Frost line depth in Iredell County, NC
How deep the ground freezes in Iredell County, NC
13 in. Dig to 13 in, just below the frost. Nearest NOAA station: Statesville 2 Nne, 0.4 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.