Underpinning

Underpinning is a process used to repair, strengthen, or increase the depth of an existing foundation by lowering the footing to allow it to rest on more supportive soil.

While oftentimes underpinning is associated with the remediation of deficient or failing foundations, it is also used in cases where the use of a building has changed, floors are being added to upper stories, or additional depth is desired in subsurface spaces, such as basements or cellars.

In dense urban locations, such as New York City, underpinning is also a common practice during the construction of adjoining, adjacent, or nearby structures that require the removal or excavation of the soil supporting the neighboring properties.

The process of underpinning begins by removing or excavating the soil from beneath an existing foundation.