Frost line depth in Jefferson County, IL

How deep the ground freezes in Jefferson County, IL

21 in. Dig to 21 in, just below the frost. Nearest NOAA station: Mt Vernon 3 Ne, 5.1 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.

Code depth · Snow