Types of foundations

Strip foundation

Often termed a continuous footing this foundation has a length significantly greater than its width. It is generally used to support a series of columns or a wall.

Pad footing

Generally an individual foundation designed to carry a single column load although there are occasions when a pad foundation supports two or more columns.

Raft foundation

This is a generic term for all types of foundations that cover large areas. A raft foundation is also called a mat foundation and can vary from a fascine mattress supporting a farm road to a large reinforced concrete basement supporting a high rise block.

Pile foundation

Piles are used to transfer structural loads to either the foundation soil or the bedrock underlying the site. They are usually designed to work in groups with the column loads they support transferred into them via a capping slab.

Pier foundation

This is a large column built up from either the bedrock or from a slab supported by piles. Its purpose is to support a large load, such as that from a bridge. A pier operates in the same manner as a pile but it is essentially a short squat column whereas a pile is relatively longer and more slender.

Shallow foundation

A foundation whose depth below the surface, z, is equal to or is less than its least dimension, B. Most strip and pad footings fall into this category.

Deep foundation

A foundation whose depth below the surface is greater than its least dimension. Piles and piers fall into this category.

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