Frost Line Depth in the UK

In the UK, the frost line (depth where soil doesn't freeze) typically ranges from 40 to 90 cm (16–36 inches), varying by:

• Location: deeper in milder south/east; shallower in colder north/west.
• Soil: deeper in well-drained; shallower in poorly-drained soils.

Construction Importance

Foundations must extend below the frost line to prevent frost heave (freezing water expands, lifting structures). UK building regulations set minimum foundation depths based on local conditions (e.g., 45 cm in favorable areas, 90 cm in severe).

Gardening Impact

Planting depth must protect roots from freezing; deeper frost line requires deeper planting.