Homeowners, architects, builders and home improvement contractors continue to ask questions about the various insulating materials available in the building and remodeling industry today. Some of the questions that we hear regularly regard open-cell vs. closed- cell insulation: “Which one absorbs water? Which one works better? Which one insulates better? Which one is siding insulation made from?”
To answer these questions, we will look at the main differences between open-cell and closed cell foams.
What is Open-Cell Foam?
Open-cell foams are typically soft, like the foam in a sofa cushion. The cell walls are broken, allowing air to fill all of the spaces in the material. This makes the foam soft, perfect for packaging to protect a new digital camera, or for sound-proofing.
Because of this softness, open-cell foams are not typically used in construction or building materials. Additionally, open-cell foams do not perform well when exposed to water since the openness of their structures allows water to be absorbed into the foam (think of your sofa cushions being soaked in water).
What is Closed-Cell Foam?
In contrast, closed-cell foams, including Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS), differ in that all of their tiny foam cells are closed and packed together. As building products, the advantages of closed-cell foam are many. Due to their structures, closed-cell foams have a higher compressive strength for greater impact resistance. They can withstand impact from hail and other weather extremes. Exposure to water does not affect them since the closed cells allow only minimal amounts of moisture to be temporarily absorbed into the microscopic spaces between the cells. Neither their R-values nor structural integrity is compromised by any of this minimal and temporary absorption. Because the closed-cell foams contain an insulator (air) within their cells, the R-value of closed-cell foams exceeds that of open-cell by a wide margin.
Is Progressive Foam Closed-Cell?
Yes. At Progressive Foam, all of our siding insulation products are closed-cell foams. EPS maintains its shape and structural integrity due to its high compressive strength. Even after repeated water submersion tests (ASTM C272), only nominal amounts of moisture (less than 3%) was absorbed into EPS foam. In recent field performance tests on insulated vinyl siding taken from homes in the state of Minnesota, the average moisture content was only 1.4% (report available upon request). Additionally, because the structure of EPS closed-cell foam maintains its integrity throughout its lifetime, users are assured they are receiving the promised r-value for the life of the siding insulation.