WDO Home Inspection Practice Exam 2025 – Comprehensive Prep Guide

The term that describes the depth of frost penetration in the local soil is the frost line. This term is essential for understanding how freezing temperatures affect the ground and subsequently inform various construction practices, including foundation depth. The frost line indicates the deepest point at which soil temperatures drop to 32°F (0°C) or lower.

In construction and engineering, knowing the frost line helps determine how deep footings should be placed to prevent frost heave, which can cause structural damage as the ground expands and contracts with freezing and thawing cycles.

The other terms may refer to related concepts but do not accurately define the specific depth of frost penetration. For instance, while "ice line" may suggest the layering of ice, it does not imply a specific depth in soil. "Freeze cutoff" might imply a method or point of frost limitation but lacks a direct correlation to soil penetration depth. "Hard ground" generally refers to compacted soil conditions, not specifically related to frost penetration. Thus, the frost line is the most precise term for describing the depth of frost penetration in soil.