Better for Roof Insulation: Phenolic Insulation Board or XPS Board
As energy efficiency becomes a global construction priority, the selection of the right roof insulation material is more important than ever. Two popular options on the market today are phenolic insulation board and extruded polystyrene (XPS) board. While both materials offer thermal performance, they differ significantly in key areas that can impact building safety, energy use, and long-term durability. Thermal Efficiency One of the main reasons to insulate a roof is to reduce heat loss and control indoor temperatures. In this regard, phenolic insulation board stands out. With an exceptionally low thermal conductivity (typically 0.020–0.023 W/m·K), phenolic foam provides excellent insulation using less thickness. XPS also offers good thermal performance, but its conductivity is higher — around 0.030–0.035 W/m·K — meaning thicker layers are required to achieve the same U-value. Fire Performance This is where phenolic insulation clearly ha...