Foundation / Foundation strengthening
Underpinning
/ˈʌn.dərˌpɪn.ɪŋ/noun
From under and pin, in the old sense of supporting or propping up.
Definition
The process of strengthening or deepening the foundation of an existing building, usually by extending support down to firmer ground.
Fig. 63 — Underpinning: schematic studyNOT TO SCALE
Illustrative study — Underpinning · AI-generatedSAMPLE IMAGE
Photo study — Underpinning · AI-generated00:06
Structural & construction notes
Traditional mass-concrete underpinning is dug in short alternating bays so the wall is never left unsupported. Mini-piles, jet grouting, and needle beams are alternatives. Work needs temporary support and monitoring for movement.
An educational reference. Project-specific design requires professional guidance.