Ohio Frost Line Depth Is Set by Your City, Not the State

If you are looking for an Ohio frost depth, there isn't one, and that is a deliberate feature of how the state's code is written rather than a gap. 2(1) is left empty, with a footnote instructing that the jurisdiction shall fill in the frost line depth column with the minimum depth of footing below finish grade. So the number that governs your footings is set by your city, village, township or county building department, not by Columbus. The same footnote adds a rule worth knowing: where the frost line depth requires deeper footings than the model figure indicates, the depth required for weathering governs.

Ohio classifies weathering as severe everywhere in the state, so that condition is not hypothetical. Practically, this means two things, find your local jurisdiction's adopted figure, and expect it to be a floor rather than a ceiling.

Because the depth is local, enforcement is local: the figure is checked at the foundation inspection by whichever jurisdiction issued your permit. The trap specific to Ohio is assuming a neighbouring city's number carries over. It does not, and there is no statewide default to fall back on if your jurisdiction's figure is hard to find.