Piles undermined

Causes

Unconsented excavation to create a basement space

Slumping of existing excavation

Common

Listed under: Subfloor, basements, piles

Cause

Unconsented excavation to create a basement space

Repair

  • excavation can seriously weaken foundations, especially where:
    • it is extensive and has undermined foundations
    • it has left piles close to the edge of an unsupported bank
    • the pile footings have been exposed
  • a chartered professional engineer or registered building surveyor should be called in to give an opinion
  • shovelling soil back around the footings or base of the piles is not a solution. It will not provide the strength needed in the foundations
  • in some cases, repiling or the installation of new members to support the floor may be required. This falls into the category of ‘restricted building work’. When done by a contractor, it must be carried out or supervised by a licensed building practitioner with a Foundations licence
  • if the excavation affects one or two piles, replacing these in the same location will not require a building consent (but still needs to comply with the Building Act). Repiling all of a house or a substantial area will require building consent.

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Cause

Slumping of existing excavation

Repair

  • as for the repair above

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