Polyiso vs EPS vs XPS: Which Foam Board Is Best for Energy Efficiency?
By Graham Mann | Published: 11/9/2025
Explore the differences between Polyiso, EPS, and XPS foam boards to find the best insulation for energy efficiency based on climate and budget.
Polyiso vs EPS vs XPS: Which Foam Board Is Best for Energy Efficiency? When choosing between Polyiso(https://diyecohomes.com/blog/polyiso-insulation-pros-cons-when-to-use/), EPS, and XPS foam boards for insulation, your decision depends on climate, application, and budget. Here's a quick breakdown: - Polyiso: Offers the highest initial R-value (R-6.0 to R-6.8 per inch) but loses efficiency in cold temperatures. Best for roofs and walls in warmer climates or stable indoor conditions. - EPS: Affordable with consistent R-value (R-3.6 to R-4.2 per inch) across temperatures. Ideal for budget-friendly projects, interior walls, and below-grade insulation. - XPS: Excels in moisture resistance and compressive strength with a reliable R-value (R-5.0 to R-5.2 per inch). Perfect for basements, foundations, and wet environments, though it’s the most expensive option. Quick Comparison | Feature | Polyiso | EPS | XPS | |---| --- |---| --- | | Initial R-Value | R-6.0 to R-6.8 | R-3.6 to R-4.2 | R-5.0 ...
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