What R-values do SIPs have?
The R-value of a SIP varies depending on the thickness and type of foam core used. According to a study by Oak Ridge National Laboratory, the “whole-wall” R-value of a wall with a 3-1/2″ EPS core is 14 compared to 9.8 for a 2″x 4″ wood framed wall insulated with R-11 fiberglass insulation. When the performance of the whole wall system is considered, SIPs perform better than traditional systems because they are manufactured in a controlled environment characterized by uniform fabrication of components without gaps or air pockets. They are also designed for efficient field installation that reduces air infiltration, and there are few thermal breaks or penetrations in the panels that are typical of wood frame construction.
