Frost line depth in Franklin County, AL
How deep the ground freezes in Franklin County, AL
12 in. Dig to 12 in, the 12 in code minimum. Nearest NOAA station: Russellville 4 Sse, 7.6 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.