According to Inspectapedia, basic brick walls have an insulation value, or R-value, of 0.2 per square inch. By comparison, plywood has an R-value of 2.5. Many “brick” homes are actually wood-framed homes with brick sheathing, and have insulation values comparable to other wood-framed buildings. Conventional 8 inch concrete block walls have an R-value of 0.08 per square inch, or about 2.5 for the whole block. Insulated concrete blocks can increase their R-value to about 1.2 per square inch, and air-entrained blocks can have R-values as high as 3.9.