The Cold 80+ Freeze-Thaw Cycles Heave Shallow Posts Out of the Ground
When water in the soil around a fence post freezes, it expands by about 9% — and it pushes everything buried in the ground upward. In Kansas City, this freeze-and-thaw cycle happens more than 80 times every winter. Posts set at 18–24 inches rise 2 to 3 inches in a single season, dragging the entire fence out of plumb with them.
- Freezing water expands 9%. That force pushes anything buried upward.
- Kansas City's frost line is 30–36 inches deep. Only posts below that line stay put.
- A common shortcut is to set posts at 18–24 inches. That's exactly where freeze-thaw is strongest.