Frost line depth in Henry County, VA
How deep the ground freezes in Henry County, VA
14 in. Dig to 15 in, just below the frost. Nearest NOAA station: Martinsville Fltr Plt, 8.6 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.