Why choose PIR vs EPS Insulation in Sandwich Panels

You can construct production facilities, warehouses, and even residential buildings quickly and with high energy efficiency using various types of insulation. However, choosing the right insulation material for your specific project can be challenging. How do you determine which option is most suitable?

This article compares two popular insulation materials: PIR and EPS.

Both Polyisocyanurate (PIR) and Expanded Polystyrene (EPS) are rigid insulation materials commonly used as the core of sandwich panels. At first glance, they may appear similar, but they possess distinct characteristics that set them apart in performance and application.

Technology

Polyisocyanurate (PIR) is a fire-resistant insulation material derived from polyurethane. PIR sandwich panels are produced on continuous manufacturing lines, where a fireproof PIR foam is injected between two metal facings. This manufacturing process creates a seamless and homogeneous insulation core, which significantly enhances the panel’s structural integrity, fire resistance, and thermal insulation properties when compared to EPS-core panels.

Expanded Polystyrene (EPS), on the other hand, is produced by expanding polystyrene polymer beads with steam. These beads are then dried, stabilized, and molded into large EPS blocks. In the manufacturing of EPS sandwich panels, the EPS is cut into lamellas and bonded to the metal facings using adhesive. This method results in lower bonding strength and diminished thermal performance compared to PIR panels, which can negatively impact the overall insulation and durability of the finished product.

Thermal Conductivity

One of the most critical factors to consider when selecting insulation is its energy efficiency, which is measured by thermal conductivity. Polyisocyanurate (PIR) panels offer outstanding performance in this regard, with a thermal conductivity as low as 0.022 W/m·K—one of the lowest among all insulation materials available globally. In contrast, Expanded Polystyrene (EPS) panels have a higher thermal conductivity of approximately 0.037 W/m·K.

The rule is simple: the lower the thermal conductivity, the better the material insulates. Under the same environmental conditions, a building constructed using PIR-core sandwich panels will retain heat or cold approximately 68% more effectively than one built with EPS panels. This superior insulation performance translates into significant energy savings for heating and cooling over time, making PIR sandwich panels a more efficient and cost-effective choice for long-term building performance.

Panel Thickness

Thanks to its lower thermal conductivity, PIR insulation achieves the same thermal performance with significantly less thickness. For example, a 100 mm thick PIR Premier sandwich panel can insulate just as effectively as a 160 mm thick EPS panel. This reduction of 60 mm in panel thickness not only saves material space but also increases the usable interior area of the building. Choosing PIR sandwich panels allows for more efficient space utilization without compromising thermal performance.

Reaction to Fire

Fire safety is a crucial consideration when choosing insulation materials. For wall and roof sandwich panels with a thickness of 100 millimeters, PIR sandwich panels offer superior fire resistance, with ratings of EI30 and RE30. This means the panel can maintain its integrity and load-bearing capacity for up to 30 minutes during a fire. In comparison, EPS panels offer significantly lower fire resistance, with ratings of only EI15 and RE15, regardless of insulation thickness. In the event of a fire, EPS panels will begin to lose their structural properties after just 15 minutes, whereas PIR panels provide a longer window of stability and protection.

Moisture Resistance

When it comes to moisture resistance, both PIR and EPS perform similarly. They are composed of closed-cell structures, which means they do not absorb water. This closed-cell design prevents moisture penetration, helping to preserve the insulation's effectiveness over time and reducing the risk of mold or water-related degradation.

Resistance to Rodents

PIR sandwich panels have a solid, rigid structure made from densely packed closed cells. This makes them unappealing and impenetrable to rodents such as rats and mice. On the other hand, EPS is made from expanded polystyrene beads fused together with steam, resulting in a softer, less dense structure. This texture can attract rodents, who may chew through the material, potentially compromising the insulation and overall structural integrity of the panel system.

Key Differences Between EPS and PIR Insulation Panels

Installation Differences: Practical On-Site Considerations

From a construction standpoint, both EPS and PIR insulation boards are relatively straightforward to install. However, several practical differences may influence the choice of material.

Cutting and Handling

PIR panels have a firmer, more dimensionally stable structure, allowing for clean, precise cuts with basic tools. EPS panels are also easy to cut but tend to crumble, which can affect edge quality and may require additional sealing during installation.

Panel Thickness and Jointing

Because PIR delivers a higher R-value at a thinner thickness, it can meet insulation requirements with slimmer panels. This often results in fewer joints, faster installation, and improved airtightness in certain building systems.

On-Site Fire Safety

PIR panels generally perform better under heat or flame exposure, making them a safer choice during installation—particularly in areas where hot tools, welding, or other heat-generating activities are present.

Despite these differences, EPS remains a practical option for budget-sensitive projects or applications with less stringent fire and insulation requirements. With proper installation and moisture management, EPS can still provide reliable thermal performance across many building types.

Conclusion: Choosing the Right Panel for Your Project

Selecting between EPS and PIR insulation boards ultimately depends on your project’s performance goals, budget, and regulatory requirements.

If cost is the main priority and the application does not require high fire resistance or exceptionally low thermal conductivity, EPS panels provide an economical and practical solution.

If your project focuses on energy efficiency, long-term durability, and enhanced fire performance, PIR panels offer superior results and are worth the higher upfront investment.