Expanded polystyrene (EPS) is a rigid closed cell/cellular plastic resin made from petrochemicals derived from crude oil. The resin is incorporated with the blowing agent pentane. During the pre-expansion, steam softens the plastic resin causing the pentane to expand the plastic into beads at least 100 times their original size.


As long as the plastic is exposed to steam, the longer the pentane expands, therefore determining the expanded size of the bead. Before all of the pentane is displaced by air, the pre-expanded bead is then placed into a mold of any shape or block.





Blocks are then cut to desired size with hot wires, wrapped, and shipped.

Other EPS Facts:
– EPS does NOT contain CFC’s, HCFC’s, or formaldhyde.
– EPS does NOT contribute to the growth of mold or mildew.
– EPS is considered to be no more toxic than Douglas Fir wood under the worst case fire scenario.
– EPS is manufactured in accordance with ASTM C578.
– EPS is recyclable.    





Benchmark Foam’s EPS products are used in building envelope applications essential to achieving energy savings in new construction and building renovations. To learn how our products may qualify for federal tax credits and obtain our Manufacturer’s Certification Statement, click here.


Benchmark Foam, Inc., 401 Pheasant Ridge Drive, Watertown, South Dakota 57201  

Phone 605-886-8084     Toll-free 800-658-3444     Fax 605-886-8099

Products Made In The USA!

EPS is a lightweight, versatile, economical, recyclable material that can be tailored to meet changing and complex requirements. Select one of the following topics to learn more: