Frost line depth in Buchanan County, MO
How deep the ground freezes in Buchanan County, MO
25 in. Dig to 26 in, just below the frost. Nearest NOAA station: St Joseph Rosecrans Ap, 9.9 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.