DuPont™ Styrofoam™ Brand Square Edge ST-100 Extruded DuPont™ Styrofoam™ Brand Square Edge ST-100 Extruded Polystyrene (XPS) Foam Insulation* is a grey, extruded polystyrene foam (XPS) insulation board that provides continuous insulation over steel stud or wood framing, in masonry unit cavity walls, conventional roofs and meets the needs of the commercial foundation and building floor slab needs. It can also be used for attics, foundations/slabs and crawl spaces in residential applications.

With more than 60 years of proven performance in wet  environments, the closed-cell structure of Styrofoam™ Brand Square Edge ST-100 Insulation resists water pickup, enabling it to retain a high R value** over time – a necessary property in wet, below-grade commercial foundation and commercial roofing applications.

Styrofoam™ Brand Square Edge ST-100 Insulation is classified as a Type IV product when tested in accordance with ASTM C578 and provides a long term insulating performance of R-5 per inch.