What is the R-value of EPS?
The R-Value of the 1.5 pound density foam we use is an R-4.5 per inch. As the density of the EPS increases above about 2 lb/ft3, the convection of heat increases while the R-value decreases. Thus, the most effective use of expanded polystyrene as an insulator is generally within the range of about 0.9 to 2.0 pcf.