Understanding the difference between the types of rigid foam insulation can save you considerable material cost and improve energy performance for the life of the project.  An evaluation of EPS insulation and XPS insulation is essential to cost savings and selecting the right product for the right use.

First both EPS and XPS are made from Polystyrene resin material.  However, the manufacturing process is completely different for the different products.  EPS manufacturing, the plastic resin is expanded through heat and pressure and molded to form a closed-cell material that uses trapped air as its insulating medium.  For XPS plastic resin is liquefied and then extruded through a die to form a closed cell material that also uses trapped air as its insulating medium.

Compressive Strength:  The compressive strength is similar for both products however the XPS can be commonly available in a slightly higher density than EPS.
Recycled Content:  EPS can typically contain 10-15% recycled content where recycled content is limited or not available in XPS material.
Environmental Quality and Sustainability:  As it relates to the environment and sustainability EPS has never contained any HFCs CFCs or HCFC, formaldehyde or color dies.   XPS on the other hand generally contains HFCs such as HFC134a.  HFCs are harmful to the environment.  XPS contains color dies giving it a pink, blue or green color brand to differentiate the product manufacturers.
Material Sizes:  EPS is available in widths from 8”-48” and lengths from 2’-16’ and in a wide variety of thicknesses of ½” up to 36”.  XPS is offered in widths of 16”, 24” or 36” with lengths limited to 8’ and thicknesses of ¾”, 1”, 1-1/2”, 2” or 3”.  Basically, EPS is “block material and XPS is sheet material.
Material Cost:  Finally, if the cost of the material will have a significant impact on your decision, you can count on the same compressive strength or R-Value EPS will cost 10% to 40% less per unit measure than the XPS.

Tags: eps geofoam, xps geofoam