Ohio's residential code sets a 12 inch floor for exterior footings and then sends builders deeper to whatever frost line depth the local building department has filled into Table 301.2(1), so the number a reader needs comes from the county or city building department rather than from the state.
Ohio leaves the frost line depth to the local building department, which is where the number for an address comes from.
The jurisdiction shall fill in the frost line depth column with the minimum depth of footing below finish grade.Ohio Administrative Code rule 4101:8-3-01, Building planning, Table 301.2(1), Ohio Board of Building Standards, read September 22, 2026. Read it at the source
That makes the building department issuing the permit the office with the number, and it is a short call: the counter gives the depth for the address, and the same call settles whether a deck footing or a slab edge needs a footing inspection before the concrete goes in. What Ohio does publish is below, and it is worth having in hand first.
A frost line depth turns into two separate requirements in most codes: how far a footing has to bear below grade, and how far a buried water service has to sit below the same line. Ohio writes one of them out.
Exterior footings go at least 12 inches below undisturbed ground, and deeper where the local jurisdiction's frost line depth requires it; a footing may instead be a frost protected shallow foundation, built to ASCE 32, or set on solid rock.
403.1.4 Minimum depth. Exterior footings shall be placed not less than 12 inches (305 mm) below the undisturbed ground surface. Where applicable, the depth of footings shall also conform to Sections 403.1.4.1.Ohio Administrative Code rule 4101:8-4-01, Foundations, sections 403.1.4 and 403.1.4.1, Ohio Board of Building Standards, read September 22, 2026. Read it at the source
The air freezing index is the quantity the frost provisions of the model codes are written on: add up how far each day’s mean temperature fell below freezing over a winter, in degree days, and take the deepest run the winter managed. It measures how much cold the ground had to absorb, which is why it is the honest way to set one place beside another. Youngstown is the coldest of the 3 cities on the record in Ohio.
518degree days
average freezing index a winter
Youngstown-Warren Rgnl AP
| City | State | Freezing index | Once a century | Nights below freezing |
|---|---|---|---|---|
| Youngstown | Ohio | 518 | 1,367 | 130 |
| Cleveland | Ohio | 428 | 1,219 | 116 |
| Columbus | Ohio | 337 | 1,031 | 111 |
Computed from NOAA National Centers for Environmental Information, Global Historical Climatology Network daily temperature records for each station, from 1951 onward. These are measurements of winter, not depths.
Only a handful of states answer with one number for the whole state, and they are the only codes that can be set beside each other directly. Ranked by the freezing index at their own reference cities, with Ohio marked at 428 degree days for comparison against what those codes settled on:
Left to right, the mildest winters to the hardest. The figure on the right is what that state wrote into its code.
The nearest by winter are Massachusetts at 4 feet, Connecticut at 42 inches and North Carolina at 12 inches. That is a reading of other states’ codes rather than a depth for an address in Ohio: soil, drainage, snow cover and local amendments all move the figure, and the building department issuing the permit is the office whose number binds.
Ohio code read September 22, 2026 from Ohio Administrative Code rule 4101:8-3-01, Building planning, Table 301.2(1), Ohio Board of Building Standards. Codes are amended and a local amendment can be deeper than the state figure, so the building department issuing the permit has the number that binds. Every state is on the frost line depth hub.