Expanded Polystyrene vs. Extruded Polystyrene



The varied manufacturing procedures used to make Expanded Polystyrene and Extruded Polystyrene insulation can significantly impact their long-term effectiveness. It’s vital to remember that the variances can cause a structure to fail to work as intended.

Polystyrene is a synthetic aromatic polymer created from monomer styrene, generated from benzene and ethylene petroleum products. Polystyrene comes in two forms: foamed and solid. Polystyrene is a colorless, transparent thermoplastic that is often used to manufacture foam board or beadboard insulation and loose-fill insulation made out of tiny polystyrene beads. Air makes up 95-98% of polystyrene foams. Because polystyrene foams are good thermal insulators, they’re commonly utilized in building insulation materials, including insulating concrete forms and structural insulated panel construction systems.


Expanded Polystyrene(EPS)

Expanded polystyrene (EPS) is a closed-cell foam that is hard and durable. Around two-thirds of expanded polystyrene demand comes from the building and construction industry. It’s used to keep (cavity) walls, roofs, and concrete floors warm. Expanded polystyrene can be utilized in various applications due to its technical features such as low weight, rigidity, and formability, such as trays, plates, and fish boxes.

Extruded Polystyrene(XPS)

XPS (extruded polystyrene) is a thermoplastic polymer as well. Extruded polystyrene has a closed-cell structure, is often stronger, and has better mechanical properties than EPS. It is also, in theory, more expensive. It has a density range of 28–45 kg/m3. Because XPS is made from the same raw ingredients as EPS, it also contains crude oil. Extruded polystyrene is made similar to expanded polystyrene, with just minor differences.

Let us now explore the difference between EPS and XPS.

Manufacturing Process

Creating EPS requires a different manufacturing technique than creating XPS. The Expanded Polystyrene blowing agent quickly escapes the beads, resulting in hundreds of tiny air-filled cells. On the other hand, the XPS blowing agent remains embedded in the material for several years, reducing the capacity for air to pass through it as desired. As a result of this difference, XPS has a lower moisture rate than EPS.


Compared to Extruded Polystyrene insulation, Expanded Polystyrene insulation retains a higher R-value. While off-gassing is a characteristic of Extruded Polystyrene, the gases eventually escape, resulting in a progressive drop in the R-value. The R-value of the insulation is reduced in tandem with the gas release. In short, EPS beats XPS in terms of R-value over time, ensuring that the structure in question is properly climate-managed.

Moisture Management

When individuals look for “insulation firms near me” on the internet, they look for organizations that offer superior materials in terms of moisture control. EPS is stiff, closed-cell insulation with a high moisture tolerance that assures moisture resistance. In reality, field tests have revealed that EPS absorbs less moisture than expected.

Over 15 years, EPS absorbs only 0.5% of the heat, making it the greatest attic and wall insulation. Furthermore, when moisture gets into small spaces, EPS can better evacuate it.

Considering that EPS has drying potential and XPS does not, there are even more reasons to choose EPS. Drying potential is particularly essential in thermal insulation since it aids in maintaining the optimal thermal resistance, also known as R-value, despite prolonged exposure to moisture and other dangers.



EPS (Expanded Polystyrene) has the advantage of being completely recyclable. EPS is readily recyclable at recycling facilities all across the country. There are around 200 EPS collection centers across the country, albeit few people are aware of them. EPS is recycled over 100 million pounds every year.

Cost per R-Value

The resistance of a material to heat transfer is measured by its R-value. The R-value of a material indicates how well it insulates. The ASTM C518 Standard Test Method is used to determine the R-value of rigid foam insulation. A technician must measure the product’s thermal resistance when placed between a cold and a hot plate in this testing technique.

While all rigid-foam insulation has high R-values, not all forms of rigid-foam insulation have the same level of thermal performance. Builders select EPS insulation for insulated concrete structures, structural insulated panels, and exterior insulation and finishing systems. With an R-value of only R-4 per inch, it has the lowest R-value. The R-value of foam insulations, on the other hand, varies depending on the density of each sheet of insulation. The higher the product’s density, the higher the R-value.


In the building industry, customization is increasingly becoming the norm. Customers and construction experts gravitate toward sheets that aren’t the standard 4′ x 8′. In terms of personalization, EPS is superior since it creates a wide range of shapes, sizes, and thicknesses. With a thickness of up to 48 inches, EPS can be utilized for crawl spaces, pre-cast concrete, wall furring, foundations, under a slab, sheathing, and various other applications. In contrast, XPS has a thickness of 3″ to 4″. In addition, EPS can reach R-209, but XPS is limited to R-15. Considering that EPS may be laminated, there are even more reasons to use this material.

Bonding Capability

The surface of EPS foam enables quick and deep bonding. XPS binding, on the other hand, is far more difficult. If you ask anyone in the Structural Insulated Panels and Exterior Insulated Finish System industries about these two materials, they will tell you that EPS has superior bonding capabilities. In addition, the packaging sector relies on EPS because of its excellent component bonding capabilities.

The Impact on the Environment

In terms of the environment, Expanded Polystyrene is superior to Extruded Polystyrene since EPS has never been created with HCFCs that are harmful to the environment and is unlikely to be made with them in the future. Furthermore, individuals concerned about the environment prefer EPS because it does not contain any dyes. Considering that EPS may be made from recycled materials, there are even more reasons to choose EPS over XPS.

On the other hand, XPS frequently includes colors and branding components. XPS is inconsistent when it comes to the utilization of recycled materials. The XPS product and manufacturer determine the amount of recycled material utilized.


EPS can be made in various densities, with a compressive strength of up to 8,640 pounds/feet and a flexural strength of up to 10,800 pounds/feet. Although EPS is made up of 98% air and is extremely light, it is potent. Add in the fact that EPS insulation R-value is superior to XPS insulation R-value due to its laminated poly facer application to board for increased durability and impact resistance, and you have yet another incentive to pick EPS.

In real-world applications, EPS is a superb insulating product. This testing technique is comparable to XPS. EPS is an excellent insulation solution for most applications, including walls, roofs, and below-grade applications, because it provides a high R-value at a reasonable price.

Learn more about the numerous types of insulation the Styrene Insulation Industry (SII) offers and how they can be used in your next project by clicking here. Alternatively, you can contact one of our representatives by clicking here to discuss your project’s requirements.


Our team is happy to answer your questions. Fill out the form and we will be in touch as soon as possible.