AskDefine | Define underpinning

Dictionary Definition

underpinning (See underpin)

Verb

1 support from beneath
2 support with evidence or authority or make more certain or confirm; "The stories and claims were born out by the evidence" [syn: corroborate, bear out, support] [also: underpinning, underpinned]

User Contributed Dictionary

English

Verb

underpinning
  1. present participle of underpin

Noun

  1. A support or foundation, especially a structure of masonry that supports a wall etc

Extensive Definition

In construction, underpinning is the process of strengthening and stabilizing the foundation of an existing building or other structure. Underpinning may be necessary for a variety of reasons:
  • The original foundation is simply not strong or stable enough, e.g. due to decay of wooden piles under the foundation.
  • The usage of the structure has changed.
  • The properties of the soil supporting the foundation may have changed (possibly through subsidence) or were mischaracterized during planning.
  • The construction of nearby structures necessitates the excavation of soil supporting existing foundations.
  • It is more economical, due to land price or otherwise, to work on the present structure's foundation than to build a new one.
Underpinning is accomplished by extending the foundation in depth or in breadth so it either rests on a stronger soil stratum or distributes its load across a greater area. Use of micropiles http://www.ismicropiles.org and jet grouting are common methods in underpinning. An alternative to underpinning is the strengthening of the soil by the introduction of a grout. All of these processes are generally expensive and elaborate.
Underpinning may be necessary where P class (problem) soils in certain areas of the site are encountered,

Synonyms, Antonyms and Related Words

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