R Value measures the thermal resistance of heat transfer through the product. The higher the R Value, the less heat is transferred through the product and therefore exhibits greater insulation properties. This value is measured as a reciprocal of the rate of heat transfer in watts, through one square meter of structure, divided by the difference in temperature across the structure. It is expressed in watts per square meter Kelvin. A roofing system with Scrim Facing Insulation has an R Value of between 1.45 and 1.6, tested using standard ISO6946.
