R-value refers to resistance to heat flow, and is the metric by which insulating power is measured. The higher the R-value, the greater the insulation performance, energy efficiency, and climate control within the dwelling. The R-value of insulation is dependent upon the insulation type, thickness, and density of insulation material. Foam board insulation has the ighest average R-value per inch. R-value can be a useful tool in determining which insulation type is optimal for your application.
Regional R-Values
The US Department of Energy generated the map below as guidance on the minimum recommended R-value in insulation application in each region.
R-Value Insulation Chart
Multiple layers of insulation can be used to achieve the desired R-values depicted in the chart above.