Performance of molded expanded polystyrene (EPS) thermal insulation in below-grade applications

Molded expanded polystyrene (EPS) products are used for a wide variety of construction applications, including such applications as thermal insulation for below-grade foundations, frost-protected shallow foundations and floor slabs. The performance of EPS thermal insulation has been demonstrated in these applications for more than 40 years. When used as below-grade insulation in building construction, EPS insulation is one component in a system whose purpose is to minimize heat loss and, in turn, energy consumption in that portion of the building envelope. As with any product, the successful use of EPS insulation depends upon its correct installation in accordance with good building practice. Material properties required for the selection of the correct EPS insulation product for below-grade applications and performance characteristics are discussed in this paper In addition to identifying material properties considered important in below-grade applications, current laboratory test methods used for measuring the property, where applicable, and references demonstrating performance of EPS product after defined in service periods are cited. The role each material property plays in the performance of EPS insulation is also highlighted.