By: Pat Austin, Sales Representative – Architectural Products
Rigid foam insulation products are manufactured using a variety of plastic resins and other compounds, but if you’re like me you tell them apart visually by their color. Extruded polystyrene (XPS) is usually blue or pink. Polyisocyanurate (ISO) is typically yellow, but sometimes has a foil or grey paper facer adhered to it. Expanded polystyrene (EPS) is almost always white.
While color is the easiest method of distinguishing these products, for below-grade applications, there is more to the story than meets the eye. How each product performs when exposed to bulk moisture is a critical indicator of its effectiveness. Short-term laboratory testing would lead you to believe that XPS has the lowest water absorption in the field. However, recent 15 year in-ground moisture resistance testing has contradicted these claims. Regardless of how much water a rigid foam insulation absorbs, the question we need to answer is this: How much R-value remains? That is the question that matters as we try to heat and cool our buildings.
As it turns out BASF Corporation, perhaps the world’s largest producer of styrene monomer (the raw material used in production of both XPS and EPS), answered this question back in the early 1990’s. They tested 2″ XPS and EPS to see how much water each could take on while maintaining set R-value levels (94, 92, 90 and 87 percent). The differences are dramatic. EPS can absorb over 14X the moisture volume of XPS, and maintain 94% of its R-value. Read the BASF E2 Document.
Foam-Control Plus+ architectural grade EPS insulation is available in several grades (150, 250, 400 and 600) and thicknesses up to 40″
That is performance in action. No matter how you color it.