R Value Of Concrete Wall Below Grade

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.

R value of concrete wall below grade.

Depending on the density of the blocks an 8 inch thick block wall without any other type of. 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. And sheath it with 1 3cm sheets of thermax and 1 3cm sheetrock the total r value would be 14 75. 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.

The reason that it is important to make a good estimate for the current r value for uninsulated spaces is that small changes in r values result in large changes in heat loss when the total r value is low. 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. By doubling the thickness of the wall to 16 inches the r value only increases by 0 50. If you are building your house you have the advantage of being able to insulate properly right from the.

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 perlite in cavities r 2 9. Other engineering sources cite the r value of earth as about r 0 25 per inch or double our calculation. Ensure minimal long term moisture absorption.

Concrete block makes a cost effective and structurally sound wall but it has little thermal resistance. 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.