Frost Line

Definition

The frost line is the depth in the earth to which the soil is expected to freeze during winter, which has the potential to damage construction elements such as footings and pipes.

Purpose

The purpose of understanding the frost line is to ensure that foundations, footings, and other construction elements are placed below this depth to prevent damage from soil freezing and thawing cycles.

Examples of Use

• In residential construction, footings and foundations are typically placed below the frost line to prevent frost heave and structural damage.
• Utility companies install water and sewer pipes below the frost line to avoid freezing and bursting in cold weather.

Related Terms

• Frost Heave: The upward movement of soil during freezing conditions, which can damage foundations and other structures.
• Permafrost: Permanently frozen ground found in polar regions.
• Subgrade: The soil prepared to support a structure or pavement system.

Notes

The depth of the frost line varies by geographic location and climate. Local building codes often specify the required depth for foundations and footings to prevent frost-related damage.