutive cells laden with air. Alternatively, the XPS blowing agent remains embedded within the material for several years, decreasing the potential for air to move through the material as desired. This difference results in XPS having a comparably low moisture rate versus EPS.

What About the R-value Retention?

Expanded Polystyrene insulation has a higher R-value retention as compared to Extruded Polystyrene. While Extruded Polystyrene is characterized by off gassing, the gasses eventually escape, meaning the initially high R-value gradually decreases. Insulation R-value is lost in unison with the gas escape. In short, EPS outperforms XPS in the context of R-value across the long term, ensuring the structure in question is climate controlled exactly as desired.

The Management of Moisture

When people search the web for “insulation companies near me”, they key in on those that provide materials that are elite in terms of moisture management. EPS has comparably rigid insulation that is closed cell with an elevated tolerance that ensures moisture is resisted. In fact, field studies show EPS absorbs less moisture than anticipated.

Merely one-half of a percent is absorbed by EPS in a 15-year span, meaning it really is the best insulation for attic and also the best insulation for walls. Furthermore, when moisture moves into tiny cavities, EPS has a superior ability to expel that moisture.

Add in the fact that EPS has drying potential and XPS does not have such potential and there is even more reason to choose EPS. Drying potential is particularly important in the context of thermal insulation as it helps ensure the optimal thermal resistance, also known as R-value, is maintained amidst extensive exposure to moisture and other threats.

Can Both be Recycled?

Expanded Polystyrene (EPS) is advantageous as it is fully recyclable. Recycling centers throughout the country are more than willing to recycle EPS. Though few know it, in excess of 200 collections centers for EPS are available throughout the country. In fact, more than 100 million pounds of EPS are recycled on a yearly basis.

Cost in the Context of R-value

EPS is more cost-efficient than XPS, running between 10% – 30% less per R-value equivalent as well as compressive strength.


Customization is quickly becoming the name of the game in the construction industry. Customers and building professionals alike are leaning toward sheets outside of the regular 4′ x 8′. EPS is better in terms of customization, allowing for all different shapes, sizes and thicknesses to be made. EPS has the potential to be made with a thickness upwards of 48″, allowing it to be used for crawl spaces, pre-cast concrete, wall furring, foundations, under a slab, sheathing, and many other applications. In contrast, XPS has a maximum thickness of 3″ to 4″. Furthermore, EPS can elevate to R-209 whereas XPS is capped at R-15. Add in the fact that lamination can be added to EPS and there is even more reason to choose this material.

Bonding Capability

EPS foam features a surface that allows for timely and thorough bonding. Alternatively, XPS bonding is much more challenging. Ask anyone who works in the Structural Insulated Panels and Exterior Insulated Finish System industries about these two materials and you will find the overwhelming majority favor EPS’s elite bonding capability. Furthermore, the packaging industry relies on EPS as its superior component bonding proves quite helpful.

The Impact on the Environment

Expanded Polystyrene is superior to Extruded Polystyrene in the context of the environment as EPS has never and likely will never be made with HCFCs that compromise the environment. Furthermore, those looking to preserve our fragile planet favor EPS as it does not use any type of dye. Add in the fact that EPS can be constructed with recycled content and there is even more reason to favor EPS over XPS.

In contrast, XPS typically contains dyes along with branding elements. In terms of the use of recycled materials, XPS is comparably inconsistent. The specific XPS product and manufacturer determines the level of recycled material used.

The Issue of Durability

EPS can be constructed in several different densities with the potential to reach a compressive strength upwards of a whopping 8,640 pounds/feet along with an impressive 10,800 pounds/feet of flexural strength. Though EPS is 98% air and uber-light, it is quite strong. Add in the fact that EPS is superior to XPS insulation R-value thanks to its laminated poly facer application to board for enhanced durability and impact resistance and there is even more reason to choose EPS.

Interested in learning more about Ploy Molding’s alternative product to XPS? Our POLY RITE Expanded Polystyrene product can be your project’s next geofoam solution.

Share the Post:

Related Posts