Expanded Polystyrene vs. Extruded Polystyrene

What's the Difference?

Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS) are two common types of polystyrene foam insulation materials. EPS is made by expanding polystyrene beads with steam, resulting in a lightweight and highly insulating material. It is commonly used in packaging, construction, and insulation applications. On the other hand, XPS is manufactured by extruding molten polystyrene through a die, creating a dense and rigid foam board. XPS offers better moisture resistance and higher compressive strength compared to EPS, making it suitable for applications where moisture control is crucial, such as below-grade insulation or roofing. Both EPS and XPS provide excellent thermal insulation properties, but their manufacturing processes and physical characteristics make them suitable for different applications.


AttributeExpanded PolystyreneExtruded Polystyrene
CompositionExpanded polystyrene beads fused togetherPolystyrene mixed with blowing agents and extruded
DensityLow densityHigher density
Insulation PropertiesGood insulation propertiesExcellent insulation properties
StrengthLower strengthHigher strength
Moisture ResistanceLow moisture resistanceHigh moisture resistance
CostRelatively lower costRelatively higher cost
ApplicationsInsulation, packaging, disposable productsInsulation, construction, marine applications

Further Detail


Polystyrene is a versatile and widely used plastic material that is commonly found in various applications, ranging from packaging materials to insulation products. Two popular forms of polystyrene are expanded polystyrene (EPS) and extruded polystyrene (XPS). While they share some similarities, they also have distinct attributes that make them suitable for different purposes. In this article, we will explore and compare the attributes of EPS and XPS, shedding light on their unique characteristics and applications.

1. Manufacturing Process

EPS and XPS are both derived from polystyrene, but they are manufactured using different processes. Expanded polystyrene is created by expanding polystyrene beads with the help of steam, which causes the beads to fuse together and form a rigid foam material. On the other hand, extruded polystyrene is produced by melting polystyrene resin and then extruding it through a die, resulting in a continuous, closed-cell foam board.

Due to their distinct manufacturing processes, EPS and XPS exhibit variations in their physical properties and performance characteristics.

2. Density and Strength

One of the primary differences between EPS and XPS lies in their density and strength. Expanded polystyrene typically has a lower density compared to extruded polystyrene. This lower density makes EPS lightweight and easy to handle, making it a popular choice for packaging materials and disposable food containers.

On the other hand, extruded polystyrene has a higher density, which contributes to its increased strength and durability. XPS is known for its excellent compressive strength, making it suitable for applications that require load-bearing capabilities, such as insulation for foundations and roofing.

While EPS may be less dense and have lower strength compared to XPS, it still offers sufficient insulation properties for many applications, such as wall insulation and protective packaging.

3. Thermal Insulation

Both EPS and XPS are widely used as insulation materials due to their excellent thermal insulation properties. However, they differ in terms of their insulation performance and moisture resistance.

Expanded polystyrene has a lower thermal conductivity compared to extruded polystyrene, which means it provides better insulation against heat transfer. EPS is commonly used in applications where high thermal resistance is required, such as insulating concrete forms (ICFs) and insulated panels for walls and roofs.

Extruded polystyrene, on the other hand, offers superior moisture resistance due to its closed-cell structure. XPS is less permeable to water vapor, making it suitable for applications where moisture control is crucial, such as below-grade insulation and insulating basement walls.

Both EPS and XPS have their strengths in terms of thermal insulation, and the choice between the two depends on the specific requirements of the application.

4. Environmental Considerations

When it comes to environmental considerations, both EPS and XPS have their pros and cons.

Expanded polystyrene is often criticized for its potential impact on the environment due to its non-biodegradable nature. However, EPS can be recycled, and many recycling facilities accept EPS materials. Additionally, EPS has a lower carbon footprint compared to other insulation materials, making it a relatively eco-friendly choice.

Extruded polystyrene, on the other hand, is not easily recyclable due to its manufacturing process and the presence of flame retardants. However, XPS can be reused in certain applications, such as insulation boards for construction projects. It is worth noting that both EPS and XPS can contribute to landfill waste if not properly managed.

Ultimately, the environmental impact of EPS and XPS depends on factors such as recycling infrastructure, waste management practices, and the specific application of the materials.

5. Cost

Cost is an important consideration when choosing between EPS and XPS, as it can significantly impact the overall project budget.

Expanded polystyrene is generally more cost-effective compared to extruded polystyrene. The manufacturing process of EPS is simpler and less expensive, resulting in a lower price point for EPS products. This affordability makes EPS a popular choice for various applications, including packaging, insulation, and disposable products.

Extruded polystyrene, on the other hand, tends to be more expensive due to its higher manufacturing costs. The additional steps involved in the extrusion process, as well as the higher density and strength of XPS, contribute to its higher price tag. However, the enhanced performance and durability of XPS may justify the higher cost in certain applications that require superior insulation and load-bearing capabilities.


Expanded polystyrene (EPS) and extruded polystyrene (XPS) are two popular forms of polystyrene with distinct attributes and applications. EPS is lightweight, cost-effective, and offers excellent thermal insulation properties, making it suitable for packaging materials, disposable products, and various insulation applications. On the other hand, XPS provides enhanced strength, moisture resistance, and load-bearing capabilities, making it ideal for applications that require durability and superior insulation performance.

When choosing between EPS and XPS, it is essential to consider factors such as density, strength, thermal insulation, environmental impact, and cost. By understanding the unique characteristics of EPS and XPS, individuals and businesses can make informed decisions and select the most suitable polystyrene material for their specific needs.

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