polyiso insulation cost
ASTM test methods for determining a materialâs R-value. In the case of rigid foam insulation, this can be problematic. XPS has a published R-value of R5.0 per inch and polyiso is listed at a range of R5.6 to R6.0 per inch.â These values are true. when tested at a mean temperature of 75Â°F. However, building science research continues to show that the R-value of each.