Choosing the right foam for SIPs

Choosing the Right Rigid Foam for Structural Insulated Panels: A Technical Guide

When it comes to selecting rigid foams for Structural Insulated Panels (SIPs), it's important to understand the different foam types available. At Formance, we use two variations of Expanded Polystyrene (EPS) in our panels due to their superior balance of performance, recyclability, and consistency in lamination. However, there are other rigid foams that people often confuse with our system, such as Extruded Polystyrene (XPS), Polyurethane (PUR), and Polyisocyanurate (PIR). In this article, we’ll break down the differences and explain why we choose EPS for our SIPs.

Types of Rigid Foam Insulation

Expanded Polystyrene (EPS)

EPS is a closed-cell foam that is widely used in SIPs due to its excellent thermal performance, cost-effectiveness, and sustainability. At Formance, we use two variations:

  • Standard White EPS – The traditional EPS material that provides a stable and reliable insulation performance.

  • Graphite-Infused EPS – This advanced formulation incorporates graphite particles, which enhance thermal performance by approximately 18%. For instance, a 115mm panel increases from R2.8 (standard EPS) to R3.3 (graphite-infused EPS), offering better energy efficiency.

EPS has several advantages:

  • Recyclability: Any offcuts produced in our factory are fully recycled, reducing waste and promoting sustainability.

  • Consistent Lamination: Unlike some other foams, EPS is not a 'blind product,' meaning it allows for precise and even lamination during manufacturing, ensuring high structural integrity.

Extruded Polystyrene (XPS)

XPS is another polystyrene variant, but unlike EPS, it is manufactured through an extrusion process, creating a foam with a more uniform structure and slightly higher moisture resistance. However, XPS is not used in Formance SIPs due to:

  • Limited recyclability – XPS does not recycle as efficiently as EPS, making it a less sustainable choice.

  • Higher cost – While offering marginally better moisture resistance, XPS comes at a significantly higher price point without a substantial performance gain in SIP applications.

Polyurethane (PUR) and Polyisocyanurate (PIR)

Both PUR and PIR foams are closed-cell, high-performance insulation materials that are sometimes used in panelized building systems. However, Formance does not use these foams for several reasons:

  • Inconsistent Lamination: These foams must be blown into a mould or cavity during production, meaning the density and adhesion to the SIP skins can vary. This creates potential weak points and reduces reliability in lamination.

  • Recyclability Issues: Unlike EPS, these foams are difficult to recycle, leading to more environmental waste.

  • Higher Cost with Marginal Benefits: While PUR and PIR do offer higher R-values per inch, their added cost and production challenges do not justify their use in our SIPs.

Insurance Considerations: Is EPS a Safe Choice?

PIR is often viewed more favorably by insurance providers, leading to lower premiums in some cases. However, this preference is largely due to historical fire performance concerns with polystyrene products, rather than the reality of modern EPS insulation.

In truth, EPS is a safe and stable insulation material when used correctly. Here’s why:

  • Fire Performance: The EPS used in Formance SIPs contains fire retardants that significantly reduce flammability. In a well-designed SIP structure with proper finishing layers, the risk of ignition and fire spread is minimal.

  • Proven Track Record: EPS has been used successfully in thousands of buildings worldwide, demonstrating its reliability in real-world applications.

  • Stable and Predictable Performance: Unlike some foams that degrade over time or release toxic fumes when exposed to heat, EPS remains stable and does not produce hazardous emissions.

The assumption that PIR deserves lower insurance premiums than EPS is often based on outdated information. When encapsulated in a SIP panel and covered with the appropriate fire-rated materials, EPS performs comparably to other insulation types in terms of fire safety.

Why Formance Uses EPS for SIPs

EPS is the optimal choice for our SIPs because it offers:

  • Proven Performance: Provides stable and consistent insulation properties.

  • Recyclability: Allows us to fully recycle offcuts, reducing environmental impact.

  • Structural Reliability: Ensures even lamination without hidden weak points.

  • Cost-Effectiveness: Delivers excellent thermal performance at a competitive price.

  • Safe and Reliable: When installed correctly, EPS performs to high safety standards, making it a responsible and efficient insulation choice.

By choosing the right rigid foam, builders and designers can ensure their SIP structures are high-performing, sustainable, and cost-efficient. At Formance, our commitment to using EPS ensures our panels deliver superior insulation, durability, and environmental responsibility.

 

Posted 42 hours ago by Corban Faulkner