Insights Library
Who Pays When a Neighbour’s Excavation Causes Your Land to Subside?
Retaining-wall disputes are not always about where the wall sits or whether neighbours should split the cost. The real question is often what caused the difference in land levels and who is responsible for providing support?
At common law, land has a natural right to lateral support from adjoining land.
A property owner may excavate their land, but not in a way that removes the natural support of neighbouring land and causes it to subside, slip or erode. Liability may arise in private nuisance even if there is no agreement requiring a retaining wall. The right principally protects the land in its natural condition.
A fence marks or encloses a boundary. A retaining wall holds back soil.
If excavation on one property created the need for support, the issue may not be an ordinary boundary-cost dispute. The responsibility for the wall will depend on the cause of the instability, rather than simply its proposed location.
Best Hooper recently advised on a matter involving higher residential land adjoining an old quarry. Earlier expert evidence recorded an extensive quarry cut along the boundary, a steep embankment and a substantial level drop. The owner of the higher land reported that erosion had continued and soil was being lost towards the quarry cut. Although the quarrying predated the current owners, that did not require the higher owner to pay for support made necessary by excavation on the adjoining land and these costs were substantial.
Note, there is no automatic rule that retaining-wall costs must be shared equally. Responsibility may depend on the properties’ natural levels, which land was excavated or filled, what caused the soil movement, whether buildings, drainage or landscaping contributed, the purpose of the proposed wall and the engineering work reasonably required.
So evidence matters. Before responsibility is accepted or a formal demand is made, the affected owner should obtain appropriate geotechnical engineering evidence, historical photographs, surveys, planning records and expert reports. We gather it and it informs the outcome.
How Best Hooper can help
We advise property owners in all property disputes including obscure ones, just like this one involving retaining walls and excavation, loss of lateral support. We also advise in boundary and fencing issues, land instability and drainage, easements and access, expert engineering evidence and negotiations and court proceedings.
If your land is subsiding near a boundary, or you have been asked to contribute to a retaining wall, obtain legal advice from us before accepting responsibility for the works.
