Frost Line Depth Calculator
Estimate the frost penetration depth in soil based on the freezing index degree-days.
Estimated Frost Depth32 inches
Why Frost Depth Matters
When soil freezes, the water inside it expands, causing "frost heave." If building foundations, deck footings, or water pipes are placed above the frost line, this heaving will push them upward and cause catastrophic structural damage.
Calculating Depth
Frost depth can be estimated empirically using the Air Freezing Index, which tracks the cumulative number of degree-days below freezing in a given region during winter.
Frequently Asked Questions
Does soil type affect the frost line?
Yes. Sandy, well-draining soils freeze deeper than dense clays, but they heave less because they hold less water. This calculator provides a generalized approximation; always consult local building codes for exact footing depth requirements.