Frost line depth in Ada County, ID

How deep the ground freezes in Ada County, ID

17 in. Dig to 18 in, just below the frost. Nearest NOAA station: Boise Air Terminal, 8 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