Underpinning refers to the process or art of repairing the existing foundation of a building or structure
Underpinning is commonly referred to as foundation repair and there are several types. In order to choose
the proper underpinning method, examine and understand the architecture of the existing structure, the foundation
supports and the exact problem with the foundation.
The function of underpinning, or repairing a foundation, is necessary in situations in which the existing
foundation is unable to support the weight of the structure or is not stable enough. Also, when nearby construction
and excavation has affected the soil support system of the existing foundation, underpinning is also necessary.
Additional causes for underpinning include changes in the function of the structure and weight supported by the
Several underpinning methods repair and provide support for an existing foundation. The types include
various systems of piers and piles, such as bracket piles, helical piers, screw piles, hand-dug piers, jacked piles
and mini-piles. The types of piers and piles differ according to the installation process, other materials used for
underpinning and the layout of the piers or piles.
Before underpinning, foundation structural engineers must prepare the proper calculation for bracing a
temporary support system and drawings so the Contractor can work safely underneath the existing structure and
foundation. The proper contractor must make temporary support with steel beams inserted at angles underneath
the edges of the foundation. Once the support system is in place, contractor dig holes under the structure, and
construct the new support system or foundation. When the underpinning is complete, the final step involves
removing the temporary support system.
During the underpinning process, the piles and piers are built to extend to stable soil, or soil resistant to compacting
and settling, so the repaired foundation nor the structure it supports should not move.
Underpinning is expensive, regardless of the type, work price depending upon conditions and or state of the type
|Pictures and Drawings use on St.Clair Ave. E
|Columns and Footing Pictures St.Clair Ave. E
|Don Mills and Laurence Outside Underpinning
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John-Luc Rizzo General Contractor