When it comes to choosing insulation, the debate between EPS (Expanded Polystyrene) and XPS (Extruded Polystyrene) is a big one. Both are made from polystyrene, but their differences in performance, cost and environmental impact can make or break a project.
At Benchmark Foam, we know that the right insulation isn’t just about keeping heat in, it’s about long-term value, durability and sustainability.
So, which one wins in the battle of EPS vs. XPS? Let’s break it down.
R-Value Stability: Does It Hold Up Over Time?
R-value measures how well insulation resists heat flow. While both EPS and XPS start strong, their performance changes over time.
- EPS typically offers R-4 per inch at 75°F, increasing slightly at lower temperatures due to its air-filled structure. Since EPS relies on trapped air (not blowing agents), its R-value remains stable for years
- XPS may start with a higher initial R-value, but it uses blowing agents that slowly escape, causing a gradual decline in thermal resistance.
Over time, EPS often outperforms XPS in real-world conditions.
Water Resistance: Lab Tests vs. Real-World Performance
Moisture can impact the performance of insulation, so water resistance matters, but lab results don’t always tell the full story.
- XPS has a closed-cell structure, making it look better in short-term lab tests (absorbing only 0.3% moisture when submerged).
- EPS absorbs slightly more in lab settings (around 2%), but here’s the twist: field studies show EPS dries faster and holds less water long-term. After 15 years underground, XPS retained up to 19% moisture, while EPS stayed at just 5%.
Why? EPS beads don’t trap water like XPS’s dense structure. Moisture moves around the beads and drains away, preventing long-term damage.
In real-world conditions, EPS handles moisture better than XPS.
Customization:
Not all projects are the same, and sometimes you need insulation that can adapt.
- EPS is the shape-shifter of insulation. It can be molded into curves, notches and complex designs, making it ideal for unique architectural features or custom builds. It’s also easier to order in small batches for prototyping.
- XPS comes in rigid panels, limiting its use to flat surfaces. If your project needs intricate cuts or special contours, XPS falls short.
Environmental Impact:
Sustainability is a necessity.
- EPS is more eco-friendly in production and disposal. It uses pentane (a low-impact blowing agent) and can be fully recycled into new EPS products. Many facilities accept EPS waste, reducing landfill use.
- XPS relies on HFCs (harmful greenhouse gases) during manufacturing, contributing to ozone depletion. It’s also harder to recycle due to dyes and coatings, meaning most ends up in landfills.
Cost: Getting the Most for Your Budget
Money matters, and EPS delivers big savings.
- EPS costs about 30% less than XPS for the same R-value.
- XPS is pricier due to its manufacturing process and heavier weight, which also increases shipping and handling costs.
The Verdict: EPS or XPS?
Both materials have their place, but for most projects, EPS is the smarter pick. It offers:
- Stable R-value
- Better real-world moisture performance
- Superior customization for unique designs
- Lower environmental impact
- Significant cost savings
XPS has its strengths (like higher initial compressive strength), but unless your project demands those specific traits, EPS is the all-around winner.
At Benchmark Foam, we stand by EPS for its reliability, versatility and sustainability. Ready to make the right choice for your next project? Let’s talk insulation.
