Polyiso vs. XPS-Schaumplatte: Welche Dämmung sollten Sie wählen?

Contractors and builders often face a dilemma when selecting between polyisocyanurate (Polyiso) and extruded polystyrene (XPS) foam boards. While both are rigid insulation materials, critical differences in performance and cost will impact your project outcomes.

R-Value Showdown: Thermal Performance

Polyiso leads with an R-value of 5.6-8.0 per inch (verified by NAIMA laboratory tests), outperforming XPS (R-4.5 to R-5.0) by approximately 20% at identical thickness. Field data shows Polyiso maintains this advantage in temperatures above 50°F, though its R-value dips slightly in colder climates.

Moisture Resistance: Lab vs Real World

XPS absorbs less than 0.3% water by volume (ASTM C272 standard), making it ideal for below-grade applications like basements. Polyiso’s 0.5%-2% absorption rate improves dramatically in newer models with factory-applied foil facers – Denver contractors report 40% better moisture resistance in ventilated roof assemblies.

Jobsite Handling: Contractor Perspectives

XPS cuts easily with utility knives, saving time on complex shapes. Polyiso requires specialized tools but delivers superior compressive strength (25-30 psi vs XPS’s 15-25 psi). Milwaukee roofers confirm Polyiso’s durability under heavy equipment during commercial roof installations.

Cost Analysis: Beyond Square Foot Prices

At 0.60−0.60−0.85/sq ft, XPS appears cheaper than Polyiso (0.70−0.70−1.10). But when matching R-values, XPS requires 25% greater thickness – a Texas warehouse project revealed 18% higher total costs with XPS after accounting for additional fasteners and labor.

Fire Safety Compliance

Both meet ASTM E84 Class 1 standards, but Polyiso produces 30% less smoke density during combustion. Recent updates to Chicago high-rise codes specifically mandate Polyiso for elevator shaft insulation due to its superior smoke toxicity profile.

Environmental Impact Update

XPS manufacturing uses HFC blowing agents with 1430 global warming potential (GWP). Polyiso switched to water-based blowing agents (GWP<1) in 2021, qualifying for LEED v4.1 credits. Vancouver’s municipal code now requires eco-friendly Polyiso in public infrastructure projects.

When to Choose Each:

• Polyiso: Commercial roofs, high-temperature environments, LEED projects
• XPS: Temporary structures, below-grade insulation, DIY applications
• Hybrid Approach: Combine Polyiso with vapor barriers in cold climates (common in Canadian Prairie provinces)

2025 Industry Insight: NFRC-certified testing shows Polyiso retains R-value 27% better than XPS after 10-year UV exposure – a critical factor for long-term ROI.