The Insulation Battle: Comparing XPS, EPS, and Polyiso Insulation
The choice of insulation materials impacts a building’s thermal performance, longevity, and environmental footprint. Three main types of rigid board insulation dominate the market:
Expanded Polystyrene (EPS)
Extruded Polystyrene (XPS)
Polyisocyanurate (Polyiso)
While each material offers unique properties, EPS increasingly stands out for its sustainability, cost-effectiveness, and stable performance.
Expanded Polystyrene (EPS)
EPS is a versatile, eco-friendly insulation solution with stable long term thermal resistance. It is recyclable, manufactured without harmful blowing agents, and provides R-Values around 4 F.ft2.hr/Btu per inch, with increased thicknesses enhancing thermal performance. Its flexibility, affordability, and environmentally safe production make it a competitive option for numerous applications.
Expanded Polystyrene (EPS) insulation
Extruded Polystyrene (XPS)
XPS is a closed-cell foam insulation known for its rigid structure and moisture resistance, often used in below-grade and wall applications. It offers moderate R-Values, typically around 5 F.ft2.hr/Btu per inch. However, the use of hydrocardons (HFCs) as blowing agents in its production contributes significantly to its global warming potential (GWP), lowering its sustainability profile.
Extruded Polystyrene (XPS) insulation
Polyisocyanurate (Polyiso)
Polyiso, another closed-cell foam insulation, is known for its high initial R-Values (6.5+ F.ft2.hr/Btu per inch) and is commonly applied in roofing and wall applications. However, according to recent studies, Polyiso’s R-Value diminishes with time and low temperature. Polyiso is formulated using an isocyanate and polyol mixture while the facers include glass fiber reinforced felt, coated fiberglass mat, and aluminum foil to enhance durability.
Polyisocyanurate (Polyiso) insulation
Key Differences and Considerations
On paper it might seem smart to choose insulation based on initial R-Value alone, however factors such as environmental impact, long-term thermal stability, and moisture resistance offer distinct advantages and potential drawbacks for each insulation type.
Environmental and Health Impacts
EPS insulation stands out environmentally due to its absence of HFCs, hydrochlorofluorocarbons (HCFCs), chlorofluorocarbons (CFCs), or formaldehyde. With its recyclable nature, EPS minimizes landfill contributions at the end of its lifecycle. Unlike XPS and Polyiso, EPS is manufactured without blowing agents, making it a lower-impact choice.
Did you know that the EPS manufacturing process uses water and steam? Polystyrene beads are expanded and fused after being exposed to steam, creating a closed-cell structure that contains air, making it ideal for a variety of applications including construction, packaging, shipping, and food storage.Long-Term Thermal Resistance (LTTR)
XPS and Polyiso offer high initial R-Values but suffer from R-Value loss over time due to the diffusion of gases, which are gradually replaced by air in the foam cells. EPS, however, maintains stable thermal resistance across varying conditions, making it an attractive choice for consistent, long-term performance.
Studies conducted by Building Science Corporation reveal that Polyiso’s effectiveness decreases further at low temperatures, particularly below freezing. This temperature-dependent performance limits its reliability in colder regions. This temperature dependency and gradual performance loss reduce Polyiso’s effectiveness, especially in colder climates.
Moisture Absorption and R-Value Loss
Researchers found that EPS insulation installed below grade absorbs less moisture than XPS and retains more of its R-Value. The EPS Industry Alliance conducted an extensive 15-year in-situ study comparing EPS and XPS R-Values in below-grade installations placed side by side. The results revealed that EPS outperformed XPS, showing significantly lower water retention, as illustrated in the graph below. This high water uptake correlated directly with a notable decline in thermal performance for XPS, where R-Value loss was proportional to the moisture absorbed.
Installation Ease and Cost Efficiency
The lightweight nature of EPS allows for quick installation, which can shorten project timelines and reduce labor costs. Generally, EPS costs less than XPS or Polyiso, making it a cost-effective choice without sacrificing performance or durability.
Why EPS is the Best Choice
EPS insulation is the optimal choice for sustainable, effective, and cost-conscious building insulation. Here’s why EPS excels:
Recyclability: Fully recyclable, EPS supports a sustainable lifecycle.
No Harmful Chemicals: EPS is produced without HFCs, HCFCs, CFCs, or formaldehyde, minimizing environmental impact.
Stable Long-Term Thermal Resistance: EPS maintains consistent R-Values over time and across temperature variations.
Moisture and Mold Resistance: Has vapor barrier potential. Does not promote the growth of mold and mildew.
Affordability and Lightweight: EPS is cost-effective, easy to handle, and quick to install, reducing project timelines and costs.
Versatile Applications: With its stability and performance, EPS serves below-grade, roof, wall, and other insulating applications well.
Why Alleguard?
Alleguard stands as a leading provider of EPS insulation solutions, distinguished by its commitment to quality, sustainability, and industry innovation. Here’s how Alleguard makes the difference:
Expertise in EPS Construction Solutions
With decades of experience, Alleguard supports architects, contractors, and builders with advanced EPS products and expert guidance. Alleguard’s technical knowledge and industry insights ensure that its EPS insulation solutions meet the specific needs of each application, from below-grade installations to roofing and walls.
Innovative Product Options for Diverse Applications
Alleguard’s product range includes unique EPS solutions, such as Amvic™ Insulated Concrete Forms, Amdrain for drainage applications, and Ampex Radiant Floor Heating panels. This versatility allows Alleguard to provide custom solutions that enhance thermal efficiency, reduce project timelines, and contribute to resilient building designs.
Commitment to Quality and Safety Standards
Alleguard’s EPS products meet rigorous industry standards for safety, durability, and performance. Each product undergoes extensive testing to ensure it can withstand various environmental factors, providing reliable insulation and enhancing the longevity of construction projects.
For projects seeking sustainable, high-performing, and innovative EPS insulation solutions, Alleguard provides unmatched quality and expertise, empowering builders to achieve energy-efficient, cost-effective, and environmentally conscious results.