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Home Glossary Foundation
Foundations noun

Foundation

/fown-DAY-shun/

Also known as: footings, foundations, substructure

The structural element at the base of a building that transfers loads from the superstructure safely into the ground. Foundations must be designed to suit the ground conditions, load, and proximity to trees or drainage. The main types are strip, raft, pad, and pile foundations.

Foundation type and depth are determined by a ground investigation and structural engineer. In the UK, strip foundations for domestic construction are typically 1m deep in shrinkable clay (deeper near trees) and 600mm minimum in stable ground. Building Control will inspect foundations before concrete is poured.

Approved Document A - Structure

Min. depth in stable ground600mm
Min. depth in shrinkable clay900mm-1m+
Near trees (clay)Consult engineer
StandardBS 8004 (Foundations)

Foundation depth near trees on shrinkable clay soils must account for root influence zones - often requiring 1.5m-3m depth or a piled solution. Always consult a structural engineer.