Skip to main content
The International Institute of Building Enclosure Consultants (IIBEC) Interface
Moisture Absorption in Polystyrene Insulation: Effects on In-Serive Design R-Values
Moisture absorption is a familiar concept. It is easy to understand moisture absorption mechanisms in polystyrene insulation. Unfortunately, some insulation-performance claims can be misleading when based on test results from a few field samples or extrapolations of long-term field performance from small-scale laboratory tests of limited duration and exposure.
Ideally, engineers and specifiers would have access to peer-reviewed data from known scientific institutions to sort through the marketing claims. Sophisticated mathematical modeling is emerging to help predict polystyrene insulation performance in a range of climate conditions, but in the meantime, long-term field research studies are the best resource for reliable information.
This article originally appeared in the November 2020 issue of IIBEC Interface. IIBEC Interface is the technical journal of the International Institute of Building Enclosure Consultants (IIBEC). The institute intends that IIBEC Interface educate and inform, establish common ground for discussion, and provide a forum for the exchange of ideas and technical knowledge. Visit IIBEC online at to learn more.