Dry coarse-grained sand may be used as a substitute for the insulation required by code in a buried pipe situation. The sand should have a maximum particle size of ¼” and a moisture content of 1% or less. The thermal conductivity, K, of coarse, dry sand varies between 0.15 – 0.25 W/mK. Converting to Imperial units = 1.7 Btu.in/ft2.oF.hr. R-value is the reciprocal of conductivity, therefore, the R-value of coarse dry sand = 0.58 ft2.oF.hr/Btu.in.

1-inch of fiberglass insulation with a conductivity of 0.27 has an R-value of 3.70. Conversely, 6″ of dry coarse sand has an R-value of 3.46; 12″ would have an R-value of 6.92.

In addition, some provisions need to be made to keep the insulating sand as dry as possible.