Frost line depth in Johnston County, NC

How deep the ground freezes in Johnston County, NC

9 in. Dig to 12 in, the 12 in code minimum. Nearest NOAA station: Smithfield, 1.3 mi.

Your building department sets the legal frost line depth (IRC Table R301.2(1)); footings must go below it (R403.1.4.1). Call them before you dig.

12 in minimum · Snow