Underpinning strengthens and deepens existing foundations where they are inadequate or affected by subsidence or movement. The most common method excavates in sequence beneath the existing footing and fills with mass concrete to transfer load onto firmer ground. Also used to enable side-return extensions along the party wall line.
[link_suggest: Extensions (#995), Brickwork Repairs & Repointing (#1024), Damp Proofing (#1021)]