R Value Of Concrete Wall Below Grade

The r value of an uninsulated 8 inch thick basement wall built using normal weight concrete is 1 35 based on data from the 1993 american society of heating refrigeration and air conditioning engineers handbook.

R value of concrete wall below grade.

The r value listed by pca for a normal weight 144 pcf 6 inch concrete wall is 1 23 and includes inside and outside air film resistances which contribute to overall thermal resistance. R 0 125 per inch for soil sounds pretty reasonable if we assume about 20 moisture content and if we consider for comparison or a sanity check that the r value of uninsulated concrete is about r 0 8 inch. Find your zone on the map and then use the above insulation r value chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. The higher the r value the better the thermal performance of the insulation.

Ensure minimal long term moisture absorption. In addition the doe recommends r 10 to r 20 insulation for under a slab which we have not taken into consideration for this article. In addition to r value stability rigid foam insulations differ in their rates of moisture absorption and their ability to dry. R value is a measure of insulation s ability to resist heat traveling through it.

564 to obtain copies of this reference. Concrete block wall with perlite in cavities r 2 9. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. By doubling the thickness of the wall to 16 inches the r value only increases by 0 50.

The table below shows what levels of insulation are cost effective for different climates and locations in the home. The minimum insulation r value recommended by the department of energy for horizontal below grade surfaces in cold climates is r 10 to r 15. Above grade concrete wall including inside and outside air films r 1 2 for 6 inch r1 4 for 8 inch. Other engineering sources cite the r value of earth as about r 0 25 per inch or double our calculation.

By comparison most xps warranties typically cover only up to 90 percent of the published r value to account for the r value degradation that occurs in the field. Concrete block wall with air in cavities r 2 0. For example if you have a type of insulation.