The R Factor: Vinyl Vs. Brick

Vinyl

• The standard R-value given to vinyl siding is 0.61. The R-value measures the thermal resistance of the siding, and the higher the R-value, the better it performs to insulate the interior of the home from either heat or cold. However, that is just the R-value for the vinyl. Other materials are involved. A typical vinyl-clad home might have a sheet of film, plywood sheathing and drywall, an air film inside the wall cavity and fiberglass insulation. These materials have a combined R-value total of 13.73, according to Colorado Energy.org. So when you add the value of the vinyl, the grand total R-value is 14.34 (13.73 plus 0.61).

Brick

• A 4-inch block of brick has an R-value of 0.44. This means that the R-value for brick is about 28 percent less than the R-value for vinyl. Now let's add the total R-value, using the same materials as in the example for the vinyl-clad home. The R-value for the outside air film is 0.17, the R-value for the wood bevel siding is 0.80, the plywood sheathing is 0.63, the ½-inch drywall R-value is 0.45, the inside air film has an R-value of 0.68, and the fiberglass insulation has an R-value of 11.00, which, again, gets us to the 13.73 total. When you add the brick, the R-value climbs to 14.17 for all the wall components.

Comparison of Brick and Vinyl

• The total R-value for the vinyl example is 14.34, and the total for brick is 14.17 -- representing a 0.17 difference, which equates to a 1.2 percent difference. So, when you look at the grand total R-value for the wall assembly, the difference between brick and vinyl seems less significant. This is a more realistic way to compare the R-factors and mirrors what takes place in life. Factor the additional materials used to build and insulate a home to compare the two materials fairly and objectively.

Considerations

• As you can see, insulation plays the biggest role in determining the total R-value. The 3½-inch blanket of fiberglass insulation has an 11 R-value. However, the "R-factor" will be different if you use a different type or different density of insulation. The R-value of rigid fiberglass is 4.0, and other fiberglass varieties have R-values as high as 4.3. If you selected prefabricated insulated vinyl, the R-value can increase by as much as 25 percent, giving the vinyl a base R-value that jumps from 0.61 to around 0.85 or higher. The "R-factor" for vinyl and brick can increase significantly once you factor every component used to assemble a home from the outside to the area inside the wall cavity.