There is a table of building material R-Values further down in this article, but first we should quickly cover some basics about R-Values, U-Factors, and calculating thermal resistance.

In construction, the R-value is the measurement of a material's capacity to resist heat flow from one side to the other. In simple terms, R-values measure the effectiveness of insulation and a higher number represents more effective insulation.

R-values are additive. For instance if you have a material with an R-value of 12 attached to another material with an R-value of 3, then both materials combined have an R-value of 15.