United Kingdom · answered by Verika · verified against sources
How deep do strip foundations need to be?
Strip foundations must be at least 0.45m deep to avoid frost action, but this may increase in areas with prolonged frost or to reach satisfactory ground. For shrinkable clays (Modified Plasticity Index ≥10%), depths vary: 0.75m (low shrinkage), 0.9m (medium), or 1.0m (high), with adjustments for trees or loading [1].
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