Frost line depth in LaSalle County, IL

How deep the ground freezes in LaSalle County, IL

33 in. Dig to 34 in, just below the frost. Nearest NOAA station: Ottawa 5sw, 1.6 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.

Code depth · Snow