What insulation systems are available and what are the differences?

There are 2 types if insulation systems:

  1. Expanded Polystyrene (EPS) Insulation
  2. Extruded Polystyrene (XPS) Insulation

EPS insulation consists of granules of polystyrene infused with pentane. The granules or beads are poured into a mold and are injected with steam. The steam softens the beads and increases the gas pressure of the pentane trapped inside the mold. The pressure causes the pentane gas to expand, which in turn causes the beads to expand and melt together, taking shape of the mold. The typical uses of EPS insulation are in disposable coolers and packaging materials.

The problem with EPS insulation is that the process creates voids or air pockets, like tennis balls in a bucket. Unfortunately, these voids and air pockets have several disadvantages:

  • They are permeable to water.
  • They have less compressive strength and lower density.
  • They are less resistance to water vapor.
  • They have a lower R-value per inch.

In contrast, XPS insulation is made by taking the same polystyrene plastic granules and feeding the material into an extruder, which melts the granules into a thick liquid. Heat and pressure are exerted, along with the addition of a liquified blowing agent. The substance is then extruded through a die to form a board. The added blowing agent forms bubbles in the liquid polystyrene. The extruded material cools quickly and becomes a solid board. This process produces unique closed cells where no voids or air pockets appear. This closed-cell structure gives XPS the following positive characteristics:

  • It has the highest long-term insulation value.
  • It is impermeable to water.
  • It has higher compressive strength.

· It has a higher R-value per inch.

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