GA · statewide code figure
How deep do deck footings and fence posts have to go in Georgia? Below the frost line. Here's the number, and the winter behind it.
The requirement
12″
Footing bottoms in Georgia must reach 12 inches below grade — the frost line. Uniform across the state.
Reference: Georgia State Minimum Standard One- and Two-Family Dwelling Code (2024 IRC with Georgia Amendments), Section R403.1.4 (2024 edition). Counties amend their codes — confirm the exact figure with your local building department before you pour.
Depth pre-filled to the Georgia frost line. The hole bottom has to reach it — a few inches deeper seats the base cleanly below.
| Bag size | Exact | Buy (with spare) |
|---|
The buy column adds a 10% spare margin and rounds up. Running out mid-pour is the one mistake you can't fix.
Georgia winters are short and mild, so frost seldom penetrates more than a few inches — roughly 6 to 10 inches in the Blue Ridge mountains and essentially zero on the coast. The 12-inch stability minimum is deeper than the frost line nearly everywhere in the state.
The depth tracks how much freezing a winter actually delivers. NOAA's Air Freezing Index keeps a running score of how far and how long air temperatures sit below freezing; deeper scores mean deeper frost, and building codes translate that climate record into the footing depth above. Water expands about 9% when it freezes — when that happens under a footing, the ground lifts it. That's frost heave, and it cracks foundations, tilts fence lines, and pops deck piers. Getting below the frost line puts your concrete where the ground never freezes.
Georgia's mandatory statewide code sets the 12-inch minimum, while frost line entries in Table R301.2(1) are filled in by each local jurisdiction; a few north Georgia mountain counties may ask for slightly deeper footings. Even in frost-free south Georgia the 12-inch minimum below grade still applies.
Treat this page as the starting number, not the permit. County and city amendments are where the real precision lives, and inspectors enforce the local figure — one phone call to the building department settles it.
12 inches is the working number (statewide code figure). Uniform across the state. Confirm the exact figure with your local building department — county amendments are common.
Bury one third of the above-grade height, never less than 24″, and never shallower than the frost line — in Georgia that means at least 24″. The post depth calculator checks both rules for you.
Below the frost line — 12″ minimum, bearing on undisturbed soil beneath it. Size the diameter with the deck footing calculator, then figure bags with the depth pre-filled above.
Yes — 811 covers every state, and the locate is free. Call a few business days before any post hole or footing dig and crews mark the buried utilities.