Frost Depth Footer Calculator

Determine minimum footing depth based on frost line depth for your region. Prevents frost heave damage to foundations, piers, and walls.

Results

Visualization

How It Works

Frost heave occurs when water in soil freezes and expands, pushing foundations upward. Footings must extend below the frost line to prevent heave. Frost depths range from 6 inches in the South to 60+ inches in Alaska. The IRC requires footers at least 12 inches below finished grade and below the frost line. Heated buildings reduce frost depth adjacent to the foundation by about 15%. Frost-protected shallow foundations (FPSF) use rigid foam insulation to reduce required depth.