Frost line depth in Grafton County, NH

How deep the ground freezes in Grafton County, NH

40 in. Dig to 40 in, just below the frost. Nearest NOAA station: Wentworth, 5.5 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